Author name code: mason
ADS astronomy entries on 2022-09-14
author:"Mason, Helen E." 
------------------------------------------------------------------------  

Title: Multiwavelength Observations by XSM, Hinode, and SDO of an
    Active Region. Chemical Abundances and Temperatures
Authors: Del Zanna, G.; Mondal, B.; Rao, Y. K.; Mithun, N. P. S.;
   Vadawale, S. V.; Reeves, K. K.; Mason, H. E.; Sarkar, A.; Janardhan,
   P.; Bhardwaj, A.
Bibcode: 2022ApJ...934..159D
Altcode: 2022ApJ...934..159Z; 2022arXiv220706879D
  We have reviewed the first year of observations of the Solar X-ray
  Monitor (XSM) on board Chandrayaan-2 and the available multiwavelength
  observations to complement the XSM data, focusing on the Solar
  Dynamics Observatory AIA and Hinode XRT and EIS observations. XSM has
  provided disk-integrated solar spectra in the 1-15 keV energy range,
  observing a large number of microflares. We present an analysis of
  multiwavelength observations of AR 12759 during its disk crossing. We
  use a new radiometric calibration of EIS to find that the quiescent
  active region (AR) core emission during its disk crossing has a
  distribution of temperatures and chemical abundances that does
  not change significantly over time. An analysis of the XSM spectra
  confirms the EIS results and shows that the low first ionization
  potential (FIP) elements are enhanced compared to their photospheric
  values. The frequent microflares produced by the AR did not affect the
  abundances of the quiescent AR core. We also present an analysis of
  one of the flares it produced, SOL2020-04-09T09:32. The XSM analysis
  indicates isothermal temperatures reaching 6 MK. The lack of very
  high-T emission is confirmed by AIA. We find excellent agreement
  between the observed XSM spectrum and the one predicted using an AIA
  DEM analysis. In contrast, the XRT Al-poly/Be-thin filter ratio gives
  lower temperatures for the quiescent and flaring phases. We show that
  this is due to the sensitivity of this ratio to low temperatures,
  as the XRT filter ratios predicted with a DEM analysis based on EIS
  and AIA give values in good agreement with the observed ones.

Title: Diagnostics of non-Maxwellian electron distributions in solar
    active regions from Fe XII lines observed by Hinode/EIS and IRIS
Authors: Del Zanna, G.; Polito, V.; Dudík, J.; Testa, P.; Mason,
   H. E.; Dzifčáková, E.
Bibcode: 2022arXiv220707026D
Altcode:
  We present joint Hinode/EIS and IRIS observations of Fe XII lines
  in active regions, both on-disk and off-limb. We use an improved
  calibration for the EIS data, and find that the 192.4 A / 1349 A
  observed ratio is consistent with the values predicted by CHIANTI and
  the coronal approximation in quiescent areas, but not in all active
  region observations, where the ratio is often lower than expected
  by up to a factor of about two. We investigate a number of physical
  mechanisms that could affect this ratio, such as opacity and absorption
  from cooler material. We find significant opacity in the EIS Fe XII
  193 and 195 A lines, but not in the 192.4 A line, in agreement with
  previous findings. As we cannot rule out possible EUV absorption by
  H, He and He II in the on-disk observations, we focus on an off-limb
  observation where such absorption is minimal. After considering these,
  as well as possible non-equilibrium effects, we suggest that the most
  likely explanation for the observed low Fe XII 192.4 A / 1349 A ratio
  is the presence of non-Maxwellian electron distributions in the active
  regions. This is in agreement with previous findings based on EIS and
  IRIS observations independently.

Title: Diagnostics of Non-Maxwellian Electron Distributions in
    Solar Active Regions from Fe XII Lines Observed by the Hinode
    Extreme Ultraviolet Imaging Spectrometer and Interface Region
    Imaging Spectrograph
Authors: Del Zanna, G.; Polito, V.; Dudík, J.; Testa, P.; Mason,
   H. E.; Dzifčáková, E.
Bibcode: 2022ApJ...930...61D
Altcode:
  We present joint Hinode Extreme Ultraviolet Imaging Spectrometer
  (EIS) and Interface Region Imaging Spectrograph (IRIS) observations
  of Fe XII lines in active regions, both on-disk and off-limb. We use
  an improved calibration for the EIS data, and find that the 192.4
  Å/1349 Å observed ratio is consistent with the values predicted by
  CHIANTI and the coronal approximation in quiescent areas, but not in
  all active-region observations, where the ratio is often lower than
  expected by up to a factor of about two. We investigate a number of
  physical mechanisms that could affect this ratio, such as opacity and
  absorption from cooler material. We find significant opacity in the EIS
  Fe XII 193 and 195 Å lines, but not in the 192.4 Å line, in agreement
  with previous findings. As we cannot rule out possible EUV absorption by
  H, He, and He II in the on-disk observations, we focus on an off-limb
  observation where such absorption is minimal. After considering these,
  as well as possible nonequilibrium effects, we suggest that the most
  likely explanation for the observed low Fe XII 192.4 Å/1349 Å ratio
  is the presence of non-Maxwellian electron distributions in the active
  regions. This is in agreement with previous findings based on EIS and
  IRIS observations independently.

Title: The centre-to-limb variation of non-thermal velocities using
    IRIS Si IV
Authors: Rao, Yamini K.; Del Zanna, Giulio; Mason, Helen E.
Bibcode: 2022MNRAS.511.1383R
Altcode: 2022arXiv220107290R; 2022MNRAS.tmp..149R
  We study the non-thermal velocities in the quiet Sun using various
  high spatial, temporal, and spectral resolution observations from the
  Interface Region Imaging Spectrograph (IRIS). We focus our analysis on
  the transition region using the optically thin line (Si IV 1393.7 Å),
  and select line profiles that are nearly Gaussian. We find evidence
  of a centre-to-limb variation using different observations having
  different exposure times, ranging from 5 to 30 s. The distribution of
  non-thermal velocities close to the limb is observed to peak around
  20 km s<SUP>-1</SUP> while the disc observations show a peak around
  15 km s<SUP>-1</SUP>. The distributions are also different. The
  overall variation in the non-thermal velocities are correlated with
  the intensity of the line, as found previously. The on-disc velocities
  are smaller than most previous observations. In general, we find that
  the non-thermal velocities are independent of the selected exposure
  times. The Si IV lines did not seem to exhibit any significant opacity
  effects. We conclude that these Doppler motions are mostly transverse
  to the radial direction. The possibility of swaying/torsional motions
  leading to such variations are validated from these IRIS observations.

Title: Preliminary Results from the Marshall Grazing Incidence X-ray
    Spectrometer (MaGIXS)
Authors: Winebarger, Amy; Savage, Sabrina; Kobayashi, Ken; Champey,
   Patrick; Golub, Leon; Walsh, Robert; Athiray, P. S.; Bradshaw, Stephen;
   Cheimets, Peter; Cirtain, Jonathan; DeLuca, Edward; Del Zanna, Giulio;
   Mason, Helen; McKenzie, David; Ramsey, Brian; Reeves, Katharine;
   Testa, Paola; Vigil, Genevieve; Warren, Harry
Bibcode: 2021AGUFMSH51A..06W
Altcode:
  Coronal heating mechanisms are notoriously difficult to constrain with
  current observations. We present new observations from an instrument
  designed to measure a critical diagnostic of the frequency heating
  events in active regions. The Marshall Grazing Incidence X-ray
  Spectrometer (MaGIXS) is a sounding rocket mission that aims to
  observe the soft x-ray solar spectrum (0.6 2.5 nm) with both spatial
  and spectral resolution. This wavelength range has several high
  temperature and abundance diagnostics that can be used to infer the
  coronal heating frequency. MaGIXS will observe the Sun through a 12
  x 33 slot, producing ``overlappograms, where the spatial and spectral
  information are overlapped and must be unfolded. In this presentation,
  I will report on the MaGIXS launch and data collection and provide
  preliminary analysis of MaGIXS observations.

Title: Evolution of Elemental Abundances during B-Class Solar Flares:
    Soft X-Ray Spectral Measurements with Chandrayaan-2 XSM
Authors: Mondal, Biswajit; Sarkar, Aveek; Vadawale, Santosh V.;
   Mithun, N. P. S.; Janardhan, P.; Del Zanna, Giulio; Mason, Helen E.;
   Mitra-Kraev, Urmila; Narendranath, S.
Bibcode: 2021ApJ...920....4M
Altcode: 2021arXiv210707825M
  The Solar X-ray Monitor (XSM) payload on board Chandrayaan-2 provides
  disk-integrated solar spectra in the 1-15 keV energy range with an
  energy resolution of 180 eV (at 5.9 keV) and a cadence of 1 s. During
  the period from 2019 September to 2020 May, covering the minimum of
  Solar Cycle 24, it observed nine B-class flares ranging from B1.3 to
  B4.5. Using time-resolved spectroscopic analysis during these flares,
  we examined the evolution of temperature, emission measure, and absolute
  elemental abundances of four elements-Mg, Al, Si, and S. These are
  the first measurements of absolute abundances during such small flares
  and this study offers a unique insight into the evolution of absolute
  abundances as the flares evolve. Our results demonstrate that the
  abundances of these four elements decrease toward their photospheric
  values during the peak phase of the flares. During the decay phase,
  the abundances are observed to quickly return to their preflare coronal
  values. The depletion of elemental abundances during the flares is
  consistent with the standard flare model, suggesting the injection
  of fresh material into coronal loops as a result of chromospheric
  evaporation. To explain the quick recovery of the so-called coronal
  "First Ionization Potential bias" we propose two scenarios based on
  the Ponderomotive force model.

Title: Thermodynamic evolution of a sigmoidal active region with
    associated flares
Authors: Mulay, Sargam M.; Tripathi, Durgesh; Mason, Helen
Bibcode: 2021MNRAS.504.1201M
Altcode: 2021MNRAS.tmp..832M; 2021arXiv210309561M
  Active regions often show S-shaped structures in the corona called
  sigmoids. These are highly sheared and twisted loops formed along
  the polarity inversion line. They are considered to be one of the best
  pre-eruption signatures for CMEs. Here, we investigate the thermodynamic
  evolution of an on-disc sigmoid observed during 2015 December 24-28. For
  this purpose, we have employed Emission Measure (EM) and filter-ratio
  techniques on the observations recorded by the Atmospheric Imaging
  Assembly (AIA) on-board the Solar Dynamics Observatory (SDO) and X-ray
  Telescope (XRT) on-board Hinode. The EM analysis showed multithermal
  plasma along the sigmoid and provided a peak temperature of ~10-12.5
  MK for all observed flares. The sigmoidal structure showed emission
  from Fe XVIII (93.93 Å) and Fe XXI (128.75 Å) lines in the AIA 94 and
  131 Å channels, respectively. Our results show that the hot plasma is
  often confined to very hot strands. The temperature obtained from the
  EM analysis was found to be in good agreement with that obtained using
  the XRT, AIA, and GOES filter-ratio methods. These results provide
  important constraints for the thermodynamic modelling of sigmoidal
  structures in the core of active regions. Moreover, this study also
  benchmarks different techniques available for temperature estimation
  in solar coronal structures.

Title: High resolution soft X-ray spectroscopy and the quest for
    the hot (5-10 MK) plasma in solar active regions
Authors: Del Zanna, Giulio; Andretta, Vincenzo; Cargill, Peter J.;
   Corso, Alain J.; Daw, Adrian N.; Golub, Leon; Klimchuk, James A.;
   Mason, Helen E.
Bibcode: 2021FrASS...8...33D
Altcode: 2021arXiv210306156D
  We discuss the diagnostics available to study the 5--10 MK plasma in
  the solar corona, which is key to understanding the heating in the
  cores of solar active regions. We present several simulated spectra,
  and show that excellent diagnostics are available in the soft X-rays,
  around 100 Angstroms, as six ionisation stages of Fe can simultaneously
  be observed, and electron densities derived, within a narrow spectral
  region. As this spectral range is almost unexplored, we present an
  analysis of available and simulated spectra, to compare the hot emission
  with the cooler component. We adopt recently designed multilayers to
  present estimates of count rates in the hot lines, with a baseline
  spectrometer design. Excellent count rates are found, opening up
  the exciting opportunity to obtain high-resolution spectroscopy of
  hot plasma.

Title: 'We love STEAM!'
Authors: Mason, Helen; Schell, Helen
Bibcode: 2021A&G....62.1.26M
Altcode:
  Helen Mason and Helen Schell explain how the SunSpaceArt outreach
  programme flourished in 2020, bringing art and science together for
  pupils and teachers

Title: Electron Densities in the Solar Corona Measured Simultaneously
    in the Extreme Ultraviolet and Infrared
Authors: Dudík, Jaroslav; Del Zanna, Giulio; Rybák, Ján;
   Lörinčík, Juraj; Dzifčáková, Elena; Mason, Helen E.; Tomczyk,
   Steven; Galloy, Michael
Bibcode: 2021ApJ...906..118D
Altcode: 2020arXiv201109175D
  Accurate measurements of electron density are critical for
  determination of the plasma properties in the solar corona. We compare
  the electron densities diagnosed from Fe XIII lines observed by the
  Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode
  mission with the near-infrared (NIR) measurements provided by the
  ground-based Coronal Multichannel Polarimeter (CoMP). To do that, the
  emissivity-ratio method based on all available observed lines of Fe
  XIII is used for both EIS and CoMP. The EIS diagnostics is further
  supplemented by the results from Fe XII lines. We find excellent
  agreement, within 10%, between the electron densities measured from both
  extreme-ultraviolet and NIR lines. In the five regions selected for
  detailed analysis, we obtain electron densities of log(N<SUB>e</SUB>
  [cm<SUP>-3</SUP>]) = 8.2-8.6. Where available, the background
  subtraction has a significant impact on the diagnostics, especially on
  the NIR lines, where the loop contributes less than a quarter of the
  intensity measured along the line of sight. For the NIR lines, we find
  that the line center intensities are not affected by stray light within
  the instrument, and recommend using these for density diagnostics. The
  measurements of the Fe XIII NIR lines represent a viable method for
  density diagnostics using ground-based instrumentation.

Title: Study of the spatial association between an active region
    jet and a nonthermal type~${\rm III}$ radio burst
Authors: Mulay, Sargam M.; Sharma, Rohit; Valori, Gherardo; Vásquez,
   Alberto M.; Del Zanna, Giulio; Mason, Helen; Oberoi, Divya
Bibcode: 2020arXiv200914581M
Altcode:
  We aim to investigate the spatial location of the source of an active
  region (AR) jet and its relation with associated nonthermal type~III
  radio emission. An emission measure (EM) method was used to study
  the thermodynamic nature of the AR jet. The nonthermal type~{\rm III}
  radio burst observed at meterwavelength was studied using the Murchison
  Widefield Array (MWA) radio imaging and spectroscopic data. The local
  configuration of the magnetic field and the connectivity of the source
  region of the jet with open magnetic field structures was studied using
  a nonlinear force-free field (NLFFF) extrapolation and potential field
  source surface (PFSS) extrapolation respectively. The plane-of-sky
  velocity of the AR jet was found to be $\sim$136~km/s. The EM analysis
  confirmed the presence of low temperature 2~MK plasma for the spire,
  whereas hot plasma, between 5-8 MK, was present at the footpoint region
  which also showed the presence of Fe~{\sc xviii} emission. A lower limit
  on the electron number density was found to be 1.4$\times$10$^{8}$
  cm$^{-3}$ for the spire and 2.2$\times$10$^{8}$~cm$^{-3}$ for
  the footpoint. A temporal and spatial correlation between the AR
  jet and nonthermal type III burst confirmed the presence of open
  magnetic fields. An NLFFF extrapolation showed that the photospheric
  footpoints of the null point were anchored at the location of the
  source brightening of the jet. The spatial location of the radio
  sources suggests an association with the extrapolated closed and
  open magnetic fields although strong propagation effects are also
  present. The multi-scale analysis of the field at local, AR, and solar
  scales confirms the interlink between different flux bundles involved
  in the generation of the type III radio signal with flux transferred
  from a small coronal hole to the periphery of the sunspot via null
  point reconnection with an emerging structure.

Title: Plasma Diagnostics from Active Region and Quiet-Sun Spectra
Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian
    Distribution
Authors: Lörinčík, Juraj; Dudík, Jaroslav; del Zanna, Giulio;
   Dzifčáková, Elena; Mason, Helen E.
Bibcode: 2020ApJ...893...34L
Altcode: 2020arXiv200307091L
  We perform plasma diagnostics, including that of the non-Maxwellian
  κ-distributions, in several structures observed in the solar corona
  by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on board the
  Hinode spacecraft. To prevent uncertainties due to the in-flight
  calibration of EIS, we selected spectral atlases observed shortly
  after the launch of the mission. One spectral atlas contains an
  observation of an active region, while the other is an off-limb
  quiet-Sun region. To minimize the uncertainties of the diagnostics,
  we rely only on strong lines and average the signal over a spatial
  area within selected structures. Multiple plasma parameters are
  diagnosed, such as the electron density, the differential emission
  measure, and the non-Maxwellian parameter κ. To do that, we use
  a simple, well-converging iterative scheme based on refining the
  initial density estimates via the differential emission measure
  (DEM) and κ. We find that while the quiet-Sun spectra are consistent
  with a Maxwellian distribution, the coronal loops and moss observed
  within the active region are strongly non-Maxwellian with κ ⪅
  3. These results were checked by calculating synthetic ratios using
  DEMs obtained as a function of κ. Ratios predicted using the DEMs
  assuming κ-distributions converged to the ratios observed in the
  quiet Sun and coronal loops. To our knowledge, this work presents a
  strong evidence of the presence of different electron distributions
  between two physically distinct parts of the solar corona.

Title: Study of the spatial association between an active region
    jet and a nonthermal type III radio burst
Authors: Mulay, Sargam M.; Sharma, Rohit; Valori, Gherardo; Vásquez,
   Alberto M.; Del Zanna, Giulio; Mason, Helen; Oberoi, Divya
Bibcode: 2019A&A...632A.108M
Altcode:
  <BR /> Aims: We aim to investigate the spatial location of the source
  of an active region (AR) jet and its relation with associated nonthermal
  type III radio emission. <BR /> Methods: An emission measure (EM) method
  was used to study the thermodynamic nature of the AR jet. The nonthermal
  type III radio burst observed at meterwavelength was studied using
  the Murchison Widefield Array (MWA) radio imaging and spectroscopic
  data. The local configuration of the magnetic field and the connectivity
  of the source region of the jet with open magnetic field structures was
  studied using a nonlinear force-free field (NLFFF) extrapolation and
  potential field source surface (PFSS) extrapolation respectively. <BR
  /> Results: The plane-of-sky velocity of the AR jet was found to be
  ∼136 km s<SUP>-1</SUP>. The EM analysis confirmed the presence of
  low temperature 2 MK plasma for the spire, whereas hot plasma, between
  5 and 8 MK, was present at the footpoint region which also showed the
  presence of Fe XVIII emission. A lower limit on the electron number
  density was found to be 1.4 × 10<SUP>8</SUP> cm<SUP>-3</SUP> for the
  spire and 2.2 × 10<SUP>8</SUP> cm<SUP>-3</SUP> for the footpoint. A
  temporal and spatial correlation between the AR jet and nonthermal
  type III burst confirmed the presence of open magnetic fields. An NLFFF
  extrapolation showed that the photospheric footpoints of the null point
  were anchored at the location of the source brightening of the jet. The
  spatial location of the radio sources suggests an association with the
  extrapolated closed and open magnetic fields although strong propagation
  effects are also present. <BR /> Conclusions: The multi-scale analysis
  of the field at local, AR, and solar scales confirms the interlink
  between different flux bundles involved in the generation of the type
  III radio signal with flux transferred from a small coronal hole to the
  periphery of the sunspot via null point reconnection with an emerging
  structure. <P />The movie associated to Fig. 4 is available at <A
  href="https://www.aanda.org/10.1051/0004-6361/201936369/olm">https://www.aanda.org</A>

Title: Hinode EIS line widths in the quiet corona up to 1.5
    R<SUB>⊙</SUB>
Authors: Del Zanna, G.; Gupta, G. R.; Mason, H. E.
Bibcode: 2019A&A...631A.163D
Altcode: 2019arXiv190509783D
  We present an analysis of several Hinode Extreme-ultraviolet Imaging
  Spectrometer (EIS) observations of coronal line widths in the quiet Sun,
  up to 1.5 R<SUB>⊙</SUB> radial distances. Significant variations are
  found, which indicates no damping of Alfvén waves in the quiescent
  corona. However, the uncertainties in estimating the instrumental
  width mean that a firm conclusion cannot be reached. We present a
  discussion of various EIS instrumental issues and suggest that the
  strongest lines, from Fe XII at 193.5 Å and 195.1 Å, have anomalous
  instrumental widths. We also show how line widths in EIS are uncertain
  when the signal is low, and that the instrumental variation along
  the slit is also uncertain. We also find an anomalous decrease (up
  to 40%) in the intensities of these lines in many off-limb and active
  region observations, and provide evidence that this is due to opacity
  effects. We find that the most reliable measurements are obtained from
  the weaker lines.

Title: Exploring the damping of Alfvén waves along a long off-limb
    coronal loop, up to 1.4 R<SUB>⊙</SUB>
Authors: Gupta, G. R.; Del Zanna, G.; Mason, H. E.
Bibcode: 2019A&A...627A..62G
Altcode: 2019arXiv190508194G
  The Alfvén wave energy flux in the corona can be explored using the
  electron density and velocity amplitude of the waves. The velocity
  amplitude of Alfvén waves can be obtained from the non-thermal velocity
  of spectral line profiles. Previous calculations of the Alfvén wave
  energy flux with height in active regions and polar coronal holes have
  provided evidence for the damping of Alfvén waves with height. We
  present off-limb Hinode Extreme-ultraviolet Imaging Spectrometer (EIS)
  observations of a long coronal loop up to 1.4 R<SUB>⊙</SUB>. We
  obtained the electron density along the loop and found the loop to be
  almost in hydrostatic equilibrium. We obtained the temperature using
  the emission measure-loci (EM-loci) method and found the loop to be
  isothermal across, as well as along, the loop with a temperature of
  about 1.37 MK. We significantly improve the estimate of non-thermal
  velocities over previous studies by using the estimated ion (equal to
  electron) temperature. Estimates of electron densities are improved
  using the significant updates of the CHIANTI v.8 atomic data. More
  accurate measurements of propagating Alfvén wave energy along the
  coronal loop and its damping are presented up to distances of 1.4
  R<SUB>⊙</SUB>, further than have been previously explored. The
  Alfvén wave energy flux obtained could contribute to a significant
  part of the coronal losses due to radiation along the loop.

Title: Signatures of the non-Maxwellian κ-distributions in optically
    thin line spectra. II. Synthetic Fe XVII-XVIII X-ray coronal spectra
    and predictions for the Marshall Grazing-Incidence X-ray Spectrometer
    (MaGIXS)
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Del Zanna, Giulio;
   Mason, Helen E.; Golub, Leon L.; Winebarger, Amy R.; Savage, Sabrina L.
Bibcode: 2019A&A...626A..88D
Altcode: 2019arXiv190510356D
  <BR /> Aims: We investigated the possibility of diagnosing the degree of
  departure from the Maxwellian distribution using the Fe XVII-Fe XVIII
  spectra originating in plasmas in collisional ionization equilibrium,
  such as in the cores of solar active regions or microflares. <BR />
  Methods: The original collision strengths for excitation are integrated
  over the non-Maxwellian electron κ-distributions characterized by a
  high-energy tail. Synthetic X-ray emission line spectra were calculated
  for a range of temperatures and κ. We focus on the 6-24 Å spectral
  range to be observed by the upcoming Marshall Grazing-Incidence X-ray
  Spectrometer MaGIXS. <BR /> Results: We find that many line intensity
  ratios are sensitive to both T and κ. Best diagnostic options are
  provided if a ratio involving both Fe XVII and Fe XVIII is combined
  with another ratio involving lines formed within a single ion. The
  sensitivity of such diagnostics to κ is typically a few tens of per
  cent. Much larger sensitivity, of about a factor of two to three, can
  be obtained if the Fe XVIII 93.93 Å line observed by SDO/AIA is used
  in conjuction with the X-ray lines. <BR /> Conclusions: We conclude
  that the MaGIXS instrument is well-suited for detection of departures
  from the Maxwellian distribution, especially in active region cores.

Title: Flare-related Recurring Active Region Jets: Evidence for Very
    Hot Plasma
Authors: Mulay, Sargam M.; Matthews, Sarah; Hasegawa, Takahiro;
   Del Zanna, Giulio; Mason, Helen; Shimizu, Toshifumi
Bibcode: 2018SoPh..293..160M
Altcode:
  We present a study of two active region jets (AR jets) that are
  associated with two C-class X-ray flares. The recurrent, homologous
  jets originated from the northern periphery of a sunspot. We
  confirm flare-like temperatures at the footpoints of these jets using
  spectroscopic observations of Fe XXIII (263.76 Å) and Fe XXIV (255.11
  Å) emission lines. The emission measure loci method was used to obtain
  an isothermal temperature, and the results show a decrease (17.7 to 13.6
  MK) in the temperature during the decay phase of the C 3.0 flare. The
  electron number densities at the footpoints were found to range from
  1.7 ×10<SUP>10</SUP> to 2.0 ×10<SUP>11</SUP>cm−<SUP>3</SUP> using
  the Fe XIV line pair ratio. Nonthermal velocities were found to range
  from 34 - 100 km/s for Fe XXIV and 51 - 89 km/s for Fe XXIII. The
  plane-of-sky velocities were calculated to be 462 ±21 and 228 ±23
  km/s for the two jets using the Atmospheric Imaging Assembly (AIA)
  171 Å channel. The AIA light curves of the jet footpoint regions
  confirmed the temporal and spatial correlation between the two X-ray
  flares and the jet footpoint emission. The Gamma-ray Burst Monitor (GBM)
  also confirmed superhot plasma of 27 (25) MK with a nonthermal energy
  of 2.38 ×10<SUP>26</SUP> (2.87 ×10<SUP>27</SUP>) ergs−<SUP>1</SUP>
  in the jet footpoint region during the rise (peak) phase of one of the
  flares. The temperatures of the jet footpoint regions obtained from
  EIS agree very well (within an uncertainty of 20%) with temperatures
  obtained from the Geostationary Environmental Operational Satellite
  (GOES) flux ratios. These results provide clear evidence for very hot
  plasma (&gt;10 MK) at the footpoints of the flare-related jets, and
  they confirm the heating and cooling of the plasma during the flares.

Title: Solar UV and X-ray spectral diagnostics
Authors: Del Zanna, Giulio; Mason, Helen E.
Bibcode: 2018LRSP...15....5D
Altcode: 2018arXiv180901618D
  X-ray and ultraviolet (UV) observations of the outer solar atmosphere
  have been used for many decades to measure the fundamental parameters
  of the solar plasma. This review focuses on the optically thin
  emission from the solar atmosphere, mostly found at UV and X-ray (XUV)
  wavelengths, and discusses some of the diagnostic methods that have
  been used to measure electron densities, electron temperatures,
  differential emission measure (DEM), and relative chemical
  abundances. We mainly focus on methods and results obtained from
  high-resolution spectroscopy, rather than broad-band imaging. However,
  we note that the best results are often obtained by combining imaging
  and spectroscopic observations. We also mainly focus the review on
  measurements of electron densities and temperatures obtained from single
  ion diagnostics, to avoid issues related to the ionisation state of
  the plasma. We start the review with a short historical introduction
  on the main XUV high-resolution spectrometers, then review the basics
  of optically thin emission and the main processes that affect the
  formation of a spectral line. We mainly discuss plasma in equilibrium,
  but briefly mention non-equilibrium ionisation and non-thermal electron
  distributions. We also summarise the status of atomic data, which
  are an essential part of the diagnostic process. We then review the
  methods used to measure electron densities, electron temperatures,
  the DEM, and relative chemical abundances, and the results obtained
  for the lower solar atmosphere (within a fraction of the solar radii),
  for coronal holes, the quiet Sun, active regions and flares.

Title: The Marshall Grazing Incidence X-ray Spectrometer (MaGIXS)
Authors: Winebarger, A. R.; Savage, S. L.; Kobayashi, K.; Champey,
   P. R.; McKenzie, D. E.; Golub, L.; Testa, P.; Reeves, K.; Cheimets,
   P.; Cirtain, J. W.; Walsh, R. W.; Bradshaw, S. J.; Warren, H.; Mason,
   H. E.; Del Zanna, G.
Bibcode: 2017AGUFMSH44A..06W
Altcode:
  For over four decades, X-ray, EUV, and UV spectral observations have
  been used to measure physical properties of the solar atmosphere. At
  wavelengths below 10 nm, however, observations of the solar corona
  with simultaneous spatial and spectral resolution are limited,
  and not since the late 1970's have spatially resolved solar X-ray
  spectra been measured. Because the soft X-ray regime is dominated
  by emission lines formed at high temperatures, X-ray spectroscopic
  techniques yield insights to fundamental physical processes that are
  not accessible by any other means. Using a novel implementation of
  corrective optics, the Marshall Grazing Incidence X-ray Spectrometer
  (MaGIXS) will measure, for the first time, the solar spectrum from 0.6-
  2.4 nm with a 6 arcsec resolution over an 8 arcmin slit. The MaGIXS
  mission will address on of the fundamental problems of coronal physics:
  the nature of coronal heating. There are several observables in the
  MaGIXS wavelength range that will constrain the heating frequency and
  hence discriminate between competing coronal heating theories. In this
  presentation, we will present the MaGIXS scientific motivation and
  provide an update on instrument development. MaGIXS will be launched
  from White Sands Missile Range in the summer of 2019.

Title: Non-thermal distributions and energy transport in the solar
    flares
Authors: Matthews, Sarah; del Zanna, Guilio; Calcines, Ariadna;
   Mason, Helen; Mathioudakis, Mihalis; Culhane, Len; Harra, Louise;
   van Driel-Gesztelyi, Lidia; Green, Lucie; Long, David; Baker, Deb;
   Valori, Gherardo
Bibcode: 2017arXiv171200773M
Altcode:
  Determining the energy transport mechanisms in flares remains a central
  goal in solar flares physics that is still not adequately answered
  by the 'standard flare model'. In particular, the relative roles of
  particles and/or waves as transport mechanisms, the contributions of low
  energy protons and ions to the overall flare budget, and the limits of
  low energy non-thermal electron distribution are questions that still
  cannot be adequately reconciled with current instrumentation. In this
  'White Paper' submitted in response to the call for inputs to the Next
  Generation Solar Physics Mission review process initiated by JAXA,
  NASA and ESA in 2016, we outline the open questions in this area and
  possible instrumentation that could provide the required observations
  to help answer these and other flare-related questions.

Title: Cool and hot emission in a recurring active region jet
Authors: Mulay, Sargam M.; Del Zanna, Giulio; Mason, Helen
Bibcode: 2017A&A...606A...4M
Altcode:
  <BR /> Aims: We present a thorough investigation of the cool and hot
  temperature components in four recurring active region jets observed
  on July 10, 2015 using the Atmospheric Imaging Assembly (AIA),
  X-ray Telescope (XRT), and Interface Region Imaging Spectrograph
  (IRIS) instruments. <BR /> Methods: A differential emission measure
  (DEM) analysis was performed on areas in the jet spire and footpoint
  regions by combining the IRIS spectra and the AIA observations. This
  procedure better constrains the low temperature DEM values by adding
  IRIS spectral lines. Plasma parameters, such as Doppler velocities,
  electron densities, nonthermal velocities and a filling factor
  were also derived from the IRIS spectra. <BR /> Results: In the
  DEM analysis, significant cool emission was found in the spire and
  the footpoint regions. The hot emission was peaked at log T [K] =
  5.6-5.9 and 6.5 respectively. The DEM curves show the presence of
  hot plasma (T = 3 MK) in the footpoint region. We confirmed this
  result by estimating the Fe XVIII emission from the AIA 94 Å channel
  which was formed at an effective temperature of log T [K] = 6.5. The
  average XRT temperatures were also found to be in agreement with log
  T [K] = 6.5. The emission measure (EM) was found to be three orders
  of magnitude higher in the AIA-IRIS DEM compared with that obtained
  using only AIA. The O IV (1399/1401 Å) electron densities were found
  to be 2.0×10<SUP>10</SUP> cm<SUP>-3</SUP> in the spire and 7.6 ×
  10<SUP>10</SUP> cm<SUP>-3</SUP> in the footpoint. Different threads
  along the spire show different plane-of-sky velocities both in the
  lower corona and transition region. Doppler velocities of 32 km
  s<SUP>-1</SUP> (blueshifted) and 13 km s<SUP>-1</SUP> (redshifted)
  were obtained in the spire and footpoint, respectively from the
  Si IV 1402.77 Å spectral line. Nonthermal velocities of 69 and 53
  km s<SUP>-1</SUP> were recorded in the spire and footpoint region,
  respectively. We obtained a filling factor of 0.1 in the spire at
  log T [K] = 5. <BR /> Conclusions: The recurrent jet observations
  confirmed the presence of significant cool emission co-spatial with the
  coronal emission. <P />The movie attached to Fig. 3 is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201730429/olm">http://www.aanda.org</A>

Title: Spectroscopy of Very Hot Plasma in Non-flaring Parts of a
Solar Limb Active Region: Spatial and Temporal Properties
Authors: Parenti, Susanna; del Zanna, Giulio; Petralia, Antonino;
   Reale, Fabio; Teriaca, Luca; Testa, Paola; Mason, Helen E.
Bibcode: 2017ApJ...846...25P
Altcode: 2017arXiv170708445P
  In this work we investigate the thermal structure of an off-limb
  active region (AR) in various non-flaring areas, as it provides key
  information on the way these structures are heated. In particular,
  we concentrate on the very hot component (&gt; 3 {MK}) as it is a
  crucial element to distinguish between different heating mechanisms. We
  present an analysis using Fe and Ca emission lines from both the
  Solar Ultraviolet Measurement of Emitted Radiation (SUMER) on board
  the Solar and Heliospheric Observatory (SOHO) and the EUV Imaging
  Spectrometer (EIS) on board Hinode. A data set covering all ionization
  stages from Fe x to Fe xix has been used for the thermal analysis
  (both differential emission measure and emission measure, EM). Ca
  xiv is used for the SUMER-EIS radiometric cross calibration. We show
  that the very hot plasma is present and persistent almost everywhere
  in the core of the limb AR. The off-limb AR is clearly structured in
  Fe xviii. Almost everywhere, the EM analysis reveals plasma at 10 MK
  (visible in Fe xix emission), which is down to 0.1% of EM of the main
  3 {MK} plasma. We estimate the power-law index of the hot tail of
  the EM to be between -8.5 and -4.4. However, the question about the
  possible existence of a small minor peak at around 10 {MK} remains
  open. The absence in some part of the AR of the Fe xix and Fe xxiii
  lines (which fall into our spectral range) enables us to determine
  an upper limit on the EM at these temperatures. Our results include
  a new Ca xiv 943.59 Å atomic model.

Title: Nonequilibrium Processes in the Solar Corona, Transition
    Region, Flares, and Solar Wind (Invited Review)
Authors: Dudík, Jaroslav; Dzifčáková, Elena; Meyer-Vernet, Nicole;
   Del Zanna, Giulio; Young, Peter R.; Giunta, Alessandra; Sylwester,
   Barbara; Sylwester, Janusz; Oka, Mitsuo; Mason, Helen E.; Vocks,
   Christian; Matteini, Lorenzo; Krucker, Säm; Williams, David R.;
   Mackovjak, Šimon
Bibcode: 2017SoPh..292..100D
Altcode: 2017arXiv170603396D
  We review the presence and signatures of the non-equilibrium processes,
  both non-Maxwellian distributions and non-equilibrium ionization, in
  the solar transition region, corona, solar wind, and flares. Basic
  properties of the non-Maxwellian distributions are described
  together with their influence on the heat flux as well as on the
  rates of individual collisional processes and the resulting optically
  thin synthetic spectra. Constraints on the presence of high-energy
  electrons from observations are reviewed, including positive detection
  of non-Maxwellian distributions in the solar corona, transition
  region, flares, and wind. Occurrence of non-equilibrium ionization
  is reviewed as well, especially in connection to hydrodynamic and
  generalized collisional-radiative modeling. Predicted spectroscopic
  signatures of non-equilibrium ionization depending on the assumed
  plasma conditions are summarized. Finally, we discuss the future
  remote-sensing instrumentation that can be used for the detection of
  these non-equilibrium phenomena in various spectral ranges.

Title: Analysis and modelling of recurrent solar flares observed
    with Hinode/EIS on March 9, 2012
Authors: Polito, V.; Del Zanna, G.; Valori, G.; Pariat, E.; Mason,
   H. E.; Dudík, J.; Janvier, M.
Bibcode: 2017A&A...601A..39P
Altcode: 2016arXiv161203504P
  Three homologous C-class flares and one last M-class flare were observed
  by both the Solar Dynamics Observatory (SDO) and the Hinode EUV Imaging
  Spectrometer (EIS) in the AR 11429 on March 9, 2012. All the recurrent
  flares occurred within a short interval of time (less than 4 h),
  showed very similar plasma morphology and were all confined, until the
  last one when a large-scale eruption occurred. The C-class flares are
  characterized by the appearance, at approximatively the same locations,
  of two bright and compact footpoint sources of ≈3-10 MK evaporating
  plasma, and a semi-circular ribbon. During all the flares, the
  continuous brightening of a spine-like hot plasma (≈10 MK) structure
  is also observed. Spectroscopic observations with Hinode/EIS are used to
  measure and compare the blueshift velocities in the Fe xxiii emission
  line and the electron number density at the flare footpoints for each
  flare. Similar velocities, of the order of 150-200 km s<SUP>-1</SUP>,
  are observed during the C2.0 and C4.7 confined flares, in agreement
  with the values reported by other authors in the study of the last M1.8
  class flare. On the other hand, lower electron number densities and
  temperatures tend to be observed in flares with lower peak soft X-ray
  flux. In order to investigate the homologous nature of the flares, we
  performed a non-linear force-free field (NLFFF) extrapolation of the 3D
  magnetic field configuration in the corona. The NLFFF extrapolation and
  the Quasi-Separatrix Layers (QSLs) provide the magnetic field context
  which explains the location of the kernels, spine-like hot plasma and
  semi-circular brightenings observed in the (non-eruptive) flares. Given
  the absence of a coronal null point, we argue that the homologous
  flares were all generated by the continuous recurrence of bald patch
  reconnection. <P />The movie associated to Fig. 2 is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201629703/olm">http://www.aanda.org</A>

Title: Fan Loops Observed by IRIS, EIS, and AIA
Authors: Ghosh, Avyarthana; Tripathi, Durgesh; Gupta, G. R.; Polito,
   Vanessa; Mason, Helen E.; Solanki, Sami K.
Bibcode: 2017ApJ...835..244G
Altcode: 2017arXiv170101617G
  A comprehensive study of the physical parameters of active region fan
  loops is presented using the observations recorded with the Interface
  Region Imaging Spectrometer (IRIS), the EUV Imaging Spectrometer (EIS)
  on board Hinode, and the Atmospheric Imaging Assembly (AIA) and the
  Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics
  Observatory (SDO). The fan loops emerging from non-flaring AR 11899
  (near the disk center) on 2013 November 19 are clearly discernible in
  AIA 171 Å images and in those obtained in Fe viii and Si vii images
  using EIS. Our measurements of electron densities reveal that the
  footpoints of these loops are at an approximately constant pressure
  with electron densities of {log} {N}<SUB>e</SUB>=10.1 cm<SUP>-3</SUP> at
  {log} [T/K]=5.15 (O IV), and {log} {N}<SUB>e</SUB>=8.9 cm<SUP>-3</SUP>
  at {log} [T/K]=6.15 (Si x). The electron temperature diagnosed
  across the fan loops by means of EM-Loci suggest that two temperature
  components exist at {log} [T/K]=4.95 and 5.95 at the footpoints. These
  components are picked up by IRIS lines and EIS lines, respectively. At
  higher heights, the loops are nearly isothermal at {log} [T/K]=5.95,
  which remained constant along the loop. The measurement of the Doppler
  shift using IRIS lines suggests that the plasma at the footpoints of
  these loops is predominantly redshifted by 2-3 km s<SUP>-1</SUP> in C
  II, 10-15 km s<SUP>-1</SUP> in Si IV, and 15-20 km s<SUP>-1</SUP> in O
  IV, reflecting the increase in the speed of downflows with increasing
  temperature from {log} [T/K]=4.40 to 5.15. These observations can
  be explained by low-frequency nanoflares or impulsive heating, and
  provide further important constraints on the modeling of the dynamics
  of fan loops.

Title: Temperature and density structure of a recurring active
    region jet
Authors: Mulay, Sargam M.; Del Zanna, Giulio; Mason, Helen
Bibcode: 2017A&A...598A..11M
Altcode: 2016arXiv160908472M
  <BR /> Aims: We present a study of a recurring jet observed on
  October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on
  board the Solar Dynamic Observatory, the X-ray Telescope (XRT)
  and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the
  physical parameters of the jet that are obtained using imaging and
  spectroscopic observations, such as density, differential emission
  measure, peak temperature, velocity, and filling factor. <BR /> Methods:
  A differential emission measure (DEM) analysis was performed at the
  region of the jet spire and the footpoint using EIS observations
  and also by combining AIA and XRT observations. The resulting
  EIS DEM curves were compared to those obtained with AIA-XRT. The
  DEM curves were used to create synthetic spectra with the CHIANTI
  atomic database. The predicted total count rates for each AIA channel
  were compared with the observed count rates. The effects of varying
  elemental abundances and the temperature range for the DEM inversion
  were investigated. Spectroscopic diagnostics were used to obtain
  an electron number density distribution for the jet spire and the
  jet footpoint. <BR /> Results: The plasma along the line of sight
  in the jet spire and jet footpoint was found to be peak at 2.0 MK
  (log T [K] = 6.3). We calculated electron densities using the Fe XII
  (λ186/λ195) line ratio in the region of the spire (N<SUB>e</SUB>
  = 7.6 × 10<SUP>10</SUP> cm<SUP>-3</SUP>) and the footpoint (1.1
  × 10<SUP>11</SUP> cm<SUP>-3</SUP>). The plane-of-sky velocity of
  the jet is found to be 524 km s<SUP>-1</SUP>. The resulting EIS DEM
  values are in good agreement with those obtained from AIA-XRT. The
  synthetic spectra contributing to each AIA channel confirms the
  multi-thermal nature of the AIA channels in both regions. There is
  no indication of high temperatures, such as emission from Fe XVII
  (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of
  the jet footpoint, synthetic spectra predict weak contributions from
  Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation,
  we confirmed emission from the Fe XVIII (93.932 Å) line in the AIA
  94 Å channel in the region of the footpoint. We also found good
  agreement between the estimated and predicted Fe XVIII count rates. A
  study of the temporal evolution of the jet footpoint and the presence
  of high-temperature emission from the Fe XVIII (λ93.932) (log T [K]
  = 6.85) line leads us to conclude that the hot component in the jet
  footpoint was present initially and that the jet had cooled down by the
  time EIS observed it. <P />Two movies attached to Fig. 2 are available
  at <A href="http://www.aanda.org">http://www.aanda.org</A>

Title: Can the non-Maxwellian kappa-distributions be diagnosed in
    the solar corona?
Authors: Dudík, J.; Dzifcakova, E.; Del Zanna, G.; Mackovjak, Š.;
   Mason, H. E.
Bibcode: 2016AGUFMSH21D2555D
Altcode:
  We report on the search of signatures of the non-Maxwellian
  kappa-distributions in the emission line spectra of the solar
  corona. A survey of coronal lines is performed for single-ion and
  multi-ion diagnostics using ions spanning the temperature range of
  0.5 - 6 MK. State-of-art excitation cross-sections are integrated
  directly to obtain the corresponding non-Maxwellian excitation and
  deexcitation rates. Ionization and recombination rates are obtained by
  approximative methods. We find that there are only a few good diagnostic
  options. This is due to majority of lines being formed from similar
  energy levels. The best diagnostic options rely on lines formed at
  different excitation tresholds, i.e., at different wavelengths. This
  highlights the importance of absolute intensity calibration of
  space-borne spectrometers. The applicability of these methods is
  demonstrated on analysis of a dedicated extreme-ultraviolet observations
  made in the Fe XI-XIII lines by the Hinode/EIS satellite during HOP
  226. The observations are performed in an active region containing a
  filament and several coronal loops. A transient coronal loop appears
  at the foot of a filament and is preceded by activity within this
  filament. EIS spectra are used to diagnose the electron density,
  but also reveal that the transient loop is highly non-Maxwellian,
  characterized by a kappa=2 distribution. We discuss the methods for
  separation the non-Maxwellian effects from the effects of plasma
  multi-thermality arising due to finite spatial resolution, as well
  as the effect of kappa-distributions on the degree of multithermality
  diagnosed in various observed coronal features.

Title: Solar Coronal Jets: Observations, Theory, and Modeling
Authors: Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.;
   Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.;
   DeVore, C. R.; Archontis, V.; Török, T.; Mason, H.; Curdt, W.;
   Meyer, K.; Dalmasse, K.; Matsui, Y.
Bibcode: 2016SSRv..201....1R
Altcode: 2016arXiv160702108R; 2016SSRv..tmp...31R
  Coronal jets represent important manifestations of ubiquitous solar
  transients, which may be the source of significant mass and energy
  input to the upper solar atmosphere and the solar wind. While
  the energy involved in a jet-like event is smaller than that of
  "nominal" solar flares and coronal mass ejections (CMEs), jets
  share many common properties with these phenomena, in particular,
  the explosive magnetically driven dynamics. Studies of jets could,
  therefore, provide critical insight for understanding the larger,
  more complex drivers of the solar activity. On the other side of the
  size-spectrum, the study of jets could also supply important clues on
  the physics of transients close or at the limit of the current spatial
  resolution such as spicules. Furthermore, jet phenomena may hint to
  basic process for heating the corona and accelerating the solar wind;
  consequently their study gives us the opportunity to attack a broad
  range of solar-heliospheric problems.

Title: Density diagnostics derived from the O iv and S iv
    intercombination lines observed by IRIS
Authors: Polito, V.; Del Zanna, G.; Dudík, J.; Mason, H. E.; Giunta,
   A.; Reeves, K. K.
Bibcode: 2016A&A...594A..64P
Altcode: 2016arXiv160705072P
  The intensity of the O iv 2s<SUP>2</SUP> 2p
  <SUP>2</SUP>P-2s2p<SUP>2</SUP><SUP>4</SUP>P and S iv 3 s<SUP>2</SUP>
  3p <SUP>2</SUP>P-3s 3p<SUP>2</SUP><SUP>4</SUP> P intercombination lines
  around 1400 Å observed with the Interface Region Imaging Spectrograph
  (IRIS) provide a useful tool to diagnose the electron number density
  (N<SUB>e</SUB>) in the solar transition region plasma. We measure the
  electron number density in a variety of solar features observed by
  IRIS, including an active region (AR) loop, plage and brightening,
  and the ribbon of the 22-June-2015 M 6.5 class flare. By using the
  emissivity ratios of O iv and S iv lines, we find that our observations
  are consistent with the emitting plasma being near isothermal
  (logT[K] ≈ 5) and iso-density (N<SUB>e</SUB> ≈ 10<SUP>10.6</SUP>
  cm<SUP>-3</SUP>) in the AR loop. Moreover, high electron number
  densities (N<SUB>e</SUB> ≈ 10<SUP>13</SUP> cm<SUP>-3</SUP>) are
  obtained during the impulsive phase of the flare by using the S iv line
  ratio. We note that the S iv lines provide a higher range of density
  sensitivity than the O iv lines. Finally, we investigate the effects
  of high densities (N<SUB>e</SUB> ≳ 10<SUP>11</SUP> cm<SUP>-3</SUP>)
  on the ionization balance. In particular, the fractional ion
  abundances are found to be shifted towards lower temperatures for
  high densities compared to the low density case. We also explored the
  effects of a non-Maxwellian electron distribution on our diagnostic
  method. <P />The movie associated to Fig. 3 is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201628965/olm">http://www.aanda.org</A>

Title: Multiwavelength study of 20 jets that emanate from the
    periphery of active regions
Authors: Mulay, Sargam M.; Tripathi, Durgesh; Del Zanna, Giulio;
   Mason, Helen
Bibcode: 2016A&A...589A..79M
Altcode: 2016arXiv160200151M
  <BR /> Aims: We present a multiwavelength analysis of 20 EUV jets which
  occurred at the periphery of active regions close to sunspots. We
  discuss the physical parameters of the jets and their relation
  with other phenomena such as Hα surges, nonthermal type-III radio
  bursts and hard X-ray (HXR) emission. <BR /> Methods: These jets
  were observed between August 2010 and June 2013 by the Atmospheric
  Imaging Assembly (AIA) instrument that is onboard the Solar Dynamic
  Observatory (SDO). We selected events that were observed on the solar
  disk within +/-60° latitude. Using AIA wavelength channels that
  are sensitive to coronal temperatures, we studied the temperature
  distribution in the jets using the line of sight (LOS) differential
  emission measure (DEM) technique. We also investigated the role of the
  photospheric magnetic field using the LOS magnetogram data from the
  Helioseismic and Magnetic Imager (HMI) onboard SDO. <BR /> Results:
  It has been observed that most of the jets originated from the western
  periphery of active regions. Their lifetimes range from 5 to 39 min
  with an average of 18 min and their velocities range from 87 to 532
  km s<SUP>-1</SUP> with an average of 271 km s<SUP>-1</SUP>. All the
  jets are co-temporally associated with Hα surges. Most of the jets
  are co-temporal with nonthermal type-III radio bursts observed by the
  Wind/WAVES spacecraft in the frequency range from 20 kHz to 13 MHz. We
  confirm the source region of these bursts using the potential field
  source surface (PFSS) technique. Using Reuven Ramaty High Energy Solar
  Spectroscopic Imager (RHESSI) observations, we found that half of the
  jets produced HXR emission and they often shared the same source region
  as the HXR emission (6-12 keV). Ten out of 20 events showed that the
  jets originated in a region of flux cancellation and six jets in a
  region of flux emergence. Four events showed flux emergence and then
  cancellation during the jet evolution. DEM analyses showed that for
  most of the spires of the jets, the DEM peaked at around log T [K] =
  6.2/6.3 (~2 MK). In addition, we derived an emission measure and a lower
  limit of electron density at the location of the spire (jet 1: log EM =
  28.6, N<SUB>e</SUB> = 1.3 × 10<SUP>10</SUP> cm<SUP>-3</SUP>; jet 2:
  log EM = 28.0, N<SUB>e</SUB> = 8.6 × 10<SUP>9</SUP> cm<SUP>-3</SUP>)
  and the footpoint (jet 1 - log EM = 28.6, N<SUB>e</SUB> = 1.1 ×
  10<SUP>10</SUP> cm<SUP>-3</SUP>; jet 2: log EM = 28.1, N<SUB>e</SUB> =
  8.4 × 10<SUP>9</SUP> cm<SUP>-3</SUP>). These results are in agreement
  with those obtained earlier by studying individual active region
  jets. <BR /> Conclusions: The observation of flux cancellation, the
  association with HXR emission and emission of nonthermal type-III
  radio bursts, suggest that the initiation and therefore, heating
  is taking place at the base of the jet. This is also supported by
  the high temperature plasma revealed by the DEM analysis in the jet
  footpoint (peak in the DEM at log T [K] = 6.5). Our results provide
  substantial constraints for theoretical modeling of the jets and their
  thermodynamic nature. <P />Movies are available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201527473/olm">http://www.aanda.org</A>

Title: Slipping Magnetic Reconnection, Chromospheric Evaporation,
    Implosion, and Precursors in the 2014 September 10 X1.6-Class
    Solar Flare
Authors: Dudík, Jaroslav; Polito, Vanessa; Janvier, Miho; Mulay,
   Sargam M.; Karlický, Marian; Aulanier, Guillaume; Del Zanna, Giulio;
   Dzifčáková, Elena; Mason, Helen E.; Schmieder, Brigitte
Bibcode: 2016ApJ...823...41D
Altcode: 2016arXiv160306092D
  We investigate the occurrence of slipping magnetic reconnection,
  chromospheric evaporation, and coronal loop dynamics in the 2014
  September 10 X-class flare. Slipping reconnection is found to be present
  throughout the flare from its early phase. Flare loops are seen to slip
  in opposite directions toward both ends of the ribbons. Velocities
  of 20-40 km s<SUP>-1</SUP> are found within time windows where the
  slipping is well resolved. The warm coronal loops exhibit expanding and
  contracting motions that are interpreted as displacements due to the
  growing flux rope that subsequently erupts. This flux rope existed and
  erupted before the onset of apparent coronal implosion. This indicates
  that the energy release proceeds by slipping reconnection and not via
  coronal implosion. The slipping reconnection leads to changes in the
  geometry of the observed structures at the Interface Region Imaging
  Spectrograph slit position, from flare loop top to the footpoints in
  the ribbons. This results in variations of the observed velocities of
  chromospheric evaporation in the early flare phase. Finally, it is found
  that the precursor signatures, including localized EUV brightenings as
  well as nonthermal X-ray emission, are signatures of the flare itself,
  progressing from the early phase toward the impulsive phase, with
  the tether-cutting being provided by the slipping reconnection. The
  dynamics of both the flare and outlying coronal loops is found to be
  consistent with the predictions of the standard solar flare model in
  three dimensions.

Title: The CHIANTI atomic database
Authors: Young, P. R.; Dere, K. P.; Landi, E.; Del Zanna, G.; Mason,
   H. E.
Bibcode: 2016JPhB...49g4009Y
Altcode: 2015arXiv151205620Y
  The freely available CHIANTI atomic database was first released
  in 1996 and has had a huge impact on the analysis and modeling of
  emissions from astrophysical plasmas. It contains data and software
  for modeling optically thin atom and positive ion emission from low
  density (≲10<SUP>13</SUP> cm<SUP>-3</SUP>) plasmas from x-ray to
  infrared wavelengths. A key feature is that the data are assessed
  and regularly updated, with version 8 released in 2015. Atomic data
  for modeling the emissivities of 246 ions and neutrals are contained
  in CHIANTI, together with data for deriving the ionization fractions
  of all elements up to zinc. The different types of atomic data are
  summarized here and their formats discussed. Statistics on the impact
  of CHIANTI to the astrophysical community are given and examples of
  the diverse range of applications are presented.

Title: Simultaneous IRIS and Hinode/EIS Observations and Modelling
    of the 2014 October 27 X2.0 Class Flare
Authors: Polito, V.; Reep, J. W.; Reeves, K. K.; Simões, P. J. A.;
   Dudík, J.; Del Zanna, G.; Mason, H. E.; Golub, L.
Bibcode: 2016ApJ...816...89P
Altcode: 2015arXiv151206378P
  We present a study of the X2-class flare which occurred on 2014 October
  27 and was observed with the Interface Region Imaging Spectrograph
  (IRIS) and the EUV Imaging Spectrometer (EIS) on board the Hinode
  satellite. Thanks to the high cadence and spatial resolution of the IRIS
  and EIS instruments, we are able to compare simultaneous observations
  of the Fe xxi 1354.08 Å and Fe xxiii 263.77 Å high-temperature
  emission (≳10 MK) in the flare ribbon during the chromospheric
  evaporation phase. We find that IRIS observes completely blueshifted
  Fe xxi line profiles, up to 200 km s<SUP>-1</SUP> during the rise
  phase of the flare, indicating that the site of the plasma upflows is
  resolved by IRIS. In contrast, the Fe xxiii line is often asymmetric,
  which we interpret as being due to the lower spatial resolution of
  EIS. Temperature estimates from SDO/AIA and Hinode/XRT show that hot
  emission (log(T[K]) &gt; 7.2) is first concentrated at the footpoints
  before filling the loops. Density-sensitive lines from IRIS and
  EIS give estimates of electron number density of ≳10<SUP>12</SUP>
  cm<SUP>-3</SUP> in the transition region lines and 10<SUP>10</SUP>
  cm<SUP>-3</SUP> in the coronal lines during the impulsive phase. In
  order to compare the observational results against theoretical
  predictions, we have run a simulation of a flare loop undergoing
  heating using the HYDRAD 1D hydro code. We find that the simulated
  plasma parameters are close to the observed values that are obtained
  with IRIS, Hinode, and AIA. These results support an electron beam
  heating model rather than a purely thermal conduction model as the
  driving mechanism for this flare.

Title: On the validity of the ICFT R-matrix method: Fe XIV
Authors: Del Zanna, G.; Badnell, N. R.; Fernández-Menchero, L.;
   Liang, G. Y.; Mason, H. E.; Storey, P. J.
Bibcode: 2015MNRAS.454.2909D
Altcode:
  Recently, Aggarwal &amp; Keenan published a Dirac R-matrix (DARC)
  calculation for the electron-impact excitation of Fe XIV. A 136-level
  configuration-interaction/close-coupling (CI/CC) expansion was
  adopted. Comparisons with earlier calculations, obtained by Liang
  et al. with the intermediate coupling frame transformation (ICFT)
  R-matrix method, showed significant discrepancies. One of the main
  differences was that the Liang et al. effective collision strengths
  were consistently larger. Aggarwal &amp; Keenan suggested various
  possible causes for the differences. We discuss them in detail here. We
  have carried out an ICFT R-matrix calculation with the same 136-level
  CI/CC expansion adopted by Aggarwal &amp; Keenan, and compared the
  results with theirs and with those of Liang et al., which employed a
  much larger CI/CC expansion. We find that the main differences arise
  because of the different CC and CI expansions, and not because of the
  use of the ICFT method, as suggested by Aggarwal &amp; Keenan. The
  significant increase in the effective collision strengths obtained by
  Liang et al. is mainly due to the extra resonances that are present
  because of the larger target expansion.

Title: CHIANTI - An atomic database for emission lines. Version 8
Authors: Del Zanna, G.; Dere, K. P.; Young, P. R.; Landi, E.; Mason,
   H. E.
Bibcode: 2015A&A...582A..56D
Altcode: 2015arXiv150807631D
  We present version 8 of the CHIANTI database. This version includes
  a large amount of new data and ions, which represent a significant
  improvement in the soft X-ray, extreme UV (EUV) and UV spectral
  regions, which several space missions currently cover. New data for
  neutrals and low charge states are also added. The data are assessed,
  but to improve the modelling of low-temperature plasma the effective
  collision strengths for most of the new datasets are not spline-fitted
  as previously, but are retained as calculated. This required a change
  of the format of the CHIANTI electron excitation files. The format
  of the energy files has also been changed. Excitation rates between
  all the levels are retained for most of the new datasets, so the data
  can in principle be used to model high-density plasma. In addition,
  the method for computing the differential emission measure used in
  the CHIANTI software has been changed.

Title: Slipping reconnection and chromospheric evaporation in the
    10 September 2014 flare
Authors: Dudík, Jaroslav; Janvier, Miho; Polito, Vanessa; Mulay,
   Sargam; Del Zanna, Giulio; Mason, Helen; Aulanier, Guillaume
Bibcode: 2015IAUGA..2252237D
Altcode:
  We study the occurrence of slipping reconnection in the long-duration
  X-class flare of 2014 September 10. From the start, the flare shows
  apparent slippage of hot Fe XXI flare loops observed in the 131A
  channel of SDO/AIA. Using the time-distance plots, we show that the
  slipping motion of the flare loops proceeds in counter directions in
  both flare ribbons. Simultaneous IRIS Fe XXI observations show the
  occurrence of chromospheric evaporation at brightening kernels that are
  involved in the slipping reconnection of AIA loops. This happens also
  during a flux-rope breakout accompanied by a faint 'magnetic implosion'
  of a coronal loop. Based on the 3D MHD flare model, we argue that the
  'implosion' is caused by the erupting flux rope pushing the neighbouring
  loops aside, with the low-lying loops being squeezed.

Title: Imaging and Spectroscopic Observations of a Transient Coronal
Loop: Evidence for the Non-Maxwellian K Distributions
Authors: Dudík, Jaroslav; Mackovjak, Šimon; Dzifčáková, Elena;
   Del Zanna, Giulio; Williams, David R.; Karlický, Marian; Mason,
   Helen E.; Lörinčík, Juraj; Kotrč, Pavel; Fárník, František;
   Zemanová, Alena
Bibcode: 2015ApJ...807..123D
Altcode: 2015arXiv150504333D
  We report on the Solar Dynamics Observatory/Atmospheric Imaging Assembly
  (AIA) and Hinode/EUV Imaging Spectrograph (EIS) observations of a
  transient coronal loop. The loop brightens up in the same location after
  the disappearance of an arcade formed during a B8.9-class microflare
  3 hr earlier. EIS captures this loop during its brightening phase,
  as observed in most of the AIA filters. We use the AIA data to study
  the evolution of the loop, as well as to perform the differential
  emission measure (DEM) diagnostics as a function of κ. The Fe xi-Fe
  xiii lines observed by EIS are used to perform the diagnostics of
  electron density and subsequently the diagnostics of κ. Using ratios
  involving the Fe xi 257.772 Å self-blend, we diagnose κ ≲ 2,
  i.e., an extremely non-Maxwellian distribution. Using the predicted
  Fe line intensities derived from the DEMs as a function of κ, we
  show that, with decreasing κ, all combinations of ratios of line
  intensities converge to the observed values, confirming the diagnosed
  κ ≲ 2. These results represent the first positive diagnostics of
  κ-distributions in the solar corona despite the limitations imposed
  by calibration uncertainties.

Title: Joint High Temperature Observation of a Small C6.5 Solar
    Flare With Iris/Eis/Aia
Authors: Polito, V.; Reeves, K. K.; Del Zanna, G.; Golub, L.; Mason,
   H. E.
Bibcode: 2015ApJ...803...84P
Altcode:
  We present the observation of a C6.5 class flare on 2014 February 3,
  obtained with the Interface Region Imaging Spectrograph (IRIS) and
  the EUV Imaging Spectrometer (EIS) on board HINODE. We follow the
  details of the impulsive phase with IRIS and the gradual decay phase
  with both IRIS and EIS. The IRIS Slit-Jaw Imager and Atmospheric
  Imaging Assembly (AIA) are used to precisely co-align the two sets
  of spectroscopic observations. Of particular interest is the Fe xxi
  1354.08 Å spectral line, which is the highest temperature emission
  (∼10 MK) observed in the IRIS wavelength range. We show the evolution
  of the Fe xxi profiles during the impulsive phase of the flare at the
  same ribbon location with a 75 s temporal cadence. Totally blueshifted
  (∼82 km {{s}<SUP>-1</SUP>}) profiles are found at the very early
  phase of the flare and gradually decrease in about 6 minutes. This
  result is consistent with 1D model predictions during chromospheric
  evaporation in flares. The blueshifted components also exhibit large
  non-thermal broadening, which decreases simultaneously with the
  blueshifted velocity. After the evaporation first occurs, the Fe xxi
  intensity progressively moves from the footpoints to the top of the
  hot flare loops seen in the AIA 131 Å images, where the emission is
  observed to be at rest and thermal. Emission measure estimates from
  IRIS/EIS/AIA observations during the gradual phase show isothermal loop
  top structures cooling from about 13.5 to 12 MK with electron densities
  of the order of ∼ 5-6× {{10}<SUP>10</SUP>} c{{m}<SUP>-3</SUP>}.

Title: Spectroscopic Observations of a Coronal Loop: Basic Physical
    Plasma Parameters Along the Full Loop Length
Authors: Gupta, G. R.; Tripathi, Durgesh; Mason, Helen E.
Bibcode: 2015ApJ...800..140G
Altcode: 2014arXiv1412.7428G
  Coronal loops are the basic structures of the solar transition
  region and corona. Understanding of the physical mechanisms behind
  the loop heating, plasma flows, and filling are still considered a
  major challenge in solar physics. The mechanism(s) should be able
  to supply mass to the corona from the chromosphere and to heat the
  plasma over 1 MK within a small distance of a few hundred kilometers
  from the chromosphere to the corona. This problem makes coronal loops
  an interesting target for detailed study. In this study, we focus on
  spectroscopic observations of a coronal loop observed in its full length
  in various spectral lines as recorded by the Extreme-ultraviolet Imaging
  Spectrometer on board Hinode. We derive physical plasma parameters such
  as electron density, temperature, pressure, column depth, and filling
  factors along the loop length from one footpoint to the another. The
  obtained parameters are used to infer whether the observed coronal loop
  is overdense or underdense with respect to gravitational stratification
  of the solar atmosphere. These new measurements of physical plasma
  parameters, from one footpoint to another, provide important constraints
  on the modeling of the mass and energy balance in coronal loops.

Title: The evolution of the emission measure distribution in the
    core of an active region
Authors: Del Zanna, Giulio; Tripathi, Durgesh; Mason, Helen;
   Subramanian, Srividya; O'Dwyer, Brendan
Bibcode: 2015A&A...573A.104D
Altcode: 2014arXiv1411.0128D
  We study the spatial distribution and evolution of the slope of the
  emission measure (EM) between 1 MK and 3 MK in the core of the active
  region (AR) NOAA 11193, first when it appeared near the central meridian
  and then again when it reappeared after a solar rotation. We use
  observations recorded by the Extreme-ultraviolet Imaging Spectrometer
  (EIS) aboard Hinode, with a new radiometric calibration. We also use
  observations from the Atmospheric Imaging Assembly (AIA) aboard the
  Solar Dynamics Observatory (SDO). We present the first spatially
  resolved maps of the EM slope in the 1-3 MK range within the core
  of the AR using several methods, either from approximations or from
  the differential emission measure (DEM). A significant variation of
  the slope is found at different spatial locations within the active
  region. We selected two regions that were not greatly affected by lower
  temperature emission along the line of sight. We found that the EM
  had a power law of the form EM ∝ T<SUP>b</SUP>, with b = 4.4 ± 0.4,
  and 4.6 ± 0.4, during the first and second appearance of the active
  region, respectively. During the second rotation, line-of-sight effects
  become more important, although difficult to estimate. We found that
  the use of the ground calibration for Hinode/EIS and the approximate
  method to derive the EM, used in previous publications, produce an
  underestimation of the slopes. The EM distribution in active region
  cores is generally found to be consistent with high frequency heating,
  and does not change much during the evolution of the active region.

Title: Emission Measure Distribution for Diffuse Regions in Solar
    Active Regions
Authors: Subramanian, Srividya; Tripathi, Durgesh; Klimchuk, James A.;
   Mason, Helen E.
Bibcode: 2014ApJ...795...76S
Altcode: 2014arXiv1409.1447S
  Our knowledge of the diffuse emission that encompasses active regions
  is very limited. In this paper we investigate two off-limb active
  regions, namely, AR 10939 and AR 10961, to probe the underlying heating
  mechanisms. For this purpose, we have used spectral observations from
  Hinode/EIS and employed the emission measure (EM) technique to obtain
  the thermal structure of these diffuse regions. Our results show that
  the characteristic EM distributions of the diffuse emission regions peak
  at log T = 6.25 and the coolward slopes are in the range 1.4-3.3. This
  suggests that both low- as well as high-frequency nanoflare heating
  events are at work. Our results provide additional constraints on the
  properties of these diffuse emission regions and their contribution to
  the background/foreground when active region cores are observed on-disk.

Title: Signatures of the non-Maxwellian κ-distributions in optically
    thin line spectra. I. Theory and synthetic Fe IX-XIII spectra
Authors: Dudík, J.; Del Zanna, G.; Mason, H. E.; Dzifčáková, E.
Bibcode: 2014A&A...570A.124D
Altcode: 2014arXiv1408.0950D
  <BR /> Aims: We investigate the possibility of diagnosing the degree of
  departure from the Maxwellian distribution using single-ion spectra
  originating in astrophysical plasmas in collisional ionization
  equilibrium. <BR /> Methods: New atomic data for excitation of Fe ix
  - Fe xiii are integrated under the assumption of a κ-distribution
  of electron energies. Diagnostic methods using lines of a single
  ion formed at any wavelength are explored. Such methods minimize
  uncertainties from the ionization and recombination rates, as well as
  the possible presence of non-equilibrium ionization. Approximations
  to the collision strengths are also investigated. <BR /> Results: The
  calculated intensities of most of the Fe ix - Fe xiii EUV lines show
  consistent behaviour with κ at constant temperature. Intensities
  of these lines decrease with κ, with the vast majority of ratios
  of strong lines showing little or no sensitivity to κ. Several of
  the line ratios, especially involving temperature-sensitive lines,
  show a sensitivity to κ that is of the order of several tens of per
  cent, or, in the case of Fe ix, up to a factor of two. Forbidden
  lines in the near-ultraviolet, visible, or infrared parts of the
  spectrum are an exception, with smaller intensity changes or even
  a reverse behaviour with κ. The most conspicuous example is the Fe
  x 6378.26 Å red line, whose intensity incerases with κ. This line
  is a potentially strong indicator of departures from the Maxwellian
  distribution. We find that it is possible to perform density diagnostics
  independently of κ, with many Fe xi, Fe xii, and Fe xiii line ratios
  showing strong density-sensitivity and negligible sensitivity to κ
  and temperature. We also tested different averaging of the collision
  strengths. It is found that averaging over 0.01 interval in log(E [ Ryd
  ]) is sufficient to produce accurate distribution-averaged collision
  strengths Υ(T,κ) at temperatures of the ion formation in ionization
  equilibrium. <P />Appendices are available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201424124/olm">http://www.aanda.org</A>

Title: Atomic data for astrophysics: Ni XV
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
Bibcode: 2014A&A...567A..18D
Altcode:
  We present the first R-matrix scattering calculation for electron
  collisional excitation of Ni xv. The large-scale target includes
  configurations up to n = 4. The calculations were carried out using
  the intermediate-coupling frame transformation method. Significant
  enhancements in the collision strengths, compared to previous
  distorted-wave (DW) calculations, are found for several cases,
  in particular the forbidden lines within the ground configuration
  and the 3s<SUP>2</SUP> 3p 4s levels. We provide a complete set
  of rates and a list of strongest lines that are observable in
  astrophysical plasmas. Previous identifications are reviewed, and
  a few new ones suggested. The new data can be used to accurately
  measure electron densities for high-temperature (3 MK) plasmas, and
  the nickel abundance. <P />The full dataset (energies, transition
  probabilities and rates) is available from our APAP website <A
  href="http://www.apap-network.org">http://www.apap-network.org</A>,
  and also at the CDS via anonymous ftp to <A
  href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
  (ftp://130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A18">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/567/A18</A>

Title: VizieR Online Data Catalog: Ni XV electron collisional
    excitation (Del Zanna+, 2014)
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
Bibcode: 2014yCat..35670018D
Altcode: 2014yCat..35679018D
  We present the first R-matrix scattering calculation for electron
  collisional excitation of NiXV. The large-scale target includes
  configurations up to n=4. The calculations were carried out using the
  intermediate-coupling frame transformation method (ICFT). Significant
  enhancements in the collision strengths, compared to previous
  distorted wave (DW) calculations, are found for several cases, in
  particular the forbidden lines within the ground configuration and
  the 3s<SUP>2</SUP> 3p 4s levels. We provide a complete set of rates
  and a list of strongest lines that are observable in astrophysical
  plasmas. Previous identifications are reviewed, and a few new ones
  suggested. The new data can be used to accurately measure electron
  densities for high-temperature (3MK) plasmas, and the nickel
  abundance. <P />(2 data files).

Title: Atomic data for astrophysics: Fe IX
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2014A&A...565A..77D
Altcode:
  We present the results of a new large-scale intermediate-coupling frame
  transformation R-matrix scattering calculation for electron collisional
  excitation of Fe ix. The target includes all the main configurations
  up to n = 5, to improve our earlier R-matrix and distorted-wave (DW)
  calculations for the n = 3,4 levels. Unlike similar calculations
  which we carried out for the other coronal iron ions, in this case the
  larger target does not significantly affect the collision strengths
  of the strongest transitions to the n = 3,4 levels. Some differences
  are however present for a few transitions, in particular for the 3d-4p
  line at 197.86 Å. For the weaker transitions, significant enhancements
  due to extra resonances resulting from this much bigger target are
  found. Several new line identifications are suggested. We find excellent
  agreement between predicted and observed line intensities in the EUV
  (Hinode EIS) showing that Fe ix lines provide a reliable temperature
  diagnostic. We also show that the visible forbidden lines are a good
  diagnostic to measure electron densities. <P />The full dataset
  (energies, transition probabilities and rates) are also available
  in electronic form at the APAP website (www.apap-network.org)
  and are only available at the CDS via anonymous ftp to <A
  href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
  (ftp://130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A77">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A77</A>

Title: Elemental abundances and temperatures of quiescent solar
    active region cores from X-ray observations
Authors: Del Zanna, G.; Mason, H. E.
Bibcode: 2014A&A...565A..14D
Altcode:
  A brief review of studies of elemental abundances and emission measures
  in quiescent solar active region cores is presented. Hinode EUV Imaging
  Spectrometer (EIS) observations of strong iron spectral lines have
  shown sharply peaked distributions around 3 MK. EIS observations of
  lines emitted by a range of elements have allowed good estimates of
  abundances relative to iron. However, X-ray observations are required
  to measure the plasma emission above 3 MK and the abundances of
  oxygen and neon. We revisit, using up-to-date atomic data, older
  X-ray observations obtained by a sounding rocket and by the Solar
  Maximum Mission (SMM) Flat Crystal Spectrometer (FCS). We find that
  the Fe/O and Fe/Ne ratios are normally increased by a factor of 3.2,
  compared to the photospheric values. Similar results are obtained
  from FCS observations of six quiescent active region cores. The FCS
  observations also indicate that the emission measure above 3 MK has
  a very steep negative slope, with very little plasma observed at 5
  MK or above. <P />Appendix A is available in electronic form at <A
  href="http://www.aanda.org/10.1051/0004-6361/201423471/olm">http://www.aanda.org</A>

Title: Slipping Magnetic Reconnection during an X-class Solar Flare
    Observed by SDO/AIA
Authors: Dudík, J.; Janvier, M.; Aulanier, G.; Del Zanna, G.;
   Karlický, M.; Mason, H. E.; Schmieder, B.
Bibcode: 2014ApJ...784..144D
Altcode: 2014arXiv1401.7529D
  We present SDO/AIA observations of an eruptive X-class flare of
  2012 July 12, and compare its evolution with the predictions of a
  three-dimensional (3D) numerical simulation. We focus on the dynamics of
  flare loops that are seen to undergo slipping reconnection during the
  flare. In the Atmospheric Imaging Assembly (AIA) 131 Å observations,
  lower parts of 10 MK flare loops exhibit an apparent motion with
  velocities of several tens of km s<SUP>-1</SUP> along the developing
  flare ribbons. In the early stages of the flare, flare ribbons consist
  of compact, localized bright transition-region emission from the
  footpoints of the flare loops. A differential emission measure analysis
  shows that the flare loops have temperatures up to the formation of
  Fe XXIV. A series of very long, S-shaped loops erupt, leading to a
  coronal mass ejection observed by STEREO. The observed dynamics are
  compared with the evolution of magnetic structures in the "standard
  solar flare model in 3D." This model matches the observations well,
  reproducing the apparently slipping flare loops, S-shaped erupting
  loops, and the evolution of flare ribbons. All of these processes are
  explained via 3D reconnection mechanisms resulting from the expansion
  of a torus-unstable flux rope. The AIA observations and the numerical
  model are complemented by radio observations showing a noise storm
  in the metric range. Dm-drifting pulsation structures occurring
  during the eruption indicate plasmoid ejection and enhancement of the
  reconnection rate. The bursty nature of radio emission shows that the
  slipping reconnection is still intermittent, although it is observed
  to persist for more than an hour.

Title: VizieR Online Data Catalog: Atomic data for FeIX (Del Zanna+,
    2014)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2014yCat..35650077D
Altcode: 2014yCat..35659077D
  We present the results of a new large-scale intermediate-coupling frame
  transformation R-matrix scattering calculation for electron collisional
  excitation of Fe IX. The target includes all the main configurations
  up to n=5, to improve our earlier R-matrix and distorted-wave (DW)
  calculations for the n=3,4 levels. Unlike similar calculations which
  we carried out for the other coronal iron ions, in this case the
  larger target does not significantly affect the collision strengths
  of the strongest transitions to the n=3,4 levels. Some differences
  are however present for a few transitions, in particular for the 3d-4p
  line at 197.86Å. For the weaker transitions, significant enhancements
  due to extra resonances resulting from this much bigger target are
  found. Several new line identifications are suggested. We find excellent
  agreement between predicted and observed line intensities in the EUV
  (Hinode EIS) showing that Fe IX lines provide a reliable temperature
  diagnostic. We also show that the visible forbidden lines are a good
  diagnostic to measure electron densities. <P />(2 data files).

Title: Diagnostics for the O IV and Si IV lines observed by IRIS
Authors: Dudik, Jaroslav; Mason, Helen; Del Zanna, Giulio; Golub,
   Leon; Dzifcakova, Elena
Bibcode: 2014cosp...40E.754D
Altcode:
  We investigate the formation of the IRIS O IV and Si IV lines under
  non-Maxwellian conditions characterized by kappa-distributions. It is
  found that the Si IV lines are always formed at lower temperatures
  than the O IV lines. However, as the departure from the Maxwellian
  increases, the peak formation temperatures are shifted progressively to
  lower and lower temperatures. Coupled with the slope of the differential
  emission measure (DEM), it is possible for the Si IV lines to be formed
  very close to the solar chromosphere, with the majority of the O IV
  intensities coming from a different, higher part of the transition
  region. The predicted spectra for kappa-distributions exhibit very low O
  IV intensities compared to Si IV, analogously to what is observed by the
  IRIS spacecraft. Potential density diagnostics are discussed, as well
  as the contribution of photoexcitation to the formation of these lines.

Title: Chromospheric evaporation in recurrent flares
Authors: Polito, V.; Mason, Helen; Del Zanna, Giulio; Dudik, Jaroslav
Bibcode: 2014cosp...40E2581P
Altcode:
  We present high-cadence (3 minutes) Hinode/EIS observations of small
  recurrent flares and provide densities and velocities of the upflowing
  plasma in the locations of the chromospheric evaporation. Lines formed
  in the 2-10 MK range have significant blueshifts, of the order of
  50 km/s or more. This upflowing plasma is the source of the 10 MK
  plasma that emits strongly in EUV and X-ray lines after the impulsive
  phases. We use the high-cadence and high-resolution SDO/AIA images
  to describe the locations of the upflows, and magnetograms to locate
  the ribbons. One interesting feature is that the recurrent flares are
  confined, until the last one when a large-scale eruption occurs.

Title: Response of Hinode XRT to quiet Sun, active region and
    flare plasma
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.
Bibcode: 2014A&A...561A..20O
Altcode:
  <BR /> Aims: We examine the response of the Hinode X-Ray
  Telescope (XRT), using simultaneous observations with the Hinode
  Extreme-ultraviolet Imaging Spectrometer (EIS), for a flare, an active
  region and a quiet Sun region. We also examine the relative intensity
  calibration of EIS and XRT. <BR /> Methods: EIS differential emission
  measure distribution (DEM) curves were used to create synthetic spectra
  with the CHIANTI atomic database. The contribution of spectral lines
  and continuum emission to each of the XRT channels was determined from
  the synthetic spectra, which were then convolved with the effective
  area of each XRT channel. The predicted total count rates for each
  channel were compared with the observed count rates. The effects
  of varying elemental abundances and the temperature range for the
  inversion were investigated. DEMs obtained from the XRT bands were
  also computed and compared to those obtained with EIS. <BR /> Results:
  For the active region observations, the observed XRT count rates for
  most of the channels are in reasonable agreement with those predicted
  using EIS observations, but are dependent on the elemental abundances
  chosen. Significant discrepancies between predicted and observed count
  rates were found and are discussed for the adjacent quiet Sun region
  and also for the flare. Synthetic spectra and continuum emission
  contributing to the XRT channels are presented and discussed for the
  active region, quiet Sun and flare observations.

Title: Solar Transition Region Lines Observed by the Interface Region
Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
Authors: Dudík, J.; Del Zanna, G.; Dzifčáková, E.; Mason, H. E.;
   Golub, L.
Bibcode: 2014ApJ...780L..12D
Altcode: 2013arXiv1311.6978D
  The formation of the transition region O IV and Si IV lines observable
  by the Interface Region Imaging Spectrograph (IRIS) is investigated
  for both Maxwellian and non-Maxwellian conditions characterized by
  a κ-distribution exhibiting a high-energy tail. The Si IV lines
  are formed at lower temperatures than the O IV lines for all κ. In
  non-Maxwellian situations with lower κ, the contribution functions
  are shifted to lower temperatures. Combined with the slope of the
  differential emission measure, it is possible for the Si IV lines to be
  formed at very different regions of the solar transition region than the
  O IV lines; possibly close to the solar chromosphere. Such situations
  might be discernible by IRIS. It is found that photoexcitation can be
  important for the Si IV lines, but is negligible for the O IV lines. The
  usefulness of the O IV ratios for density diagnostics independently of
  κ is investigated and it is found that the O IV 1404.78 Å/1399.77
  Å ratio provides a good density diagnostics except for very low T
  combined with extreme non-Maxwellian situations.

Title: A Collaborative FP7 Effort towards the First European
    Comprehensive SOLar Irradiance Data Exploitation (SOLID)
Authors: Haberreiter, Margit; Dasi, Maria; Delouille, Veronique; Del
   Zanna, Giulio; Dudok de Wit, Thierry; Ermolli, Ilaria; Kretzschmar,
   Matthieu; Krivova, Natalie; Mason, Helen; Qahwaji, Rami; Schmutz,
   Werner; Solanki, Sami; Thuillier, Gerard; Tourpali, Kleareti; Unruh,
   Yvonne; Verbeeck, Cis; Weber, Mark; Woods, Tom
Bibcode: 2013EGUGA..1513079H
Altcode:
  Variations of solar irradiance are the most important natural factor
  in the terrestrial climate and as such, the time dependent spectral
  solar irradiance is a crucial input to any climate modelling. There
  have been previous efforts to compile solar irradiance but it is
  still uncertain by how much the spectral and total solar irradiance
  changed on yearly, decadal and longer time scales. Observations of
  irradiance data exist in numerous disperse data sets. Therefore, it
  is important to bring together the European expertise in the field
  to analyse and merge the complete set of European irradiance data,
  complemented by archive data that include data from non-European
  missions. We report on the initiation of a collaborative effort to unify
  representatives from all European solar space experiments and European
  teams specialized in multi-wavelength solar image processing. It is
  intended to include the European groups involved in irradiance modelling
  and reconstruction. They will work with two different state of the art
  approaches to produce reconstructed spectral and total solar irradiance
  data as a function of time. These results will be used to bridge
  gaps in time and wavelength coverage of the observational data. This
  will allow the proposing SOLID team to reduce the uncertainties in
  the irradiance time series - an important requirement by the climate
  community - and to provide uniform data sets of modelled and observed
  solar irradiance data from the beginning of the space era to the
  present including proper error and uncertainty estimates. Climate
  research needs these data sets and therefore, the primary benefit
  is for the climate community, but the stellar community, planetary,
  lunar, and ionospheric researchers are also interested in having at
  their disposition incident radiation of the Sun. The proposing team
  plans to realize a wide international synergy in solar physics from
  7 European countries, and collaborators from the US, complemented by
  representatives from the climate community, who will accompany their
  research work with wide dissemination activities.

Title: Doppler Shifts in Active Region Moss Using SOHO/SUMER
Authors: Winebarger, Amy; Tripathi, Durgesh; Mason, Helen E.; Del
   Zanna, Giulio
Bibcode: 2013ApJ...767..107W
Altcode:
  The velocity of the plasma at the footpoint of hot loops in active
  region cores can be used to discriminate between different heating
  frequencies. Velocities on the order of a few kilometers per second
  would indicate low-frequency heating on sub-resolution strands,
  while velocities close to zero would indicate high-frequency (steady)
  heating. To discriminate between these two values requires accurate
  velocity measurements; previous velocity measurements suffer from
  large uncertainties, mainly due to the lack of an absolute wavelength
  reference scale. In this paper, we determine the velocity in the loop
  footpoints using observations from Solar Ultraviolet Measurements of
  Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We
  use neutral spectral lines to determine the wavelength scale of the
  observations with an uncertainty in the absolute velocity of &lt;3.5 km
  s<SUP>-1</SUP> and co-aligned Transition Region and Coronal Explorer
  (TRACE) images to identify footpoint regions. We studied three
  different active regions and found average redshifts in the Ne VIII
  770 Å emission line (formed at 6 × 10<SUP>5</SUP> K) of 5.17 ± 5.37
  km s<SUP>-1</SUP> and average redshifts in the C IV 1548 and 1550 Å
  emission lines (formed at 1 × 10<SUP>5</SUP> K) of 13.94 ± 4.93 km
  s<SUP>-1</SUP> and 14.91 ± 6.09 km s<SUP>-1</SUP>, respectively. We
  find no correlation between the brightness in the spectral line and
  the measured velocity, nor do we find correlation between the Ne VIII
  and C IV velocities measured co-spatially and co-temporally. SUMER
  scanned two of the active regions twice; in those active regions we
  find positive correlation between the co-spatial velocities measured
  during the first and second scans. These results provide definitive
  and quantitative measurements for comparisons with simulations of
  different coronal heating mechanisms.

Title: CHIANTI 7.1: a new database release for SDO data analysis
Authors: Young, P. R.; Landi, E.; Del Zanna, G.; Dere, K. P.; Mason,
   H. E.
Bibcode: 2013enss.confE..58Y
Altcode:
  Version 7.1 of the CHIANTI atomic database was released in October 2012
  and contains a number of improvements to better model data returned by
  the AIA and EVE instruments on board SDO. Specifically the models for
  the important iron ions Fe VIII to Fe XIV have been greatly expanded,
  yielding many thousands of new transitions in the 50-170 angstrom
  range that enable the irradiance spectra obtained by EVE to be modeled
  more accurately. A lack of available atomic data meant that the AIA 94
  angstrom channel was not well modeled at low temperatures in earlier
  versions of CHIANTI. New data for Fe VIII, Fe X and Fe XIV added to
  CHIANTI 7.1 give important contributions to the channel and greatly
  improve comparisons with theory.

Title: CHIANTI—An Atomic Database for Emission Lines. XIII. Soft
    X-Ray Improvements and Other Changes
Authors: Landi, E.; Young, P. R.; Dere, K. P.; Del Zanna, G.; Mason,
   H. E.
Bibcode: 2013ApJ...763...86L
Altcode:
  The CHIANTI spectral code consists of two parts: an atomic database
  and a suite of computer programs in Python and IDL. Together, they
  allow the calculation of the optically thin spectrum of astrophysical
  objects and provide spectroscopic plasma diagnostics for the analysis
  of astrophysical spectra. The database includes atomic energy levels,
  wavelengths, radiative transition probabilities, collision excitation
  rate coefficients, ionization, and recombination rate coefficients,
  as well as data to calculate free-free, free-bound, and two-photon
  continuum emission. Version 7.1 has been released, which includes
  improved data for several ions, recombination rates, and element
  abundances. In particular, it provides a large expansion of the
  CHIANTI models for key Fe ions from Fe VIII to Fe XIV to improve the
  predicted emission in the 50-170 Å wavelength range. All data and
  programs are freely available at http://www.chiantidatabase.org and
  in SolarSoft, while the Python interface to CHIANTI can be found at
  http://chiantipy.sourceforge.net.

Title: The Sun as a Star
Authors: Del Zanna, Giulio; Mason, Helen
Bibcode: 2013pss4.book...87D
Altcode:
  In this chapter we provide an overview of various observational and
  theoreticalaspects about the Sun, paying more attention to global ones,
  i.e., to thosewhere the Sun is considered as a star, so they can be
  more or less directlyrelated to those studied for other stars. The
  emphasis is on the processes bywhich energy is transferred to the
  solar atmosphere and then flows fromthe Sun in the form of radiation
  and particles. The chapter starts withan historical introduction,
  and then discusses various subjects, startingwith a brief description
  of the photosphere, the chromosphere, and thetransition region of
  the Sun. The interior of the Sun is then introduced,with the standard
  model and solar neutrinos, and with the observationsand theory of solar
  oscillations. We present some important results fromhelioseismology,
  and briefly discuss the problematics involved with theproduction and
  regeneration of the solar magnetic fields during a solarcycle.

Title: The spectroscopy of the dynamic Sun
Authors: Mason, Helen; Baker, Deb
Bibcode: 2012A&G....53f..29M
Altcode:
  MEETING REPORT Helen Mason and Deb Baker celebrate the collaboration
  between George Doschek and Tetsuya Watanabe that has uncovered so much
  about the Sun's behaviour.

Title: SDO AIA and EVE observations and modelling of solar flare loops
Authors: Petkaki, P.; Del Zanna, G.; Mason, H. E.; Bradshaw, S. J.
Bibcode: 2012A&A...547A..25P
Altcode:
  We present imaging and spectroscopic observations of an isolated
  C1-class solar flare, obtained with the Atmospheric Imaging Assembly
  (AIA) and Extreme ultraviolet Variability Experiment (EVE) on the Solar
  Dynamics Observatory (SDO). We obtain excellent agreement between the
  peak flare temperatures estimated using the EVE spectra with those
  obtained from GOES and, most importantly, from the ratio of the 94
  Å and 131 Å AIA channels, which are found to be dominated by Fe
  xviii and Fe xxi. These results confirm that these two AIA bands can
  be reliably used to provide temperature diagnostics for the peak and
  gradual phases of solar flares. The flare kernels, probable sources
  of chromospheric evaporation, are seen as strong localised emission
  in the AIA bands at the footpoints of flare loops. The flare loops
  are close to isothermal during the gradual phase. We have run several
  hydrodynamic simulations (using the HYDRAD code) to study the cooling
  of the flare loops. We find good overall agreement between observed and
  predicted electron temperatures and densities when a gradual increase
  and decrease of the heating is assumed.

Title: Atomic data for astrophysics: Fe xii soft X-ray lines
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2012A&A...543A.139D
Altcode:
  We present new large-scale R-matrix (up to n = 4) and distorted-wave
  (DW, up to n = 6) scattering calculations for electron collisional
  excitation of Fe xii. The first aim is to provide accurate atomic data
  for the soft X-rays, where strong decays from the n = 4 levels are
  present. As found in previous work on Fe x, resonances attached to n =
  4 levels increase the cross-sections for excitations from the ground
  state to some n = 4 levels, when compared to DW calculations. Cascading
  from higher levels is also important. We provide a number of models and
  line intensities, and list a number of strong unidentified lines. The
  second aim is to assess the effects of the large R-matrix calculation
  on the n = 3 transitions. Compared to our previous (n = 3) R-matrix
  calculation, we find overall excellent agreement to within a few
  percent, however a few key density diagnostic EUV intensities differ
  by about 60% at coronal densities. The new atomic data result in
  lower electron densities, resolving previous discrepancies with solar
  observations. <P />The full dataset (energies, transition probabilities
  and rates) are available in electronic form at our APAP website (<A
  href="http://www.apap-network.org">http://www.apap-network.org</A>)
  as well as at the CDS via anonymous ftp to
  cdsarc.u-strasbg.fr (130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A139">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/543/A139</A>

Title: Active Region Moss: Doppler Shifts from
    Hinode/Extreme-ultraviolet Imaging Spectrometer Observations
Authors: Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.
Bibcode: 2012ApJ...753...37T
Altcode: 2012arXiv1204.6550T
  Studying the Doppler shifts and the temperature dependence of Doppler
  shifts in moss regions can help us understand the heating processes
  in the core of the active regions. In this paper, we have used an
  active region observation recorded by the Extreme-ultraviolet Imaging
  Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the
  Doppler shifts in the moss regions. We have distinguished the moss
  regions from the rest of the active region by defining a low-density
  cutoff as derived by Tripathi et al. in 2010. We have carried out a
  very careful analysis of the EIS wavelength calibration based on the
  method described by Young et al. in 2012. For spectral lines having
  maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find
  that the velocity distribution peaks at around 0 km s<SUP>-1</SUP>
  with an estimated error of 4-5 km s<SUP>-1</SUP>. The width of the
  distribution decreases with temperature. The mean of the distribution
  shows a blueshift which increases with increasing temperature and the
  distribution also shows asymmetries toward blueshift. Comparing these
  results with observables predicted from different coronal heating
  models, we find that these results are consistent with both steady
  and impulsive heating scenarios. However, the fact that there are a
  significant number of pixels showing velocity amplitudes that exceed
  the uncertainty of 5 km s<SUP>-1</SUP> is suggestive of impulsive
  heating. Clearly, further observational constraints are needed to
  distinguish between these two heating scenarios.

Title: VizieR Online Data Catalog: Fe XII soft X-ray lines (Del
    Zanna+, 2012)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2012yCat..35430139D
Altcode: 2012yCat..35439139D
  We present new large-scale R-matrix (up to n=4) and distorted-wave (DW,
  up to n=6) scattering calculations for electron collisional excitation
  of Fe XII. The first aim is to provide accurate atomic data for the soft
  X-rays, where strong decays from the n=4 levels are present. As found
  in previous work on Fe X, resonances attached to n=4 levels increase the
  cross-sections for excitations from the ground state to some n=4 levels,
  when compared to DW calculations. Cascading from higher levels is also
  important. <P />We provide a number of models and line intensities,
  and list a number of strong unidentified lines. <P />The second aim
  is to assess the effects of the large R-matrix calculation on the n=3
  transitions. Compared to our previous (n=3) R-matrix calculation, we
  find overall excellent agreement to within a few percent, however a few
  key density diagnostic EUV intensities differ by about 60% at coronal
  densities. The new atomic data result in lower electron densities,
  resolving previous discrepancies with solar observations. <P />(5
  data files).

Title: Observations of Plasma Upflow in a Warm Loop with Hinode/EIS
Authors: Tripathi, Durgesh; Mason, Helen E.; Del Zanna, Giulio;
   Bradshaw, Steven
Bibcode: 2012ApJ...754L...4T
Altcode: 2012arXiv1206.3367T
  A complete understanding of Doppler shift in active region loops can
  help probe the basic physical mechanism involved into the heating
  of those loops. Here, we present observations of upflows in coronal
  loops detected in a range of temperatures (log T = 5.8-6.2). The loop
  was not discernible above these temperatures. The speed of upflow
  was strongest at the footpoint and decreased with height. The upflow
  speed at the footpoint was about 20 km s<SUP>-1</SUP> in Fe VIII, which
  decreased with temperature, being about 13 km s<SUP>-1</SUP> in Fe X,
  about 8 km s<SUP>-1</SUP> in Fe XII, and about 4 km s<SUP>-1</SUP> in
  Fe XIII. To the best of our knowledge, this is the first observation
  providing evidence of upflow of plasma in coronal loop structures at
  these temperatures. We interpret these observations as evidence of
  chromospheric evaporation in quasi-static coronal loops.

Title: VizieR Online Data Catalog: FeX soft X-ray lines (Del Zanna+,
    2012)
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2012yCat..35410090D
Altcode: 2012yCat..35419090D
  New atomic calculations for Fe X are presented. They focus on the need
  to model the soft X-ray spectrum and in particular the line at 94.0Å
  which is the dominant contribution to the Solar Dynamics Observatory
  (SDO) Atmospheric Imaging Assembly (AIA) 94Å band in quiet Sun
  conditions. This line, and others in the band, are due to strong
  decays from n=4 levels. We present new large-scale R-matrix (up to
  n=4) and distorted-wave (DW, up to n=6) scattering calculations for
  electron collisional excitation and compare them to earlier work. We
  find significant discrepancies with previous calculations. We show that
  resonances significantly increase the cross-sections for excitations
  from the ground state to some n=4 levels, in particular to those in
  the 3s<SUP>2</SUP> 3p<SUP>4</SUP> 4s configuration. Cascading from
  higher levels is also important. We suggest a new identification for
  the 3s 3p<SUP>6</SUP> <SUP>2</SUP>S<SUB>1/2</SUB> - 3s 3p<SUP>5</SUP>
  4s <SUP>2</SUP>P<SUB>3/2</SUB> transition, that has a predicted
  intensity larger than the decays from the 3s<SUP>2</SUP> 3p<SUP>4</SUP>
  4s levels which were identified by Edlen in 1936. The results presented
  here are relevant to our understanding of transitions from n=4 levels
  in a wide range of other ions. <P />(5 data files).

Title: Cross-Calibration of Hinode/EIS and SDO/AIA
Authors: O'Dwyer, B.; Zanna, G. D.; Mason, H. E.; Weber, M. A.;
   Tripathi, D.
Bibcode: 2012ASPC..455..369O
Altcode:
  We examine the contribution of spectral lines and continuum emission
  to the EUV channels of the Atmospheric Imaging Assembly (AIA) on
  the Solar Dynamics Observatory (SDO) in different regions of the
  solar atmosphere (coronal hole, quiet Sun, active region, and flare
  plasma). We highlight the contribution of particular spectral lines
  which under certain conditions can affect the interpretation of SDO
  AIA data. In addition we use simultaneous observations from the Hinode
  Extreme-ultraviolet Imaging Spectrometer (EIS) and SDO/AIA to examine
  their relative intensity calibration. Good agreement is found between
  the two instruments for an active region observation.

Title: Hinode Observations and Modeling of Small Flares
Authors: Zanna, G. D.; Mitra-Kraev, U.; Bradshaw, S. J.; Mason, H. E.;
   Asai, A.
Bibcode: 2012ASPC..455..295Z
Altcode:
  We present Hinode observations of a small B-class flare which occurred
  on May 22, 2007, supplemented with X-ray, EUV, and radio data. We
  found new signatures of chromospheric evaporation, strong (up to 170 km
  s<SUP>-1</SUP>) blue-shifted emission in lines formed around 2-3 MK,
  in a very narrow layer at the footpoints of a 10 MK flare loop. We
  have found good agreement between the observed properties and those
  predicted by a HYDRAD non-equilibrium hydrodynamic numerical simulation.

Title: Atomic data for astrophysics: Fe x soft X-ray lines
Authors: Del Zanna, G.; Storey, P. J.; Badnell, N. R.; Mason, H. E.
Bibcode: 2012A&A...541A..90D
Altcode:
  New atomic calculations for Fe x are presented. They focus on the need
  to model the soft X-ray spectrum and in particular the line at 94.0 Å
  which is the dominant contribution to the Solar Dynamics Observatory
  (SDO) Atmospheric Imaging Assembly (AIA) 94 Å band in quiet Sun
  conditions. This line, and others in the band, are due to strong decays
  from n = 4 levels. We present new large-scale R-matrix (up to n =
  4) and distorted-wave (DW, up to n = 6) scattering calculations for
  electron collisional excitation and compare them to earlier work. We
  find significant discrepancies with previous calculations. We show that
  resonances significantly increase the cross-sections for excitations
  from the ground state to some n = 4 levels, in particular to those
  in the 3s<SUP>2</SUP> 3p<SUP>4</SUP> 4s configuration. Cascading from
  higher levels is also important. We suggest a new identification for
  the 3s 3p<SUP>6</SUP><SUP>2</SUP>S<SUB>1/2</SUB>-3s 3p<SUP>5</SUP> 4s
  <SUP>2</SUP>P<SUB>3/2</SUB> transition, that has a predicted intensity
  larger than the decays from the 3s<SUP>2</SUP> 3p<SUP>4</SUP> 4s levels
  which were identified by Edlén in 1936. The results presented here
  are relevant to our understanding of transitions from n = 4 levels in a
  wide range of other ions. <P />The full dataset (energies, transition
  probabilities and rates) are available in electronic form at our APAP
  website (<A href="http://www.apap-network.org">www.apap-network.org</A>)
  as well as at the CDS via anonymous ftp to
  cdsarc.u-strasbg.fr (130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/A90">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/541/A90</A>

Title: Understanding Coronal Heating with Emission Measure
    Distributions
Authors: Klimchuk, James A.; Tripathi, D.; Bradshaw, S. J.; Mason,
   H. E.
Bibcode: 2012AAS...22042302K
Altcode:
  It is widely believed that the cross-field spatial scale of coronal
  heating is small, so that the fundamental plasma structures
  (loop strands) are spatially unresolved. We therefore must
  appeal to diagnostic techniques that are not strongly affected by
  spatial averaging. One valuable observable is the emission measure
  distribution, EM(T), which indicates how much material is present
  at each temperature. Using data from the Extreme-ultraviolet Imaging
  Spectrograph on the Hinode mission, we have determined emission measure
  distributions in the cores of two active regions. The distributions have
  power law slopes of approximately 2.4 coolward of the peak. We compare
  these slopes, as well as the amount of emission measure at very high
  temperature, with the predictions of a series of models. The models
  assume impulsive heating (nanoflares) in unresolved strands and take
  full account of nonequilibrium ionization.

Title: VizieR Online Data Catalog: Atomic data for X-ray lines of
    FeVIII and FeIX (O'Dwyer+, 2012)
Authors: O'Dwyer, B.; Del Zanna, G.; Badnell, N. R.; Mason, H. E.;
   Storey, P. J.
Bibcode: 2012yCat..35370022O
Altcode: 2012yCat..35379022O
  The distorted wave extension of the autostructure code has been used
  to calculate energy levels, radiative transition probabilities and
  collisional excitation rates of Fe VIII and Fe IX up to n=6 for Fe IX
  and n=7 for Fe VIII. We have compared some of the data with previous
  calculations, finding overall agreement for radiative transition
  rates, but interesting differences for some collisional data. <P
  />**************************************************************************
  * * * Sorry, but the author(s) never supplied the
  tabular material * * announced in the paper * * *
  **************************************************************************

Title: Spectroscopic Diagnostics and Heating of Active Region Cores
Authors: Tripathi, D.; Mason, H. E.; Klimchuk, J. A.
Bibcode: 2012decs.confE..92T
Altcode:
  It is widely believed that we are still far from spatially resolving
  the fundamental plasma structures in solar corona. Therefore,
  we must use spectroscopic diagnostic techniques such as emission
  measure distribution (EM(T)) and Doppler shifts that are not affected
  by spatial averaging. Using observations recorded by the Extreme
  ultraviolet Imaging Spectrometer we have studies emission measure (EM)
  distribution and Doppler shift in the moss and inter-moss regions. The
  EM distributions obtained for moss regions cab be reproduced by
  considering strong coronal condensation scenario suggesting bulk
  downflow of the plasma. Doppler shift measurements for the moss regions
  show that almost all the moss regions are red-shifted with velocities
  up to 15km/s with mean velocity of 5 km/s. However, the uncertainty
  on the Doppler shift was large. The EM distributions obtained for
  inter-moss regions have power law slopes of approximately 2.4 coolward
  of the peak. We compare the EM for inter-moss region with that obtained
  from nanoflare model using EBTEL (Enthalpy-Based Thermal Evolution of
  Loops). Our results suggest that the EM distribution for both the moss
  as well as inter-moss regions and Doppler shift in the moss regions can
  be explained by nanoflare heating. IRIS will provide a better account
  of the Doppler shift in the moss regions, which will dramatically
  enhance our understanding of the heating of active region core.

Title: Spectroscopic Diagnostics with IRIS
Authors: Mason, H. E.; Del Zanna, G.
Bibcode: 2012decs.confE..47M
Altcode:
  This talk will review the spectroscopic diagnostics available in the
  IRIS wavelength bands, built on the previous heritage of observations
  in the 1330-1410A wavelength band. Consideration will be given to the
  accuracy of available atomic data in CHIANTI and the relevant atomic
  processes. Ways in which the IRIS data could be used to complement
  observations from other observatories (SDO and Hinode) will be explored
  with a view to probing the energy transport and dissipation in the
  solar atmosphere.

Title: CHIANTI—An Atomic Database for Emission Lines. XII. Version
    7 of the Database
Authors: Landi, E.; Del Zanna, G.; Young, P. R.; Dere, K. P.; Mason,
   H. E.
Bibcode: 2012ApJ...744...99L
Altcode:
  The CHIANTI spectral code consists of an atomic database and
  a suite of computer programs to calculate the optically thin
  spectrum of astrophysical objects and carry out spectroscopic plasma
  diagnostics. The database includes atomic energy levels, wavelengths,
  radiative transition probabilities, collision excitation rate
  coefficients, and ionization and recombination rate coefficients,
  as well as data to calculate free-free, free-bound, and two-photon
  continuum emission. Version 7 has been released, which includes
  several new ions, significant updates to existing ions, as well as
  Chianti-Py, the implementation of CHIANTI software in the Python
  programming language. All data and programs are freely available at
  http://www.chiantidatabase.org, while the Python interface to CHIANTI
  can be found at http://chiantipy.sourceforge.net.

Title: Velocity Measurements for a Solar Active Region Fan Loop from
    Hinode/EIS Observations
Authors: Young, P. R.; O'Dwyer, B.; Mason, H. E.
Bibcode: 2012ApJ...744...14Y
Altcode: 2011arXiv1107.2362Y
  The velocity pattern of a fan loop structure within a solar active
  region over the temperature range 0.15-1.5 MK is derived using data from
  the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. The
  loop is aligned toward the observer's line of sight and shows downflows
  (redshifts) of around 15 km s<SUP>-1</SUP> up to a temperature of 0.8
  MK, but for temperatures of 1.0 MK and above the measured velocity
  shifts are consistent with no net flow. This velocity result applies
  over a projected spatial distance of 9 Mm and demonstrates that the
  cooler, redshifted plasma is physically disconnected from the hotter,
  stationary plasma. A scenario in which the fan loops consist of at
  least two groups of "strands"—one cooler and downflowing, the other
  hotter and stationary—is suggested. The cooler strands may represent
  a later evolutionary stage of the hotter strands. A density diagnostic
  of Mg VII was used to show that the electron density at around 0.8 MK
  falls from 3.2 × 10<SUP>9</SUP> cm<SUP>-3</SUP> at the loop base,
  to 5.0 × 10<SUP>8</SUP> cm<SUP>-3</SUP> at a projected height of
  15 Mm. A filling factor of 0.2 is found at temperatures close to the
  formation temperature of Mg VII (0.8 MK), confirming that the cooler,
  downflowing plasma occupies only a fraction of the apparent loop
  volume. The fan loop is rooted within a so-called outflow region that
  displays low intensity and blueshifts of up to 25 km s<SUP>-1</SUP> in
  Fe XII λ195.12 (formed at 1.5 MK), in contrast to the loop's redshifts
  of 15 km s<SUP>-1</SUP> at 0.8 MK. A new technique for obtaining an
  absolute wavelength calibration for the EIS instrument is presented and
  an instrumental effect, possibly related to a distorted point-spread
  function, that affects velocity measurements is identified.

Title: Atomic data for the X-ray lines of Fe viii and Fe ix
Authors: O'Dwyer, B.; Del Zanna, G.; Badnell, N. R.; Mason, H. E.;
   Storey, P. J.
Bibcode: 2012A&A...537A..22O
Altcode:
  The distorted wave extension of the autostructure code has been used
  to calculate energy levels, radiative transition probabilities and
  collisional excitation rates of Fe viii and Fe ix up to n = 6 for Fe ix
  and n = 7 for Fe viii. We have compared some of the data with previous
  calculations, finding overall agreement for radiative transition
  rates, but interesting differences for some collisional data. We have
  merged our data for the higher energy levels with published R-matrix
  collisional excitation rates for the lower ones to calculate spectral
  line intensities and compare them with observations. In particular,
  we have focused on the transitions from high energy levels of Fe
  viii &amp; Fe ix which are present in the 93-95 Å region. A few new
  identifications are tentatively provided. We find that Fe ix 5f-3d
  and Fe viii 7f-3d transitions only comprise a small fraction of
  the observed lines in the 93-95 Å region for quiet Sun conditions,
  and thus their contribution to the Solar Dynamics Observatory (SDO)
  Atmospheric Imaging Assembly (AIA) 94 Å band is expected to be
  small. <P />A complete list of calculated energies, radiative data
  and thermally averaged collision strengths is only available at the
  CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A22">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A22</A>

Title: Understanding Coronal Heating with Emission Measure
    Distributions
Authors: Klimchuk, J. A.; Tripathi, D.; Bradshaw, S. J.; Mason, H. E.
Bibcode: 2011AGUFMSH43F..03K
Altcode:
  It is widely believed that the cross-field spatial scale of coronal
  heating is small, so that the fundamental plasma structures
  (loop strands) are spatially unresolved. We therefore must
  appeal to diagnostic techniques that are not strongly affected by
  spatial averaging. One valuable observable is the emission measure
  distribution, EM(T), which indicates how much material is present
  at each temperature. Using data from the Extreme-ultraviolet Imaging
  Spectrograph on the Hinode mission, we have determined emission measure
  distributions in the cores of two active regions. The distributions
  have power law slopes of approximately 2.4 coolward of the peak. We
  compare these slopes, as well as the amount of emission measure at
  very high temperature, with the predictions of a series of models. The
  models assume impulsive heating (nanoflares) in unresolved strands and
  take full account of nonequilibrium ionization. A variety of nanoflare
  properties and initial conditions are considered. We also comment on the
  selection of spectral lines for upcoming missions like Solar Orbiter.

Title: SDO AIA and Hinode EIS observations of "warm" loops
Authors: Del Zanna, G.; O'Dwyer, B.; Mason, H. E.
Bibcode: 2011A&A...535A..46D
Altcode:
  We present simultaneous observations of active region "warm" (1 MK)
  loops using the Solar Dynamics Observatory (SDO) Atmospheric Imaging
  Assembly (AIA) and Hinode EUV Imaging Spectrometer (EIS). Sample EIS
  spectra for a loop footpoint and a lop leg region are presented, and are
  used to describe the spectral lines which contribute to the six AIA EUV
  channels, both directly and predicted with DEM modeling. We find good
  overall agreement between observed and predicted count rates for the 131
  Å, 193 Å, and 335 Å bands, but highlight a number of problems, partly
  to be ascribed to inter-calibration issues, partly due to the fact that
  a large number of lines remain unidentified for the 94 Å, 171 Å, and
  211 Å bands. We also found that the 335 Å band is severely affected by
  cross-talk with the 131 Å band and by second order contributions. We
  extend our previous work where we highlighted the multi-thermal nature
  of the SDO AIA bands to show that emission from lines formed at typical
  transition region temperatures (log T[K] = 5.0-5.8) can be significant
  for all the EUV channels, and even dominant in some cases. We also
  assess the possibility of deriving accurate emission measures from the
  AIA observations. We have found that the inversion of the AIA data to
  obtain a description of the thermal characteristics of warm loops is
  unreliable. We highlight the need for further work on the relevant
  atomic data before the AIA data can be reliably used for plasma
  diagnostic purposes. <P />Appendices A-C are available in electronic
  form at <A href="http://www.aanda.org">http://www.aanda.org</A>

Title: Emission Measure Distribution and Heating of Two Active
    Region Cores
Authors: Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.
Bibcode: 2011ApJ...740..111T
Altcode: 2011arXiv1107.4480T
  Using data from the Extreme-ultraviolet Imaging Spectrometer aboard
  Hinode, we have studied the coronal plasma in the core of two active
  regions. Concentrating on the area between opposite polarity moss, we
  found emission measure distributions having an approximate power-law
  form EMvpropT <SUP>2.4</SUP> from log T = 5.5 up to a peak at log T
  = 6.55. We show that the observations compare very favorably with
  a simple model of nanoflare-heated loop strands. They also appear
  to be consistent with more sophisticated nanoflare models. However,
  in the absence of additional constraints, steady heating is also a
  viable explanation.

Title: The 22 May 2007 B-class flare: new insights from Hinode
    observations
Authors: Del Zanna, G.; Mitra-Kraev, U.; Bradshaw, S. J.; Mason,
   H. E.; Asai, A.
Bibcode: 2011A&A...526A...1D
Altcode:
  We present multi-wavelength observations of a small B-class flare
  which occurred on the Sun on 2007 May 22. The observations include
  data from Hinode, GOES, TRACE and the Nobeyama Radioheliograph. We
  obtained spatially and spectrally-resolved information from the Hinode
  EUV Imaging Spectrometer (EIS) during this event. The temporal and
  temperature coverage of the EIS observations provides new insights into
  our understanding of chromospheric evaporation and cooling. The flare
  showed many “typical” features, such as brightenings in the ribbons,
  hot (10 MK) loop emission and subsequent cooling. We also observed
  a new feature, strong (up to 170 km s<SUP>-1</SUP>) blue-shifted
  emission in lines formed around 2-3 MK, located at the footpoints of
  the 10 MK coronal emission and within the ribbons. Electron densities
  at 2 MK in the kernels are high, of the order of 10<SUP>11</SUP>
  cm<SUP>-3</SUP>, suggesting a very narrow layer where the chromospheric
  evaporation occurs. We have run a non-equilibrium hydrodynamic numerical
  simulation using the HYDRAD code to study the cooling of the 10 MK
  plasma, finding good agreement between the predicted and observed
  temperatures, densities and ion populations. Line blending for some
  potentially useful diagnostic lines for flares, which are observed
  with Hinode/EIS, is also discussed.

Title: Hinode extreme-ultraviolet imaging spectrometer observations
    of a limb active region
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.; Sterling, A. C.;
   Tripathi, D.; Young, P. R.
Bibcode: 2011A&A...525A.137O
Altcode:
  <BR /> Aims: We investigate the electron density and temperature
  structure of a limb active region. <BR /> Methods: We have carried out
  a study of an active region close to the solar limb using observations
  from the Extreme-ultraviolet Imaging Spectrometer (EIS) and the X-ray
  telescope (XRT) on board Hinode. The electron density and temperature
  distributions of the coronal emission have been determined using
  emission line intensity ratios. Differential emission measure (DEM)
  analysis and the emission measure (EM) loci technique were used to
  examine the thermal structure of the emitting plasma as a function
  of distance from the limb. <BR /> Results: The highest temperature
  and electron density values are found to be located in the core of
  the active region, with a peak electron number density value of 1.9
  × 10<SUP>10</SUP> cm<SUP>-3</SUP> measured using the Fe XII 186.887
  Å to 192.394 Å line intensity ratio. The plasma along the line of
  sight in the active region was found to be multi-thermal at different
  distances from the limb. The EIS and XRT DEM analyses appear to be
  in agreement in the temperature interval from log T = 6.5-6.7. <BR />
  Conclusions: Our results provide new constraints for models of coronal
  heating in active regions.

Title: Science Objectives for an X-Ray Microcalorimeter Observing
    the Sun
Authors: Laming, J. Martin; Adams, J.; Alexander, D.; Aschwanden, M;
   Bailey, C.; Bandler, S.; Bookbinder, J.; Bradshaw, S.; Brickhouse,
   N.; Chervenak, J.; Christe, S.; Cirtain, J.; Cranmer, S.; Deiker, S.;
   DeLuca, E.; Del Zanna, G.; Dennis, B.; Doschek, G.; Eckart, M.; Fludra,
   A.; Finkbeiner, F.; Grigis, P.; Harrison, R.; Ji, L.; Kankelborg,
   C.; Kashyap, V.; Kelly, D.; Kelley, R.; Kilbourne, C.; Klimchuk, J.;
   Ko, Y. -K.; Landi, E.; Linton, M.; Longcope, D.; Lukin, V.; Mariska,
   J.; Martinez-Galarce, D.; Mason, H.; McKenzie, D.; Osten, R.; Peres,
   G.; Pevtsov, A.; Porter, K. Phillips F. S.; Rabin, D.; Rakowski, C.;
   Raymond, J.; Reale, F.; Reeves, K.; Sadleir, J.; Savin, D.; Schmelz,
   J.; Smith, R. K.; Smith, S.; Stern, R.; Sylwester, J.; Tripathi, D.;
   Ugarte-Urra, I.; Young, P.; Warren, H.; Wood, B.
Bibcode: 2010arXiv1011.4052L
Altcode:
  We present the science case for a broadband X-ray imager with
  high-resolution spectroscopy, including simulations of X-ray spectral
  diagnostics of both active regions and solar flares. This is part of
  a trilogy of white papers discussing science, instrument (Bandler et
  al. 2010), and missions (Bookbinder et al. 2010) to exploit major
  advances recently made in transition-edge sensor (TES) detector
  technology that enable resolution better than 2 eV in an array that
  can handle high count rates. Combined with a modest X-ray mirror, this
  instrument would combine arcsecondscale imaging with high-resolution
  spectra over a field of view sufficiently large for the study of
  active regions and flares, enabling a wide range of studies such as
  the detection of microheating in active regions, ion-resolved velocity
  flows, and the presence of non-thermal electrons in hot plasmas. It
  would also enable more direct comparisons between solar and stellar
  soft X-ray spectra, a waveband in which (unusually) we currently have
  much better stellar data than we do of the Sun.

Title: Evidence of Impulsive Heating in Active Region Core Loops
Authors: Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.
Bibcode: 2010ApJ...723..713T
Altcode: 2010arXiv1009.0663T
  Using a full spectral scan of an active region from the
  Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained emission
  measure EM(T) distributions in two different moss regions within the
  same active region. We have compared these with theoretical transition
  region EMs derived for three limiting cases, namely, static equilibrium,
  strong condensation, and strong evaporation from Klimchuk et al. The
  EM distributions in both the moss regions are strikingly similar and
  show a monotonically increasing trend from log T[K] = 5.15-6.3. Using
  photospheric abundances, we obtain a consistent EM distribution for
  all ions. Comparing the observed and theoretical EM distributions,
  we find that the observed EM distribution is best explained by the
  strong condensation case (EM<SUB>con</SUB>), suggesting that a downward
  enthalpy flux plays an important and possibly dominant role in powering
  the transition region moss emission. The downflows could be due to
  unresolved coronal plasma that is cooling and draining after having
  been impulsively heated. This supports the idea that the hot loops
  (with temperatures of 3-5 MK) seen in the core of active regions are
  heated by nanoflares.

Title: SDO/AIA response to coronal hole, quiet Sun, active region,
    and flare plasma
Authors: O'Dwyer, B.; Del Zanna, G.; Mason, H. E.; Weber, M. A.;
   Tripathi, D.
Bibcode: 2010A&A...521A..21O
Altcode:
  <BR /> Aims: We examine the contribution of spectral lines and continuum
  emission to the EUV channels of the Atmospheric Imaging Assembly (AIA)
  on the Solar Dynamics Observatory (SDO) in different regions of the
  solar atmosphere. <BR /> Methods: Synthetic spectra were obtained using
  the CHIANTI atomic database and sample differential emission measures
  for coronal hole, quiet Sun, active region and flare plasma. These
  synthetic spectra were convolved with the effective area of each
  channel, in order to determine the dominant contribution in different
  regions of the solar atmosphere. <BR /> Results: We highlight the
  contribution of particular spectral lines which under certain conditions
  can affect the interpretation of SDO/AIA data.

Title: Evidence for magnetic flux cancelation leading to an ejective
    solar eruption observed by Hinode, TRACE, STEREO, and SoHO/MDI
Authors: Sterling, A. C.; Chifor, C.; Mason, H. E.; Moore, R. L.;
   Young, P. R.
Bibcode: 2010A&A...521A..49S
Altcode:
  <BR /> Aims: We study the onset of a solar eruption involving a
  filament ejection on 2007 May 20. <BR /> Methods: We observe the
  filament in Hα images from Hinode/SOT and in EUV with TRACE and
  STEREO/SECCHI/EUVI. Hinode/XRT images are used to study the eruption in
  soft X-rays. From spectroscopic data taken with Hinode/EIS we obtain
  bulk-flow velocities, line profiles, and plasma densities in the
  onset region. The magnetic field evolution was observed in SoHO/MDI
  magnetograms. <BR /> Results: We observed a converging motion between
  two opposite polarity sunspots that form the primary magnetic polarity
  inversion line (PIL), along which resides filament material before
  eruption. Positive-flux magnetic elements, perhaps moving magnetic
  features (MMFs) flowing from the spot region, appear north of the
  spots, and the eruption onset occurs where these features cancel
  repeatedly in a negative-polarity region north of the sunspots. An
  ejection of material observed in Hα and EUV marks the start of the
  filament eruption (its “fast-rise”). The start of the ejection is
  accompanied by a sudden brightening across the PIL at the jet's base,
  observed in both broad-band images and in EIS. Small-scale transient
  brightenings covering a wide temperature range (Log T<SUB>e</SUB> =
  4.8-6.3) are also observed in the onset region prior to eruption. The
  preflare transient brightenings are characterized by sudden, localized
  density enhancements (to above Log n<SUB>e</SUB> [ cm<SUP>-3</SUP>] =
  9.75, in Fe XIII) that appear along the PIL during a time when pre-flare
  brightenings were occurring. The measured densities in the eruption
  onset region outside the times of those enhancements decrease with
  temperature. Persistent downflows (red-shifts) and line-broadening
  (Fe XII) are present along the PIL. <BR /> Conclusions: The array of
  observations is consistent with the pre-eruption sheared-core magnetic
  field being gradually destabilized by evolutionary tether-cutting flux
  cancelation that was driven by converging photospheric flows, and the
  main filament ejection being triggered by flux cancelation between the
  positive flux elements and the surrounding negative field. A definitive
  statement however on the eruption's ultimate cause would require
  comparison with simulations, or additional detailed observations of
  other eruptions occurring in similar magnetic circumstances. <P />The
  video that accompanies Fig. 3 is only available in electronic form at
  <A href="http://www.aanda.org">http://www.aanda.org</A>

Title: Active region moss. Basic physical parameters and their
    temporal variation
Authors: Tripathi, D.; Mason, H. E.; Del Zanna, G.; Young, P. R.
Bibcode: 2010A&A...518A..42T
Altcode: 2010arXiv1005.2220T
  Context. Active region moss are transition region phenomena, first noted
  in the images recorded by the Transition Region and Coronal Explorer
  (TRACE) in λ171. Moss regions are thought to be the footpoints of
  hot loops (3-5 MK) seen in the core of active regions. These hot
  loops appear “fuzzy” (unresolved). Therefore, it is difficult to
  study the physical plasma parameters in individual hot core loops and
  hence their heating mechanisms. Moss regions provide an excellent
  opportunity to study the physics of hot loops. In addition, they
  allow us to study the transition region dynamics in the footpoint
  regions. <BR /> Aims: To derive the physical plasma parameters such as
  temperature, electron density, and filling factors in moss regions and
  to study their variation over a short (an hour) and a long time period
  (5 consecutive days). <BR /> Methods: Primarily, we have analyzed
  spectroscopic observations recorded by the Extreme-ultraviolet Imaging
  Spectrometer (EIS) aboard Hinode. In addition we have used supplementary
  observations taken from TRACE and the X-Ray Telescope (XRT) aboard
  Hinode. <BR /> Results: The moss emission is strongest in the Fe XII
  and Fe XIII lines. Based on analyses using line ratios and emission
  measure we found that moss regions have a characteristic temperature
  of log T[K] = 6.2. The temperature structure in moss region remains
  almost identical from one region to another and it does not change
  with time. The electron densities measured at different locations in
  the moss regions using Fe XII ratios are about 1-3 × 10<SUP>10</SUP>
  cm<SUP>-3</SUP> and about 2-4 × 10<SUP>9</SUP> cm<SUP>-3</SUP> using
  Fe XIII and Fe XIV. The densities in the moss regions are similar in
  different places and show very little variation over short and long
  time scales. The derived electron density substantially increased (by
  a factor of about 3-4 or even more in some cases) when a background
  subtraction was performed. The filling factor of the moss plasma
  can vary between 0.1-1 and the path length along which the emission
  originates is from a few 100 to a few 1000 kms long. By combining the
  observations recorded by TRACE, EIS and XRT, we find that the moss
  regions correspond to the footpoints of both hot and warm loops.

Title: VizieR Online Data Catalog: IRON project. LXVIII (Del Zanna+,
    2010)
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
Bibcode: 2010yCat..35140040D
Altcode: 2010yCat..35149040D
  **************************************************************************
  * * * Sorry, but the author(s) never supplied the tabular
  material * * (detailed tables) as announced in the paper. *
  **************************************************************************

Title: Plasma Flows in Coronal Loops
Authors: Young, Peter R.; Dwyer, B. O.; Mason, H. E.
Bibcode: 2010AAS...21630004Y
Altcode:
  A survey of plasma flows in coronal loops is underway using data from
  the Hinode/EIS instrument. The principal target is a study of flows
  in 1 MK (so-called 'warm' loops). Using emission lines formed between
  logT=5.6 and 6.2 it is possible to study the temperature dependence of
  the flows, and also the density of the emitting material. The results
  will be critical to making a definitive statement about whether apparent
  motions seen in TRACE 171 movies are due to actual mass motion or wave
  propagation. In addition we will also comment on the relation between
  the flows in warm loops and those in the newly-discovered active region
  outflow regions found by Hinode.

Title: Atomic data from the IRON project. LXVIII. Electron impact
    excitation of Fe xi
Authors: Del Zanna, G.; Storey, P. J.; Mason, H. E.
Bibcode: 2010A&A...514A..40D
Altcode:
  A new R-matrix scattering calculation for electron collisional
  excitation of Fe xi is presented and compared to earlier
  calculations. The calculation includes 145 LS terms and 465
  fine-structure levels and uses the intermediate-coupling frame
  transformation method (ICFT). We discuss the strong interactions that
  exist between three J = 1 levels in the 3s<SUP>2</SUP> 3p<SUP>3</SUP>
  3d electron configuration. These levels give rise to strong lines
  in the EUV spectrum and their energies and identifications have
  been the source of much confusion in the literature. We show that
  the oscillator and collision strengths linking these levels to
  the ground levels of the ion are very sensitive to the choice of
  configuration basis and argue that most earlier calculations have
  failed to represent these levels adequately. <P />Detailed tables
  of the present data are available in electronic form at the CDS
  via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via <A
  href="http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A40">http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/514/A40</A>

Title: VizieR Online Data Catalog: IRON Project. LVIII. (Storey+,
    2005)
Authors: Storey, P. J.; Del Zanna, G.; Mason, H. E.; Zeippen, C. J.
Bibcode: 2010yCat..34330717S
Altcode:
  A new calculation of rate coefficients for electron collisional
  excitation of Fe XII is presented and compared to earlier
  calculations. Significant differences are found with all earlier work
  due to the inclusion of resonance processes that have not previously
  been considered and to the use of the intermediate coupling frame
  transformation method. The resulting dataset of collision strengths
  is shown to resolve many of the outstanding discrepancies between
  theory and solar observations. In particular, density sensitive
  line ratios in Fe XII now indicate electron densities close to
  those derived from other ions of comparable ionization potential. <P
  />**************************************************************************
  * * * Sorry, but the author(s) never supplied the
  tabular material * * announced in the paper * * *
  **************************************************************************

Title: Two types of magnetic flux cancelation in the solar eruption
    of 2007 May 20
Authors: Sterling, Alphonse; Moore, Ronald; Mason, Helen
Bibcode: 2010cosp...38.1946S
Altcode: 2010cosp.meet.1946S
  We study a solar eruption on 2007 May 20, in an effort to understand the
  cWe study a solar eruption of 2007 May 20, in an effort to understand
  the cause of the eruption's onset. The event produced a GOES class
  B6.7 flare peaking at 05:56 UT, while ejecting a surge/filament and
  producing a coronal mass ejection (CME). We examine several data
  sets, including Hα images from the Solar Optical Telescope (SOT) on
  Hinode, EUV images from TRACE, and line-of-sight magnetograms from
  SoHO/MDI. Flux cancelation occurs among two different sets of flux
  elements inside of the erupting active region: First, for several days
  prior to eruption, opposite-polarity sunspot groups inside the region
  move toward each other, leading to the cancelation of ∼ 1021 Mx
  of flux over three days. Second, within hours prior to the eruption,
  positive-polarity moving magnetic features (MMFs) flowing out of the
  positive-flux spots at ∼ 1 km/s repeatedly cancel with field inside
  a patch of negative-polarity flux located north of the sunspots. The
  filament erupts as a surge whose base is rooted in the location where
  the MMF cancelation occurs, while during the eruption that filament
  flows out along the polarity inversion line between the converging spot
  groups. We conclude that a plausible scenario is that the converging
  spot fields brought the magnetic region to the brink of instability,
  and the MMF cancelation pushed the system "over the edge," triggering
  the eruption. This work was funded by NASA's Science Mission Directorate
  thought the Living With a Star Targeted Research and Technology Program,
  the Supporting Research and Program, and the Hinode project.

Title: Diagnostics of Active Region Loops Observed with Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Dwivedi, B. N.; Del Zanna, G.
Bibcode: 2009ASPC..415..260T
Altcode:
  The Extreme Ultraviolet Imaging Spectrometer (EIS) on board Hinode
  provides us with an excellent opportunity to study the physical
  parameters in spatially resolved coronal structures. In this paper
  we have carried out a study of active region loops using observations
  from the EIS. The active region was observed on 2007 Ma 19 using the
  1 arcsec slit of EIS. At coronal temperatures, we find that electron
  densities measured from Fe XII and Si X line ratios decrease along
  the loop length, being ≈10<SUP>10</SUP>0 cm<SUP>-3</SUP> at foot
  point and ≈10<SUP>8.5</SUP> cm<SUP>-3</SUP> at a height of about 75
  Mm. However, the electron densities measured from the Mg VII line ratios
  (at a transition region temperature) show significantly lower values
  at the foot point. The electron temperature along the loop increases
  with height from ≈0.8 MK (at foot point) to ≈1.5 MK (at a height
  of 75 Mm). The temperature diagnostics using EM-loci at different
  locations along the loop show that the loop is ``nearly isothermal''
  or ``mildly multi-thermal'' along the LOS. These measurements provide
  important constraints on the theoretical modelling of coronal loops.

Title: Multi-Instrument Campaigns to Observe the Off-Limb Corona
Authors: Del Zanna, G.; Andretta, V.; Poletto, G.; Teriaca, L.; Ko,
   Y. -K.; Mason, H. E.; Vourdilas, A.; Bemporad, A.; Magri, M.
Bibcode: 2009ASPC..415..315D
Altcode:
  We briefly describe two multi-instrument campaigns we coordinated to
  observe the off-limb corona in 2007, with some preliminary results. The
  first one (Hinode HOP 7) was a SOHO/Hinode/TRACE/STEREO/Ulysses
  week-long campaign during the SOHO-Ulysses quadrature in 2007 May. We
  could not achieve all of our goals, however we were very fortunate in
  that the ``Del Zanna'' active region appeared on the Sun at the right
  longitude, and that a filament eruption and a CME were observed. Of
  particular significance is the finding of large (100 km s<SUP>-1</SUP>)
  non-thermal broadenings in all coronal lines observed by Hinode/EIS
  in the region where the filament was erupting. The second campaign
  (Hinode HOP 44) involved SOHO (CDS, SUMER, UVCS), Hinode, and TRACE to
  measure the physical parameters of plume/interplume regions in the polar
  coronal holes from the low corona to 1.7 solar radii, on 30/10-4/11. We
  obtained a good set of observations, however various instrumental
  constraints and the lack of fully developed plumes limited our goals.

Title: Temperature Tomography of a Coronal Sigmoid Supporting the
    Gradual Formation of a Flux Rope
Authors: Tripathi, Durgesh; Kliem, Bernhard; Mason, Helen E.; Young,
   Peter R.; Green, Lucie M.
Bibcode: 2009ApJ...698L..27T
Altcode: 2009arXiv0904.4782T
  Multiwavelength observations of a sigmoidal (S-shaped) solar coronal
  source by the EUV Imaging Spectrometer and the X-Ray Telescope
  aboard the Hinode spacecraft and by the EUV Imager aboard STEREO are
  reported. The data reveal the coexistence of a pair of J-shaped hot
  arcs at temperatures T&gt;2 MK with an S-shaped structure at somewhat
  lower temperatures (T ≈ 1-1.3 MK). The middle section of the S-shaped
  structure runs along the polarity inversion line of the photospheric
  field, bridging the gap between the arcs. Flux cancellation occurs
  at the same location in the photosphere. The sigmoid forms in the
  gradual decay phase of the active region, which does not experience
  an eruption. These findings correspond to the expected signatures
  of a flux rope forming, or being augmented, gradually by a topology
  transformation inside a magnetic arcade. In such a transformation, the
  plasma on newly formed helical field lines in the outer flux shell of
  the rope (S-shaped in projection) is expected to enter a cooling phase
  once the reconnection of their parent field line pairs (double-J shaped
  in projection) is complete. Thus, the data support the conjecture that
  flux ropes can exist in the corona prior to eruptive activity.

Title: CHIANTI - an atomic database for emission lines. IX. Ionization
    rates, recombination rates, ionization equilibria for the elements
    hydrogen through zinc and updated atomic data
Authors: Dere, K. P.; Landi, E.; Young, P. R.; Del Zanna, G.; Landini,
   M.; Mason, H. E.
Bibcode: 2009A&A...498..915D
Altcode:
  Aims: The goal of the CHIANTI atomic database is to provide a set of
  atomic data for the interpretation of astrophysical spectra emitted by
  collisionally dominated, high temperature, optically thin sources. <BR
  />Methods: A complete set of ground level ionization and recombination
  rate coefficients has been assembled for all atoms and ions of the
  elements of H through Zn and inserted into the latest version of the
  CHIANTI database, CHIANTI 6. Ionization rate coefficients are taken from
  the recent work of Dere (2007, A&amp;A, 466, 771) and recombination
  rates from a variety of sources in the literature. These new rate
  coefficients have allowed the calculation of a new set of ionization
  equilibria and radiative loss rate coefficients. For some ions, such
  as Fe VIII and Fe IX, there are significant differences from previous
  calculations. In addition, existing atomic parameters have been revised
  and new atomic parameters inserted into the database. <BR />Results:
  For each ion in the CHIANTI database, elemental abundances, ionization
  potentials, atomic energy levels, radiative rates, electron and proton
  collisional rate coefficients, ionization and recombination rate
  coefficients, and collisional ionization equilibrium populations are
  provided. In addition, parameters for the calculation of the continuum
  due to bremsstrahlung, radiative recombination and two-photon decay are
  provided. A suite of programs written in the Interactive Data Language
  (IDL) are available to calculate line and continuum emissivities
  and other properties. All data and programs are freely available at
  http://wwwsolar.nrl.navy.mil/chianti

Title: CHIANTI Version 6.0 - Inclusion of Ionization and Recombination
    Rates
Authors: Dere, Kenneth P.; Landi, E.; Young, P.; Del Zanna, G.; Mason,
   H.; Landini, M.
Bibcode: 2009SPD....40.1504D
Altcode:
  A new version of the CHIANTI atomic database for astrophysical
  spectroscopy is being prepared for imminent release. This will
  constitute Version 6.0. The main focus of this release is the inclusion
  of ionization cross-sections and rate coefficients from Dere (2007)
  and recombination rate coefficients from the literature, in particular,
  the calculations of Badnell and colleagues. A new set of ionization
  equilibria have been calculated from these rate coefficients. These
  show some significant differences from previous calculations. Atomic
  data for many ions have been revised and new calculations are included
  that enable the calculation of spectra of ions new to the CHIANTI
  database. The radiative loss function has been calculated based on
  the CHIANTI Version 6 database for both coronal and photospheric
  abundances. <P />A paper describing CHIANTI Version 6.0 in detail has
  been accepted for publication in Astronomy and Astrophysics.

Title: Active Region Loops: Hinode/Extreme-Ultraviolet Imaging
    Spectrometer Observations
Authors: Tripathi, Durgesh; Mason, Helen E.; Dwivedi, Bhola N.;
   del Zanna, Giulio; Young, Peter R.
Bibcode: 2009ApJ...694.1256T
Altcode: 2009arXiv0901.0095T
  We have carried out a study of active region loops using observations
  from the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode
  using 1'' raster data for an active region observed on 2007 May 19. We
  find that active region structures which are clearly discernible in
  cooler lines (≈1 MK) become "fuzzy" at higher temperatures (≈2
  MK). The active region was comprised of redshifted emissions (downflows)
  in the core and blueshifted emissions (upflows) at the boundary. The
  flow velocities estimated in the two regions located near the footpoints
  of coronal loop showed redshifted emission at transition region
  temperature and blueshifted emission at coronal temperature. The upflow
  speed in these regions increased with temperature. For more detailed
  study we selected one particular well-defined loop. Downward flows are
  detected along the coronal loop, being stronger in lower-temperature
  lines (rising up to 60 km s<SUP>-1</SUP> near the footpoint). The
  downflow was localized toward the footpoint in transition region lines
  (Si VII) and toward the loop top in high-temperature line (Fe XV). By
  carefully accounting for the background emission we found that the
  loop structure was close to isothermal for each position along the
  loop, with the temperature rising from around 0.8 MK to 1.5 MK from
  the close to the base to higher up toward the apex (≈75 Mm). We
  derived electron density using well-established line ratio diagnostic
  techniques. Electron densities along the active region loop were found
  to vary from 10<SUP>10</SUP> cm<SUP>-3</SUP> close to the footpoint to
  10<SUP>8.5</SUP> cm<SUP>-3</SUP> higher up. A lower electron density,
  varying from 10<SUP>9</SUP> cm<SUP>-3</SUP> close to the footpoint to
  10<SUP>8.5</SUP> cm<SUP>-3</SUP> higher up, was found for the lower
  temperature density diagnostic. Using these densities we derived filling
  factors in along the coronal loop which can be as low as 0.02 near the
  base of the loop. The filling factor increased with projected height
  of the loop. These results provide important constraints on coronal
  loop modeling.

Title: Partially-erupting prominences: a comparison between
    observations and model-predicted observables
Authors: Tripathi, D.; Gibson, S. E.; Qiu, J.; Fletcher, L.; Liu,
   R.; Gilbert, H.; Mason, H. E.
Bibcode: 2009A&A...498..295T
Altcode: 2009arXiv0902.1228T
  Aims: We investigate several partially-erupting prominences to
  study their relationship with other CME-associated phenomena and
  compare these observations with observables predicted by a model
  of partially-expelled-flux-ropes (Gibson &amp; Fan 2006a, ApJ,
  637, L65; 2006b, J. Geophys. Res., 111, 12103). <BR />Methods: We
  studied 6 selected events with partially-erupting prominences using
  multi-wavelength observations recorded by the Extreme-ultraviolet
  Imaging Telescope (EIT), Transition Region and Coronal Explorer
  (TRACE), Mauna Loa Solar Observatory (MLSO), Big Bear Solar Observatory
  (BBSO), and Soft X-ray Telescope (SXT). The observational features
  associated with partially-erupting prominences were then compared
  with the predicted observables from the model. <BR />Results: The
  partially-expelled-flux-rope (PEFR) model can explain the partial
  eruption of these prominences, and in addition predicts a variety
  of other CME-related observables that provide evidence of internal
  reconnection during eruption. We find that all of the partially-erupting
  prominences studied in this paper exhibit indirect evidence of internal
  reconnection. Moreover, all cases showed evidence of at least one
  observable unique to the PEFR model, e.g., dimmings external to the
  source region and/or a soft X-ray cusp overlying a reformed sigmoid. <BR
  />Conclusions: The PEFR model provides a plausible mechanism to explain
  the observed evolution of partially-erupting-prominence-associated
  CMEs in our study.

Title: Are Coronal Loops Isothermal or Multithermal?
Authors: Schmelz, J. T.; Nasraoui, K.; Rightmire, L. A.; Kimble,
   J. A.; del Zanna, G.; Cirtain, J. W.; DeLuca, E. E.; Mason, H. E.
Bibcode: 2009ApJ...691..503S
Altcode: 2009arXiv0901.3281S
  Surprisingly few solar coronal loops have been observed simultaneously
  with TRACE and SOHO/Coronal Diagnostics Spectrometer (CDS), and even
  fewer analyses of these loops have been conducted and published. The
  SOHO Joint Observing Program 146 was designed in part to provide the
  simultaneous observations required for in-depth temperature analysis of
  active region loops and determine whether these loops are isothermal
  or multithermal. The data analyzed in this paper were taken on 2003
  January 17 of AR 10250. We used TRACE filter ratios, emission measure
  loci, and two methods of differential emission measure analysis to
  examine the temperature structure of three different loops. TRACE and
  CDS observations agree that Loop 1 is isothermal with log T = 5.85,
  both along the line of sight as well as along the length of the loop
  leg that is visible in the CDS field of view. Loop 2 is hotter than
  Loop 1. It is multithermal along the line of sight, with significant
  emission between 6.2 &lt; log T&lt; 6.4, but the loop apex region
  is out of the CDS field of view so it is not possible to determine
  the temperature distribution as a function of the loop height. Loop
  3 also appears to be multithermal, but a blended loop that is just
  barely resolved with CDS may be adding cool emission to the Loop
  3 intensities and complicating our results. So, are coronal loops
  isothermal or multithermal? The answer appears to be yes.

Title: Magnetic flux cancellation associated with a recurring solar
    jet observed with Hinode, RHESSI, and STEREO/EUVI
Authors: Chifor, C.; Isobe, H.; Mason, H. E.; Hannah, I. G.; Young,
   P. R.; Del Zanna, G.; Krucker, S.; Ichimoto, K.; Katsukawa, Y.;
   Yokoyama, T.
Bibcode: 2008A&A...491..279C
Altcode:
  Aims: We study the physical properties of a recurring solar active
  region jet observed in X-rays and extreme-ultraviolet (EUV). <BR
  />Methods: Multi-wavelength data from all three instruments on
  board Hinode were analysed. X-ray imaging and spectroscopy of the
  microflaring emission associated with the jets was performed with the
  Reuven Ramaty High Energy Spectroscopic Imager (RHESSI). Associated
  EUV jets were observed with the Sun Earth Connection Coronal and
  Heliospheric Investigation (SECCHI)/Extreme Ultraviolet Imager
  (EUVI) on board STEREO. <BR />Results: We found a correlation between
  recurring magnetic flux cancellation close to a pore, the X-ray jet
  emission, and associated Ca II H ribbon brightenings. We estimated the
  lower limit for the decrease in magnetic energy associated with the
  X-ray jet emission at 3 × 10<SUP>29</SUP> erg. The recurring plasma
  ejection was observed simultaneously at EUV and X-ray temperatures,
  associated with type III radio bursts and microflaring activity at the
  jet footpoint. <BR />Conclusions: The recurring jet (EUV and X-ray)
  emissions can be attributed to chromospheric evaporation flows due to
  recurring coronal magnetic reconnection. In this process, the estimated
  minimum loss in the magnetic energy is sufficient to account for the
  total energy required to launch the jet. <P />Movie of Fig. 3 is only
  available in electronic form via http://www.aanda.org

Title: Chapter 7: Active Region Diagnostics
Authors: Mason, H. E.; Tripathi, D.
Bibcode: 2008psa..book..127M
Altcode:
  Active regions present us with complex and dynamic structures, which
  look relatively simple, but are in fact very difficult to model and
  explain. An active region is a region on the Sun where the magnetic
  field breaks through the surface (photosphere and chromosphere) to
  form giant arches of hot plasma. The magnetic field is stronger than
  in surrounding regions and the plasma is hotter, so emits strongly
  in UV and X-ray radiation. Figures 7.1 and 7.2 show UV images of the
  Sun taken with the Transition Region and Coronal Explorer (TRACE)
  spacecraft and the Extreme Ultraviolet Imaging Telescope (EIT) aboard
  the Solar and Heliospheric Observatory (SOHO) spacecraft. The hot plasma
  (around a million degree) traces out the magnetic field structures...

Title: Active Region Microflares From Hinode and RHESSI
Authors: Chifor, C.; Hannah, I. G.; Mason, H. E.; Isobe, H.; Yokoyama,
   T.; Young, P. R.; Tripathi, D.
Bibcode: 2008ASPC..397..164C
Altcode:
  We are studying microflares (A, B-C class flares) in active regions
  using coordinated observations from Hinode and RHESSI. Hinode/EIS
  has unprecedented diagnostic power for small, transient activity
  in the solar corona, providing temperature, density, and velocity
  information. For this purpose, we designed and ran an EIS observing
  sequence to provide high-cadence data at both transition region and
  coronal temperatures. A preliminary analysis of these observations is
  reported, with one data set given as an example.

Title: Source Region Evolution of the Solar Wind Disappearance Event
    of 11 May 1999
Authors: Janardhan, P.; Tripathi, D.; Mason, H. E.
Bibcode: 2008ESPM...122.118J
Altcode:
  A recent, detailed study of the well known "solar wind disappearance
  event" of 11 May 1999 traced its origin to a coronal hole lying adjacent
  to a large active region, AR8525 <P />in Carrington rotation 1949. The
  active region was located at central meridian on 05 May 1999 when the
  flows responsible for this event began. In this paper we examine the
  evolution of the active region-coronal hole complex during 5-6 May 1999
  to study the changes that apparently played a key role in causing this
  disappearance event. To study the evolution of the solar source region
  of the disappearance event of 11 May 1999 we have used images from the
  Soft X-ray Telescope (SXT), the Extreme-ultraviolet Imaging Telescope
  (EIT) and the Michelson Doppler Imager (MDI) to examine the evolution
  of the coronal hole and active region complex at the source region of
  the disappearance event. We find a dynamic evolution taking place in
  the coronal hole-active region boundary at the source region of the
  disappearance event of 11 May 1999. Based on the combined observations
  it appears that the rapid evolution seen in the coronal hole is due to
  reconnection's taking place between the newly emerging flux and the open
  field regions from the coronal hole and the active region-coronal hole
  boundary regions. This evolution, which is found to reduce the area of
  the coronal hole, is accompanied by the formation of new loops in EUV
  images which are spatially and temporally correlated with emerging flux
  regions as seen in MDI data. <P />As opposed to the well known drivers
  of space weather phenomena like CME's or large flares, disappearance
  events are not associated with explosive solar phenomena. However, they
  do produce other observable effects that are not fully understood. In
  the period leading up to the disappearance event of 11 May 1999, our
  observations, during quiet solar conditions and in the absence of CMEs,
  provide the first clear evidence for Sun-Earth connection originating
  from an evolving active region-coronal hole region located at central
  meridian. With the exception of corotating interacting regions, these
  observations provide the first link between the Sun and space weather
  effects at 1 AU, arising from non-explosive solar events.

Title: Density Structure in Active Regions from Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.; Chifor, C.; Del
   Zanna, G.
Bibcode: 2008ASPC..397...45T
Altcode:
  The Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode
  provides an excellent opportunity to study the physical plasma
  parameters in spatially resolved coronal features. In this paper we
  present the density structure in an active region at many different
  temperatures. The active region was rastered on May 01, 2007 with the
  2^{''} slit. We find that the electron density is highest in the core
  of the active region where it exceeds log_{10} N_e = 10.5.

Title: Nonthermal and thermal diagnostics of a solar flare observed
    with RESIK and RHESSI
Authors: Dzifčáková, E.; Kulinová, A.; Chifor, C.; Mason, H. E.;
   Del Zanna, G.; Sylwester, J.; Sylwester, B.
Bibcode: 2008A&A...488..311D
Altcode:
  Aims: We aim to prove and diagnose the occurrence of nonthermal
  electron distributions in solar flare plasma using X-ray spectral
  observations. <BR />Methods: An M4.9 flare on 2003 January 7/8 was
  observed with the RESIK instrument in the 3-6 Å wavelength range (2-4
  keV) and with RHESSI at energies above 6 keV. The temporal behavior
  of RESIK flare spectra has been analyzed for two different types of
  velocity distributions - a thermal (Maxwellian) distribution and a
  nonthermal plasma distribution of free electrons. The Si XIV, Si XIII,
  and Si XIId satellite lines observed with RESIK in the 5-6 Å range
  were used to determine the degree of deviation from Maxwellian, and
  the equivalent non-Maxwellian pseudo-temperature, τ. The diagnostics
  presented are sensitive to the shape of the distribution in the energy
  range where the maximum of the electron distribution occurs (where
  the bulk of electrons reside) and does not include the influence
  of the shape of the high-energy tail of the distribution. Under
  the assumption of a Maxwellian distribution of electron velocities,
  the plasma temperature was determined from an emission measure (EM)
  loci analysis and a differential emission measure (DEM) analysis of
  RESIK spectra. The high-energy end of the flare radiative emission
  was investigated through RHESSI spectral analysis. <BR />Results:
  The nonthermal analysis of RESIK spectra has shown that the largest
  deviations of the plasma electron distribution from Maxwellian appeared
  during the impulsive phase of the flare. The decay phase spectra had
  an almost isothermal character. The pseudo-temperature, τ, reached
  its maximum around the peak time of the soft and hard X-ray fluxes. The
  temporal behavior of the temperatures derived from the thermal analysis
  was similar to the behavior of the nonthermal pseudo-temperature. The
  values of the pseudo-temperature were consistent with the temperatures
  obtained in both thermal analyses, but lower than the temperatures
  derived from the slope of the RHESSI continua. In comparison with the
  synthetic isothermal or multithermal spectra, the nonthermal synthetic
  spectra fitted the observed Si XIId satellite lines much more closely
  (the error is less than 10%). The fluxes in the Si XIId satellite lines
  in isothermal or multithermal spectra have been underestimated by a
  factor of three or more in comparison to the observed fluxes. The
  value of this factor varies with time and it is different for the
  different satellite lines. <BR />Conclusions: Evidence was found for
  considerable deviations of the distribution of free electrons from
  Maxwellian in the plasma during a solar flare. These occurred mainly
  during the flare impulsive phase and can be diagnosed using existing
  X-ray spectral observations.

Title: The solar wind disappearance event of 11 May 1999: source
    region evolution
Authors: Janardhan, P.; Tripathi, D.; Mason, H. E.
Bibcode: 2008A&A...488L...1J
Altcode: 2008arXiv0807.2697J
  Context: A recent, detailed study of the well-known “solar wind
  disappearance event” of 11 May 1999 traced its origin to a coronal
  hole (CH) lying adjacent to a large active region (AR), AR8525 in
  Carrington rotation 1949. The AR was located at central meridian on 05
  May 1999 when the flows responsible for this event began. We examine
  the evolution of the AR-CH complex during 5-6 May 1999 to study the
  changes that apparently played a key role in causing this disappearance
  event. <BR />Aims: To study the evolution of the solar source region
  of the disappearance event of 11 May 1999. <BR />Methods: Using images
  from the Soft X-ray Telescope (SXT), the Extreme-ultraviolet Imaging
  Telescope (EIT) and the Michelson Doppler Imager (MDI) to examine
  the evolution of the CH and AR complex at the source region of the
  disappearance event. <BR />Results: We find a dynamic evolution taking
  place in the CH-AR boundary at the source region of the disappearance
  event of 11 May 1999. This evolution, which is found to reduce the
  area of the CH, is accompanied by the formation of new loops in EUV
  images that are spatially-and-temporally correlated with emerging flux
  regions as seen in MDI data. <BR />Conclusions: In the period leading
  up to the disappearance event of 11 May 1999, our observations,
  during quiet solar conditions and in the absence of CMEs, provide
  the first clear evidence for Sun-Earth connection originating from an
  evolving AR-CH region located at central meridian. With the exception
  of corotating interacting regions (CIR), these observations provide the
  first link between the Sun and space weather effects at 1 AU, arising
  from non-explosive solar events. <P />2 movies are only available in
  electronic form at http://www.aanda.org

Title: Magnetic Flux Cancelation Leading to the Eruption of a Coronal
Mass Ejection: Observations from Hinode, SOHO, TRACE, and STEREO
Authors: Sterling, A. C.; Chifor, C.; Mason, H.; Moore, R. L.
Bibcode: 2008AGUSMSP23B..05S
Altcode:
  We study a solar eruption involving ejection of a filament on 2007 May
  20, using instruments on Hinode, STEREO, TRACE, and SOHO. We observe
  the filament in EUV from TRACE and STEREO, and in H-alpha from SOT on
  Hinode. We also see the eruption in soft X-rays with XRT on Hinode,
  and in several EUV lines from EIS on Hinode. SOHO/MDI magnetograms
  show that converging motion between opposite-polarity sunspots in the
  region result in expansion of large-scale loops overlying the region's
  primary magnetic neutral line, along which sits filament material prior
  to its eruption. The source location of an EUV filament's surge-like
  ejection is a negative-polarity magnetic region that is north of the
  interacting spots, and patches of magnetic field flow at ~ 0.5 km/s
  from the positive converging spots into the negative region in the
  north. Apparently, repeated episodes of flux cancelation occur where
  the flowing positive flux collides with the northern negative flux,
  and the source of the EUV filament's ejection is near this cancelation
  site. Spectroscopic data from EIS are available for a portion of the
  active region that includes the northern cancelation site, and from
  these data we obtain bulk-flow velocities, line-broadening turbulent
  velocities, and densities of plasma in the region. The array of
  observations is consistent with the pre-eruption sheared-core magnetic
  arcade being gradually destabilized by evolutionary tether-cutting
  flux cancelation that was driven by converging photospheric flows.

Title: Density structure of an active region and associated moss
    using Hinode/EIS
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.; Del Zanna, G.
Bibcode: 2008A&A...481L..53T
Altcode: 2008arXiv0802.3311T
  Context: Studying the problem of active region heating requires precise
  measurements of physical plasma parameters such as electron density,
  temperature, etc. It is also important to understand the relationship
  of coronal structures with the magnetic field. The Extreme-ultraviolet
  Imaging Spectrometer (EIS) aboard Hinode provides a rare opportunity to
  derive electron density simultaneously at different temperatures. <BR
  />Aims: We study the density structure and characterise plasma in
  active regions and associated moss regions. In addition, we study its
  relationship to the photospheric magnetic field. <BR />Methods: We used
  data recorded by the EIS, together with magnetic field measurements
  from the Michelson Doppler Imager (MDI) aboard SoHO and images recorded
  with the Transition Region And Coronal Explorer (TRACE) and X-Ray
  Telescope (XRT/Hinode). <BR />Results: We find that the hot core of
  the active region is densest with values as high as 10<SUP>10.5</SUP>
  cm<SUP>-3</SUP>. The electron density estimated in specific regions
  in the active region moss decreases with increasing temperature. The
  moss areas were located primarily on one side of the active region,
  and they map the positive polarity regions almost exactly. The density
  within the moss region was highest at log T=5.8{-}6.1, with a value
  around 10<SUP>10.0{-</SUP>10.5} cm<SUP>-3</SUP>. The moss densities
  were highest in the strong positive magnetic field region. However,
  there was no such correlation for the negative polarity areas, where
  there was a large sunspot.

Title: An active region jet observed with Hinode
Authors: Chifor, C.; Young, P. R.; Isobe, H.; Mason, H. E.; Tripathi,
   D.; Hara, H.; Yokoyama, T.
Bibcode: 2008A&A...481L..57C
Altcode:
  Aims:We study the physical properties of an active region (AR) jet in
  order to probe the mechanisms responsible for it. <BR />Methods: We
  report 2007 January 15/16 observations of a recurring jet situated on
  the west side of NOAA AR 10938. Multi-wavelength data from all three
  instruments onboard Hinode were analysed. This paper focuses on one
  instance of a jet observed with the Hinode/EUV Imaging Spectrometer
  (EIS). Using EIS raster data we measured the temperatures, Doppler
  shifts, density, and filling factor. <BR />Results: A strong
  blue-shifted component and an indication of a weak red-shifted
  component at the base of the jet was observed around Log T<SUB>e</SUB>
  = 6.2. The up-flow velocities exceeded 150 km s<SUP>-1</SUP>. The
  jet component was seen over a range of temperatures between 5.4 and
  6.4 in Log T_e. Using Fe XII λ186 and λ195 line ratios, we measured
  densities above Log N<SUB>e</SUB> = 11 for the high-velocity up-flow
  component. We found that the density of the high-velocity up-flow
  increases with velocity. We estimate the filling factor in the jet
  up-flow to be &lt;0.03. With the Hinode/Solar Optical Telescope (SOT),
  we observed recurrent (quasi periodic) magnetic flux cancelations just
  before the recurrent jet emission was seen in images taken with the
  X-ray Telescope (XRT). <BR />Conclusions: The high-velocity up-flows,
  together with the density dependence on velocity, support an evaporation
  scenario for the acceleration of this jet. The high density and small
  filling factor, coupled with the high Doppler velocities are strongly
  suggestive of multiple small-scale magnetic reconnection events being
  responsible for the production of both EUV and X-ray jets.

Title: Computation of Non-Maxwellian Electron Excitation Rates for
Ions of Astrophysical Interest: Fe XV - A Test Case
Authors: Dzifčáková, Elena; Mason, Helen
Bibcode: 2008SoPh..247..301D
Altcode: 2008SoPh..tmp...14D
  Dzifčáková previously developed a method for calculating the
  influence of nonthermal electron-velocity distributions on the
  intensities of spectral lines (Solar Phys.234, 243, 2006; In: Lacoste,
  H., Ouwehand, L. (eds.) SOHO-17. 10 Years of SOHO and Beyond, SP-617,
  ESA, Noordwijk, 89, 2006). Here, we study this method in detail for
  the test case: Fe XV. It involves fitting a parametric form to the
  electron-excitation data in the CHIANTI atomic database. We assess
  the reliability of these fits by comparing them with the source atomic
  data, both Upsilons (Maxwellian-averaged collision strengths) and the
  original collision strengths. An accuracy for the method of better than
  15% is deduced for all transitions, with a much higher accuracy than
  this for the strong electric-dipole transitions. A κ-distribution,
  which has an increased number of electrons in the high-energy tail
  of the distribution, is considered as an example. The shape of the
  κ-distribution affects the electron-excitation rate and thus the
  relative intensities of the spectral lines. Since the shape of the
  electron distribution function also influences the ionization balance of
  Fe, both effects change the final intensities of the lines. Synthetic
  spectra for Fe XV and Fe XVI in the wavelength range 50 - 80 Å are
  presented for a κ-distribution and compared with solar observations.

Title: Solar Transition Region Features Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Doschek,
   George A.; Culhane, Len; Hara, Hirohisa
Bibcode: 2007PASJ...59S.727Y
Altcode: 2007arXiv0706.1856Y
  Two types of solar active region feature prominent at transition region
  temperatures are identified in Hinode/EIS data of AR 10938 taken on
  2007 January 20. The footpoints of 1 MK TRACE loops are shown to emit
  strongly in emission lines formed at log T = 5.4-5.8, allowing the
  temperature increase along the footpoints to be clearly seen. A density
  diagnostic of Mg VII yields the density in the footpoints, with one
  loop showing a decrease from 3 × 10<SUP>9</SUP> cm<SUP>-3</SUP> at the
  base to 1.5 × 10<SUP>9</SUP> cm<SUP>-3</SUP> at a projected height
  of 20 Mm. The second feature is a compact active region transition
  region brightening which is particularly intense in O V emission
  (log T = 5.4) but also has a signature at temperatures up to log T =
  6.3. The Mg VII diagnostic gives a density of 4 × 10<SUP>10</SUP>
  cm<SUP>-3</SUP>, and emission lines of Mg VI and Mg VII show line
  profiles broadened by 50kms<SUP>-1</SUP> and wings extending beyond
  ± 200kms<SUP>-1</SUP>. Continuum emission in the short wavelength
  band is also found to be enhanced, and is suggested to be free-bound
  emission from recombination onto He<SUP>+</SUP>.

Title: The Temperature and Density Structure of an Active Region
    Observed with the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Authors: Doschek, George A.; Mariska, John T.; Warren, Harry P.;
   Culhane, Len; Watanabe, Tetsuya; Young, Peter R.; Mason, Helen E.;
   Dere, Kenneth P.
Bibcode: 2007PASJ...59S.707D
Altcode:
  The Extreme-Ultraviolet Imaging Spectrometer (EIS) on Hinode
  produces high resolution spectra that can be combined via rasters
  into monochromatic images of solar structures, such as active
  regions. Electron temperature and density maps of the structures can
  be obtained by imaging the structures in different spectral lines with
  ratios sensitive to either temperature or density. Doppler maps and
  ion temperature maps can be made from spectral line wavelengths and
  profiles, respectively. In this paper we discuss coronal temperature
  and density distributions within an active region, illustrating the
  power of EIS for solar plasma diagnostics.

Title: EUV Emission Lines and Diagnostics Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Dere,
   Ken P.; Landi, Enrico; Landini, Massimo; Doschek, George A.; Brown,
   Charles M.; Culhane, Len; Harra, Louise K.; Watanabe, Tetsuya; Hara,
   Hirohisa
Bibcode: 2007PASJ...59S.857Y
Altcode: 2007arXiv0706.1857Y
  Quiet Sun and active region spectra from the Hinode/EIS instrument are
  presented, and the strongest lines from different temperature regions
  discussed. A list of emission lines recommended to be included in EIS
  observation studies is presented based on analysis of blending and
  diagnostic potential using the CHIANTI atomic database. In addition
  we identify the most useful density diagnostics from the ions covered
  by EIS.

Title: Application of CHIANTI to Solar-B
Authors: Dere, K.; Landi, E.; Del Zanna, G.; Young, P.; Mason, H.;
   Landini, M.
Bibcode: 2007ASPC..369...35D
Altcode:
  CHIANTI (http://wwwsolar.nrl.navy.mil/chianti.html) has been developed
  to support the interpretation of solar and astrophysical spectroscopic
  measurements. The most recent release, version 5.0 (Landi et al. 2005)
  presents an improvement over previous versions by including new
  large scale datasets for Fe ions from Fe XVII to Fe XXIV for X-ray
  emission and improved atomic data for EUV line emission. We will
  demonstrate how this can be applied to the analysis of XRT and EIS
  data, in particular. For example, new excitation rates for Fe XII have
  resolved a long standing problem in the use of Fe XII line ratios as
  accurate density diagnostics. Current work involves improvements to
  ionization and recombination rates which will also be useful in the
  interpretation of Solar-B data

Title: Nonthermal Velocities in Solar Active Regions Observed with
    the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Authors: Doschek, G. A.; Mariska, J. T.; Warren, H. P.; Brown, C. M.;
   Culhane, J. L.; Hara, H.; Watanabe, T.; Young, P. R.; Mason, H. E.
Bibcode: 2007ApJ...667L.109D
Altcode:
  We discuss nonthermal velocities in an active region as revealed
  by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode
  spacecraft. The velocities are derived from spectral line profiles in
  the extreme-ultraviolet (EUV) from a strong line of Fe XII at 195.12 Å
  by fitting each line profile to a Gaussian function. We compare maps
  of the full width at half-maximum values, the Fe XII spectral line
  intensity, the Fe XII Doppler shift, the electron temperature, and
  electron density. We find that the largest widths in the active region
  do not occur in the most intense regions, but seem to concentrate in
  less intense regions, some of which are directly adjacent to coronal
  loops, and some of which concentrate in regions which also exhibit
  relative Doppler outflows. The increased widths can also occur over
  extended parts of the active region.

Title: A bright coronal downflow seen in multi-wavelength
observations: evidence of a bifurcating flux-rope?
Authors: Tripathi, D.; Solanki, S. K.; Mason, H. E.; Webb, D. F.
Bibcode: 2007A&A...472..633T
Altcode: 2008arXiv0802.3616T
  Aims:We study the origin and characteristics of a bright coronal
  downflow seen after a coronal mass ejection associated with
  erupting prominences on 5 March 2000. <BR />Methods: This study
  extends that of Tripathi et al. (2006b, A&amp;A, 449, 369) based
  on the Extreme-ultraviolet Imaging Telescope (EIT), the Soft X-ray
  Telescope (SXT) and the Large Angle Spectrometric Coronagraph (LASCO)
  observations. We combined those results with an analysis of the
  observations taken by the Hα and the Mk4 coronagraphs at the Mauna Loa
  Solar Observatory (MLSO). The combined data-set spans a broad range of
  temperature as well as continuous observations from the solar surface
  out to 30 R<SUB>⊙</SUB>. <BR />Results: The downflow started at
  around 1.6 R<SUB>⊙</SUB> and contained both hot and cold gas. The
  downflow was observed in the Hα and the Mk4 coronagraphs as well as
  the EIT and the SXT and was approximately co-spatial and co-temporal
  providing evidence of multi-thermal plasma. The Hα and Mk4 images
  show cusp-shaped structures close to the location where the downflow
  started. Mk4 observations reveal that the speed of the downflow in
  the early phase was substantially higher than the free-fall speed,
  implying a strong downward acceleration near the height at which
  the downflow started. <BR />Conclusions: The origin of the downflow
  was likely to have been magnetic reconnection taking place inside
  the erupting flux rope that led to its bifurcation. <P />Movies are
  available in electronic form at http://www.aanda.org

Title: X-ray precursors to flares and filament eruptions
Authors: Chifor, C.; Tripathi, D.; Mason, H. E.; Dennis, B. R.
Bibcode: 2007A&A...472..967C
Altcode:
  Aims:To study preflare X-ray brightenings as diagnostics of the
  destabilisation of flare-associated erupting filaments/prominences. <BR
  />Methods: We combine new observations from the Transition Region
  and Coronal Explorer (TRACE) and the Reuven Ramaty High Energy Solar
  Spectroscopic Imager (RHESSI), as well as revisit events reported in the
  literature to date, in order to scrutinise the preflare activity during
  eight flare-associated filament eruptions. <BR />Results: The preflare
  activity occurs in the form of discrete, localised X-ray brightenings
  observed between 2 and 50 min before the impulsive phase of the flare
  and filament acceleration. These transient preflare brightenings are
  situated on or near (within 10{ arcsec} of) the polarity inversion
  line (PIL), coincident with emerging and/or canceling magnetic
  flux. The filaments begin to rise from the location of the preflare
  brightenings. In five out of eight events, the preflare brightenings
  were observed beneath the filament channel, close to the filament
  footpoint first observed to rise. Both thermal and nonthermal hard
  X-ray emissions during the preflare enhancement were detected with
  RHESSI, suggesting that both plasma heating and electron acceleration
  occurred at this time. The main energy release during the impulsive
  phase of the flare is observed close to (within 50{ arcsec} of) the
  preflare brightenings. The fast-rise phase of the filament eruption
  starts at the same time as the onset of the main flare or up to 5 min
  later. <BR />Conclusions: The preflare brightenings are precursors to
  the flare and filament eruption. These precursors represent distinct,
  localised instances of energy release, rather than a gradual energy
  release prior to the main flare. The X-ray precursors represent clearly
  observable signatures in the early stages of the eruption. Together with
  the timing of the filament fast-rise at or after the main flare onset,
  the X-ray precursors provide evidence for a tether-cutting mechanism
  initially manifested as localised magnetic reconnection being a common
  trigger for both flare emission and filament eruption. <P />Movies and
  Appendix A are only available in electronic form at http://www.aanda.org

Title: Coronal Loops: Isothermal or Multithermal?
Authors: Kimble, Jason; Schmelz, J. T.; Nasraoui, K.; Cirtain, J. W.;
   Del Zanna, G.; DeLuca, E. E.; Mason, H. E.
Bibcode: 2007AAS...210.9120K
Altcode: 2007BAAS...39..207K
  The coronal loop data used for this analysis were taken on 2003 January
  17 at 14:24:45 UT by the Coronal Diagnostic Spectrometer (CDS) aboard
  the Solar and Heliospheric Observatory. We use the Chianti atomic
  physics data base and the hybrid coronal abundances to determine
  temperatures and densities for positions along several loops. The
  traditional method used to create our differential emission measure
  (DEM) curves has been forward folding, but we are now using both
  emission measure loci plots and DEM automatic inversion to support
  and confirm the original conclusions. In this poster, we will look
  specifically at the emission measure loci analysis of three loops
  visible in the CDS data set. We find different results for each of
  these loops. One of the loops seems to be composed of isothermal
  plasma with Log T = 5.8 MK. The temperature does not appear to change
  with position, from the footpoint to the loop leg. Unfortunately,
  the loop top is outside the CDS field of view. Each pixel examined in
  the second loop seems to require a multithermal DEM distribution. For
  the third loop, the temperature increases and the density appears
  to decrease with loop height, reminiscent of traditional hydrostatic
  loop models. Solar physics research at the University of Memphis is
  supported by NSF ATM-0402729 and NASA NNG05GE68G.

Title: SOHO-CDS: Thermal and Density Analysis of Coronal Loops
Authors: Rightmire, Lisa; Schmelz, J. T.; Cirtain, J. W.; Del Zanna,
   G.; DeLuca, E. E.; Mason, H. E.
Bibcode: 2007AAS...210.9121R
Altcode: 2007BAAS...39..207R
  Data was obtained using the Coronal Diagnostic Spectrometer (CDS)
  instrument on the Solar and Heliospheric Observatory (SOHO). The goal
  of this project is to analyze the data obtained by the CDS instrument
  in order to determine the behavior of temperature and density of the
  coronal loop progressing from the foot point and moving up the loop. The
  loop being analyzed was observed by CDS on 2003 January 17 and the foot
  point was located at solar coordinates (585,-472) arcsecs. A background
  pixel and several pixels on the loop were selected. The background pixel
  intensity was then subtracted from each loop pixel intensity in order to
  isolate the emission from each loop pixel. The spectral line intensities
  of each loop pixel were analyzed to determine which spectral lines
  had any significant contribution to the loop intensity. The predicted
  and observed intensities of these significant lines were then used to
  create a differential emission measure (DEM) curve to best fit each
  loop pixel emission. Comparison of the DEM curves for each loop pixel
  indicates that the temperature increases and the density decreases,
  while progressing up the loop. Solar physics research at the University
  of Memphis is supported by NSF ATM-0402729 and NASA NNG05GE68G.

Title: Are Coronal Loops Isothermal Or Multithermal? Yes!
Authors: Schmelz, Joan T.; Nasraoui, K.; Rightmire, L.; Garst, J.;
   Kimble, J.; Cirtain, J.; DeLuca, E. E.; Del Zanna, G.; Mason, H.
Bibcode: 2007AAS...210.9431S
Altcode: 2007BAAS...39..222S
  Analysis of loops observed with the Coronal Diagnostics Spectrometer
  (CDS) and the Transition Region and Coronal Explorer (TRACE) reveal
  examples of both isothermal and multithermal plasma. These data
  were taken on 2003 January 17, and since the loops are on the disk,
  a lot of work was done on the details of background subtraction. The
  background-subtracted CDS intensities were analyzed using three
  methods: (1) Emission Measure Loci, (2) Forward-Folding DEM, and (3)
  Automatic-Inversion DEM. The first loop appears to be isothermal,
  with Log T = 5.8 MK. The forward-folding DEM shows a spike at this
  temperature and the EM Loci curves all intersect at this point. The
  automatic-inversion DEM results are broadened, however, as a result
  of the smoothing required for this method. This loop has a uniform
  temperature along the segment visible in the CDS field of view,
  and this result is confirmed using the TRACE data. The pixels along
  the second loop do not appear to be isothermal. The EM Loci curves
  do not intersect at a single point and both DEM methods show a broad
  curve. Other loops in this data set as well as loop evolution will be
  investigated if time permits. Solar physics research at the University
  of Memphis is supported by NSF ATM-0402729 and NASA NNG05GE68G.

Title: Differential Emission Measurements on Sparse Raster Data
    from SOHO-CDS
Authors: Garst, Jennifer W.; Schmelz, J. T.; Nasraoui, K.; Cirtain,
   J. W.; DeLuca, E. E.; Del Zanna, G.; Mason, H. E.
Bibcode: 2007AAS...210.2517G
Altcode: 2007BAAS...39..133G
  Two types of rasters were taken on 2003 January 17 with the Solar and
  Heliospheric Observatory’s Coronal Diagnostic Spectrometer. The
  first type contains a continuous image of coronal loops under
  investigation while the second, the ‘sparse raster,’ was taken at
  spatial intervals in order to simulate enhanced time resolution. With
  this technique, intensities in 14 passbands were collected at fixed
  positions on the solar disk every 7 minutes. The start time for the
  CDS observations was 06:51:27 UT and the observing sequences ran for
  7 hours. The continuous rasters were interspersed with the sparse
  rasters. All the rasters were then co-aligned and a loop pixel and a
  background pixel were selected for detailed analysis. Differential
  emission measure was performed on the background-subtracted CDS
  intensities to determine the temporal evolution of the loop pixel
  plasma. Solar physics research at the University of Memphis is supported
  by NSF ATM-0402729 and NASA NNG05GE68G.

Title: Coronal Diagnostics Spectrometer Observations of Coronal Loops
Authors: Nasraoui, Kaouther; Schmelz, J. T.; Cirtain, J. W.; Del Zanna,
   G.; DeLuca, E. E.; Mason, H. E.
Bibcode: 2007AAS...210.9122N
Altcode: 2007BAAS...39..207N
  Two side by side loops from the solar disk were analyzed. These two
  loops were observed with the Coronal Diagnostics Spectrometer on
  SOHO on 2003 January 17. The first loop was best seen in Mg IX at
  a wavelength of 368 angstroms and a peak formation temperature of
  Log T = 6.0. Seven pixels on the loop and one background pixel were
  chosen. The intensity of the background pixel was subtracted from each
  of the loop pixels. Only the lines that had a significant intensity
  after background subtraction were considered. A differential emission
  measure (DEM) curve was constructed for the background subtracted data
  using the forward folding technique. The DEM for most of these pixels
  had a spike shape at Log T equal to 5.85. This result shows that the
  loop is isothermal at most of these pixels. The second loop was best
  seen in Si XII at a wavelength of 520 angstroms and a peak formation
  temperature of Log T = 6.3. The same procedure was followed for the
  data analysis. After background subtraction only some hot lines had a
  significant intensity and a DEM curve was constructed for each loop
  pixel. This time the DEM is broader with a shape that shows that
  the loop plasma is multithermal with a log temperature range of 6.1
  to 6.5. <P />Solar physics research at the University of Memphis is
  supported by NSF ATM-0402729 and NASA NNG05GE68G.

Title: Coronal Diagnostic Spectrometer Observations of Isothermal
    and Multithermal Coronal Loops
Authors: Schmelz, J. T.; Nasraoui, K.; Del Zanna, G.; Cirtain, J. W.;
   DeLuca, E. E.; Mason, H. E.
Bibcode: 2007ApJ...658L.119S
Altcode:
  A data set obtained on 2003 January 17 with the Coronal Diagnostic
  Spectrometer (CDS) shows two loops sitting side by side on the solar
  disk. These loops are oriented along the CDS slit, so all pixels in
  each loop were observed simultaneously. So, although the instrument
  has a relatively slow time cadence, changes as a function of time
  that may occur during the CDS raster buildup will not affect the loop
  temperature results. Differential emission measure (DEM) analysis
  using a forward-folding technique shows different results for the
  two loops. For the first loop, the intensities of the lines that
  remain after background subtraction are well fit with a DEM curve that
  collapses to a single spike. In other words, the loop plasma at this
  location is isothermal. This analysis is confirmed with an emission
  measure loci method and agrees with the results obtained recently
  by other authors that show that the moderate spatial resolution
  of CDS can detect isothermal structures. For the second loop, the
  background-subtracted line intensities require a broad DEM, not
  consistent with isothermal plasma. This conclusion is confirmed with
  an automatic-inversion DEM method. In this Letter, we specifically
  address some of the concerns raised about CDS temperature analysis:
  the slow CDS temporal resolution, the moderate CDS spatial resolution,
  the inherent smoothing associated with DEM inversion, and line-of-sight
  effects on the DEM distribution.

Title: Active Region Loops: Temperature Measurements as a Function
    of Time from Joint TRACE and SOHO CDS Observations
Authors: Cirtain, J. W.; Del Zanna, G.; DeLuca, E. E.; Mason, H. E.;
   Martens, P. C. H.; Schmelz, J. T.
Bibcode: 2007ApJ...655..598C
Altcode:
  In this paper, we aim to quantitatively investigate the structure
  and time variation of quiescent active region loop structures. We
  coordinated a joint program of observations (JOP 146) using TRACE, to
  obtain high-cadence EUV images, and SOHO CDS, to obtain spectroscopic
  data. Loop intensities are used to determine temperature as a function
  of time for a single loop, taking full account of the background
  emission. In many locations, the emission measure loci are consistent
  with an isothermal structure. However, the results indicate significant
  changes in the loop temperature (between 1 and 2 MK) over the 6 hr
  observing period. It is possible that the loop structures are composed
  of multiple, independently heated strands with sizes less than the
  resolution of the imager and spectrometer.

Title: A benchmark study for CHIANTI based on RESIK solar flare
    spectra
Authors: Chifor, C.; Del Zanna, G.; Mason, H. E.; Sylwester, J.;
   Sylwester, B.; Phillips, K. J. H.
Bibcode: 2007A&A...462..323C
Altcode:
  Aims:To perform a benchmark analysis for the recent version of the
  CHIANTI atomic database (v. 5.2) based on high-resolution solar
  flare X-ray spectra in the range 3.4-6.1 Å from the RESIK crystal
  spectrometer on the CORONAS-F spacecraft. <BR />Methods: A C5.8 flare
  occurring on 2003 February 22 was chosen for analysis. RESIK spectra
  of this flare include emission lines of He-like and H-like K, Ar,
  S, and Si, with some dielectronic lines. Initially, two independent
  plasma diagnostic techniques are employed: an emission measure
  (EM) loci analysis using the line flux and the line contribution
  function G(T_e, N_e), and a new method based on continuum fluxes and
  contribution functions. We further apply a differential emission measure
  (DEM) analysis, from which CHIANTI synthetic spectra are derived. The
  continuum from RESIK spectra is checked against simultaneous RHESSI and
  GOES observations. Comparisons of CHIANTI synthetic spectra with those
  from the MEKAL code in the 3.4-6.1 Å range are also presented. <BR
  />Results: The emitting plasma appears multi-thermal, having one
  dominant temperature component determined independently from the line
  and continuum EM loci and DEM analyses. Consistency between line
  and continuum emissions requires photospheric elemental abundances
  (Asplund et al. 2005), with a depleted sulphur abundance. With the
  exception of RESIK channel 4 (5.0-6.1 Å), we find overall very
  good agreement between the calculated and observed intensities. From
  comparisons with other instruments, RESIK's precision in the continuum
  level is confirmed to be within the estimated 20% uncertainties in the
  intensity calibration. We find general agreement between CHIANTI and
  MEKAL isothermal spectra, but we note that the atomic data for the
  Si xii and Si xiii ions contained in CHIANTI are more complete. <BR
  />Conclusions: .RESIK observations of both lines and continua are
  suitable for characterising the properties of the flaring plasma such
  as temperature, emission measure and elemental abundance. These spectra
  can be used to evaluate any atomic database.

Title: EIT and TRACE responses to flare plasma
Authors: Tripathi, D.; Del Zanna, G.; Mason, H. E.; Chifor, C.
Bibcode: 2006A&A...460L..53T
Altcode: 2008arXiv0802.3852T
  Aims.To understand the contribution of active region and flare
  plasmas to the λ195 channels of SOHO/EIT (Extreme-ultraviolet Imaging
  Telescope) and TRACE (Transition Region and Coronal Explorer).<BR />
  Methods: .We have analysed an M8 flare simultaneously observed by
  the Coronal Diagnostic Spectrometer (CDS), EIT, TRACE and RHESSI. We
  obtained synthetic spectra for the flaring region and an outer region
  using the differential emission measures (DEM) of emitting plasma based
  on CDS and RHESSI observations and the CHIANTI atomic database. We
  then predicted the EIT and TRACE count rates.<BR /> Results: .For the
  flaring region, both EIT and TRACE images taken through the λ195
  filter are dominated by Fe XXIV (formed at about 20 MK). However,
  in the outer region, the emission was primarily due to the Fe XII,
  with substantial contributions from other lines. The average count
  rate for the outer region was within 25% the observed value for EIT,
  while for TRACE it was a factor of two higher. For the flare region,
  the predicted count rate was a factor of two (in case of EIT) and
  a factor of three (in case of TRACE) higher than the actual count
  rate.<BR /> Conclusions: .During a solar flare, both TRACE and EIT
  λ195 channels are found to be dominated by Fe XXIV emission. Reasonable
  agreement between predictions and observations is found, however some
  discrepancies need to be further investigated.

Title: The Gradual Phase of the X17 Flare on October 28, 2003
Authors: del Zanna, G.; Schmieder, B.; Mason, H.; Berlicki, A.;
   Bradshaw, S.
Bibcode: 2006SoPh..239..173D
Altcode: 2006SoPh..239..173Z; 2006SoPh..tmp...74Z
  We present SOHO/CDS observations taken during the gradual phase of
  the X17 flare that occurred on October 28, 2003. The CDS data are
  supplemented with TRACE and ground-based observations. The spectral
  observations allow us to determine velocities from the Doppler
  shifts measured in the flare loops and in the two ribbon kernels,
  one hour and a half after the flare peak. Strong downflows (&gt;70 km
  s<SUP>-1</SUP>) are observed along the loop legs at transition-region
  temperatures. The velocities are close to those expected for free
  fall. Observations and results from a hydrodynamic simulation are
  consistent with the heating taking place for a short time near the
  top of the arcade. Slight upflows are observed in the outer edges of
  the ribbons (&lt;60 km s<SUP>-1</SUP>) in the EUV lines formed at log
  T &lt; 6.3. These flows could correspond to the so-called “gentle
  evaporation.” At “flare” temperatures (Fe xix, log T = 6.9),
  no appreciable flows are observed. The observations are consistent
  with the general standard reconnection models for two-ribbons flares.

Title: The early phases of a solar prominence eruption and associated
flare: a multi-wavelength analysis
Authors: Chifor, C.; Mason, H. E.; Tripathi, D.; Isobe, H.; Asai, A.
Bibcode: 2006A&A...458..965C
Altcode:
  Aims.We aim to examine the precursor phases and early evolution of a
  prominence eruption associated with a M4-class flare and a partial
  halo coronal mass ejection (CME) observed on 2005 July 27. Our
  main goal is to investigate the precursor eruption signatures
  observed in EUV, X-ray and microwave emission and their relation
  to the prominence destabilisation. <BR /> Methods: .We perform a
  multi-wavelength study of the prominence morphology and motion using
  high-cadence and spatial resolution EUV 171 Å images from the TRACE
  satellite. The high-temperature flare radiative emission in soft
  and hard X-rays are analysed through imaging and spectral modeling
  with RHESSI. Complementary microwave images (17 GHz and 34 GHz)
  from NoRH are also investigated.<BR /> Results: .The activation
  of the filament proceeds from one anchored footpoint. We observe
  "pre-eruption" brightenings in X-ray and EUV images, close to the
  erupting footpoint of the prominence, being temporally correlated to
  the point when the prominence first enters a slow-rise phase, and then
  an accelerated fast-rise phase. The brightness temperature (T_b) of the
  prominence at 34 GHz is increasing during the eruption. We also find
  very good correlation between the prominence height-time profile and
  the spatially integrated soft X-ray (SXR) emission.<BR /> Conclusions:
  .We discuss the observed precursor brightenings with respect to possible
  mechanisms that might be responsible for the prominence destabilisation
  and acceleration. Our observations suggest that reconnection events
  localised beneath the erupting footpoint may eventually destabilise
  the entire prominence, causing the eruption.

Title: Phosphorus distribution in calcite speleothems from solid-state
    NMR and AFM
Authors: Mason, H. E.; Hausner, D.; Frisia, S.; Tang, Y.; Reeder,
   R. J.; Strongin, D. R.; Phillips, B. L.
Bibcode: 2006GeCAS..70Q.399M
Altcode:
  No abstract at ADS

Title: Multi-Wavelength Investigation of a Sigmoidal Active Region
Authors: Tripathi, D.; Mason, H. E.; Young, P. R.
Bibcode: 2006ESASP.617E.148T
Altcode: 2006soho...17E.148T
  No abstract at ADS

Title: Asymmetric Prominence Eruption: A "Domino Effect"?
Authors: Chifor, C.; Mason, H. E.; Tripathi, D.; Isobe, H.; Asai, A.
Bibcode: 2006ESASP.617E.121C
Altcode: 2006soho...17E.121C
  No abstract at ADS

Title: On the propagation of brightening after filament/prominence
    eruptions, as seen by SoHO-EIT
Authors: Tripathi, D.; Isobe, H.; Mason, H. E.
Bibcode: 2006A&A...453.1111T
Altcode:
  Aims.To study the relationship between the propagation of brightening
  and erupting filaments/prominences in order to get some insight into
  the three-dimensional picture of magnetic reconnection.<BR /> Methods:
  .Analysis of the observations taken with the EIT (Extreme-ultraviolet
  Imaging Telescope) aboard SoHO (Solar and Heliospheric Observatory).<BR
  /> Results: .When the prominences/filaments erupted having one point
  fixed - asymmetric eruption - the brightening propagated along the
  neutral line together with the expansion/separation from the polarity
  inversion line (PIL) as expected from the standard models. However
  in case of symmetric eruptions, the brightening propagated towards
  both end points starting at the middle. When the prominence/filament
  erupted faster then the speed of the propagating brightening was
  faster and vice-versa.<BR /> Conclusions: .Based on these observations
  we conclude that the eruption and magnetic reconnection - propagation
  (along the PIL) and separation (away from PIL) of the brightening - are
  dynamically coupled phenomena. These observations can be explained by
  a simple extension of the 2D models illustrating eruption and magnetic
  reconnection to a 3D model.

Title: SOHO/CDS Observations of Quiescent Active Region Loops
Authors: Del Zanna, G.; Mason, H. E.; Cirtain, J.
Bibcode: 2006ESASP.617E..86D
Altcode: 2006soho...17E..86D
  No abstract at ADS

Title: The Coronal Loop Controversy: Resolved!
Authors: Schmelz, Joan T.; Nasraoui, K.; Cirtain, J.; DeLuca, E.;
   Del Zanna, G.; Mason, H.
Bibcode: 2006SPD....37.1701S
Altcode: 2006BAAS...38..245S
  Critics have pointed out the shortcomings of CDS coronal loop
  temperature analysis - the large pixel size and the slow time
  cadence. It is these limitations, some say, that have produced
  multithermal results for the loop observed with CDS on 1998 April
  20, both along the line of sight and along the loop length. Analysis
  of the CDS observations of AR 10250 from 2003 January 17, however,
  seem to contradict these critics. Two loops sit side-by-side right
  along the slit in this raster, so all pixels in each loop were
  observed at the same time. As a result changes as a function of time
  will not affect the temperature results. The first loop is observed
  primarily in Mg IX (Log T = 6.0) and the second in Si XII (Log T =
  6.3). Differential Emission Measure (DEM) analysis of background
  subtracted line intensities of pixels in each loop show distinctly
  different results. For the first loop, the intensities of the lines
  that remain after background subtraction are well fit with a DEM that
  collapses to a single spike. In other words, the loop plasma at this
  location is isothermal. This proves that it is neither the DEM method
  nor the CDS pixel size that produced the multithermal distributions
  for the 1998 April 20 loop plasma. In addition the DEM distribution for
  the second loop is similar to those produced for the 1998 April 20 loop
  and is clearly inconsistent with isothermal plasma. Both distributions
  change as a function of position along the loop, with the temperatures
  increasing with loop height. Solar physics research at the University
  of Memphis is supported by grants from NSF and NASA.

Title: Exploring High Time Resolution Coronal Dynamics with the
    Rapid Acquisition Imaging Spectrograph (RAISE) Sounding Rocket Program
Authors: Hassler, Donald W.; DeForest, C. E.; McIntosh, S.; Slater,
   D.; Ayres, T.; Thomas, R.; Scheuhle, U.; Michaelis, H.; Mason, H.
Bibcode: 2006SPD....37.3706H
Altcode:
  The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
  high resolution imaging spectrograph to study the dynamics of the
  solar chromosphere and corona on time scales as short as 100 ms. High
  speed imaging from TRACE has shown that rapid motions and reconnection
  are central to the physics of the transition region and corona, but
  cannot resolve the differences between propagating phenomena and bulk
  motion. SoHO/CDS and SoHO/SUMER have yielded intriguing measurements
  of motion and heating in the solar atmosphere, and Solar-B/EIS will
  capture EUV spectra of flares in progress; but no currently planned
  instrument can capture spectral information in the chromosphere,
  transition region, or cool corona on the 1-10 Hz time scale required for
  few-second cadence spectral imaging or rapid wave motion studies. RAISE
  is uniquely suited to exploring this hard-to-reach domain.The first
  flight of RAISE is scheduled for October 24, 2006 (Flight 36.219 US)
  and will focus on the study of high frequency, small-scale dynamics
  of active region structures and the high frequency wave structure
  associated with these active regions.

Title: A Multi-Wavelength Study of the Compact M1 Flare on October
    22, 2002
Authors: Zanna, G. Del; Berlicki, A.; Schmieder, B.; Mason, H. E.
Bibcode: 2006SoPh..234...95Z
Altcode:
  In this paper we present a further study of the Ml class
  flare observed on October 22, 2002. We focus on the SOHO Coronal
  Diagnostic Spectrometer (CDS) spectral observations performed during a
  multi-wavelength campaign with TRACE and ground-based instruments (VTT,
  THEMIS). Strong blue-shifts are observed in the CDS coronal lines in
  flare kernels during the impulsive phase of this flare. From a careful
  wavelength calibration we deduce upflows of 140 km/s for the Fe XIX
  flare emission, with a pattern of progressively smaller flows at lower
  temperatures. Large line-widths were observed, especially for the Fe XIX
  line, which indicate the existence of turbulent velocities. The strong
  upflows correspond to full shifts of the line profiles. These flows
  are observed at the initial phase of the flare, and correspond to the
  "explosive evaporation". The regions of the blueshifted kernels, a few
  arc seconds away from the flare onset location, could be explained by
  the chain reaction of successive magnetic reconnections of growing
  emerging field line with higher and higher overlying field. This
  interpretation is evidenced by the analysis of the magnetic topology
  of the active region using a linear force-free-field extrapolation of
  THEMIS magnetograms.

Title: A Multi-Wavelength Study of the Compact M1 Flare on October
    22, 2002
Authors: del Zanna, G.; Berlicki, A.; Schmieder, B.; Mason, H. E.
Bibcode: 2006SoPh..234...95D
Altcode: 2006SoPh..234...95Z
  In this paper we present a further study of the Ml class
  flare observed on October 22, 2002. We focus on the SOHO Coronal
  Diagnostic Spectrometer (CDS) spectral observations performed during a
  multi-wavelength campaign with TRACE and ground-based instruments (VTT,
  THEMIS). Strong blue-shifts are observed in the CDS coronal lines in
  flare kernels during the impulsive phase of this flare. From a careful
  wavelength calibration we deduce upflows of 140 km/s for the Fe XIX
  flare emission, with a pattern of progressively smaller flows at lower
  temperatures. Large line-widths were observed, especially for the Fe
  XIX line, which indicate the existence of turbulent velocities. The
  strong upflows correspond to full shifts of the line profiles. These
  flows are observed at the initial phase of the flare, and correspond
  to the “explosive evaporation”. The regions of the blueshifted
  kernels, a few arc seconds away from the flare onset location, could be
  explained by the chain reaction of successive magnetic reconnections of
  growing emerging field line with higher and higher overlying field. This
  interpretation is evidenced by the analysis of the magnetic topology
  of the active region using a linear force-free-field extrapolation of
  THEMIS magnetograms.

Title: X-ray emission from PTT stars
Authors: Del Zanna, G.; Worters, H. L.; Bromage, G. E.; Foley, C. A.;
   Mason, H. E.; Landini, M.; Whiting, A.
Bibcode: 2006AdSpR..38.1475D
Altcode:
  We present preliminary results on an XMM-Newton observation dedicated to
  Post-T-Tauri (PTT) stars. We observed the visual binary 2RE J0241-53 of
  the Horologium association of nearby PTT stars. The XMM observations
  have been complemented with ground-based optical spectroscopy and
  photometry. Several flares have been observed. The X-ray spectrum of
  the brightest star during quiescence indicates a rather cool corona
  (with no emission at temperatures ⩾10 MK) more similar to that of the
  Classical T-Tauri star TW Hya (observed with Chandra and XMM-Newton)
  and at variance with that of another PTT Star (PZ Tel) observed with
  Chandra. Approximate analysis shows large Ne/Fe, N/Fe, C/Fe abundances
  (compared to solar photospheric values).

Title: CHIANTI-An Atomic Database for Emission Lines. VII. New Data
    for X-Rays and Other Improvements
Authors: Landi, E.; Del Zanna, G.; Young, P. R.; Dere, K. P.; Mason,
   H. E.; Landini, M.
Bibcode: 2006ApJS..162..261L
Altcode:
  The CHIANTI atomic database contains atomic energy levels, wavelengths,
  radiative transition probabilities, and collisional excitation data for
  a large number of ions of astrophysical interest. CHIANTI also includes
  a suite of IDL routines to calculate synthetic spectra and carry out
  plasma diagnostics. Version 5 has been released, which includes several
  new features, as well as new data for many ions. The new features in
  CHIANTI are as follows: the inclusion of ionization and recombination
  rates to individual excited levels as a means to populate atomic
  levels; data for Kα and Kβ emission from Fe II to Fe XXIV; new data
  for high-energy configurations in Fe XVII to Fe XXIII; and a complete
  reassessment of level energies and line identifications in the X-ray
  range, multitemperature particle distributions, and photoexcitation
  from any user-defined radiation field. New data for ions already in
  the database, as well as data for ions not present in earlier versions
  of the database, are also included. Version 5 of CHIANTI represents a
  major improvement in the calculation of line emissivities and synthetic
  spectra in the X-ray range and expands and improves theoretical spectra
  calculations in all other wavelength ranges.

Title: Dynamics of Active Region Loops: Temperature Measurements as
    a function of Time
Authors: Cirtain, J. J.; del Zanna, G.; Mason, H.; Deluca, E.;
   Martens, P.
Bibcode: 2005AGUFMSH44A..03C
Altcode:
  The combination of moderate resolution EUV spectroscopy and high
  resolution narrow band filter images provides the most accurate
  measure of temperature and density for coronal loops to date. We will
  demonstrate our technique for combining the data sets from the Coronal
  Diagnostic Spectrometer on SoHO and the Transition Region and Coronal
  Explorer. Background subtracted spectral intensities are used to
  determine the temperature of coronal loops and the TRACE images help
  determine the loop cross-section, temporal variability, and filling
  factor. The resulting temperature profiles for multiple positions along
  a loop leg are determined using the EM LOCI method, and a technique for
  determining whether a single temperature can characterize the plasma is
  also presented. We compare the results of our study to current models.

Title: Flows and Heating of the Solar Atmosphere during Solar Flares
Authors: Schmieder, B.; Berlicki, A.; Li, H.; Del Zanna, G.; Mason, H.
Bibcode: 2005ESASP.592..543S
Altcode: 2005soho...16E.102S; 2005ESASP.592E.102S
  No abstract at ADS

Title: Recent developments of the CHIANTI database in the X-ray
    wavelength range
Authors: Landi, E.; Dere, K. P.; Young, P. R.; del Zanna, G.; Mason,
   H. E.; Landini, M.
Bibcode: 2005AIPC..774..409L
Altcode:
  CHIANTI is a database of atomic data and transition probabilities that
  allows the calculation of synthetic spectra and plasma diagnostics of
  optically thin plasmas. It is primarily suited for wavelengths shorter
  than 2000 Å but in principle can also be used at longer wavelengths. In
  the present paper we illustrate the latest development of the CHIANTI
  database, that include a huge expansion of the database in the X-ray
  wavelength range, the renewal of several data in the EUV range, and
  the inclusion of ionization and recombination in the level population
  calculation. This enhanced database will constitute the Version 5
  of CHIANTI.

Title: EUV Observations of Active Region Dynamics
Authors: Deluca, E. E.; Cirtain, J. W.; del Zanna, G.; Mason, H. E.;
   Martens, P. C.; Schmelz, J.; Golub, L.
Bibcode: 2005AGUSMSP33A..03D
Altcode:
  Data collected during SoHO JOP 146, in collaboration with TRACE, is
  used to investigate the physical characteristics of coronal active
  region loops as a function of time and position along and across
  loop structures. These data include TRACE images in all three EUV
  passbands, and simultaneous CDS spectroscopic observations. Preliminary
  measurements of the loop temperature both along the loop half-length
  and loop cross-section are presented as a function of time. We will
  show the temperature and density profiles of several structures as a
  function of position, show changes in temperature and density with time
  and characterize the coronal background emission. Questions raised
  by these results will be greatly advanced with the high resolution
  spectra available from the EIS on Solar-B.

Title: Benchmarking atomic data for astrophysics: Fe XII
Authors: Del Zanna, G.; Mason, H. E.
Bibcode: 2005A&A...433..731D
Altcode:
  We use recently calculated electron collisional data by [CITE] for
  ion{Fe}{xii} (n=3 configurations) to build a model ion to compare
  to spectroscopic observations of the solar corona and laboratory
  measurements. We review all the line identifications of the brightest
  lines, by comparing both wavelengths and line intensities. The
  presence of blends in different plasma conditions is highlighted. A
  large number of new energy levels and line identifications are
  proposed. In particular, we identify the electric quadrupole
  ^4P{5/2}^e-^4F{9/2}<SUP>e</SUP> transition with the bright coronal
  line observed at 592.6 Å, previously unidentified. This line, when
  observed with the 1242.0, 1349.5 UV forbidden lines, is a good density
  diagnostic over a large range of electron densities. We also indicate
  the best spectral lines to be used for density diagnostics or instrument
  calibration. From various combinations of lines we obtain electron
  densities that are significantly different from those published in the
  previous literature. Some examples are provided. The agreement between
  theory and experimental data in terms of wavelengths, line intensities
  and level lifetimes is excellent. <P />The full datasets of energies
  (Table 2) and radiative data (Table 3) are only available in electronic
  form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
  or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/731

Title: Atomic data from the IRON Project
Authors: Storey, P. J.; Del Zanna, G.; Mason, H. E.; Zeippen, C. J.
Bibcode: 2005A&A...433..717S
Altcode:
  A new calculation of rate coefficients for electron collisional
  excitation of ion{Fe}{xii} is presented and compared to earlier
  calculations. Significant differences are found with all earlier work
  due to the inclusion of resonance processes that have not previously
  been considered and to the use of the intermediate coupling frame
  transformation method. The resulting dataset of collision strengths
  is shown to resolve many of the outstanding discrepancies between
  theory and solar observations. In particular, density sensitive
  line ratios in ion{Fe}{xii} now indicate electron densities
  close to those derived from other ions of comparable ionization
  potential. <P />Table 10 is only available in electronic form at the
  CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
  http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/433/717

Title: Multialtitude Observations of a Coronal Jet during the Third
    Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
   Strachan, L.; Holzer, T.; Gilbert, H.; Cyr, O. C. St.; Thompson, B. J.;
   Pike, C. D.; Mason, H. E.; Burkepile, J.; Thompson, W.; Fletcher, L.
Bibcode: 2005ApJ...623..519K
Altcode:
  On 1999 August 26, a coronal jet occurred at the northwest limb near
  a sigmoid active region (AR 8668) that was the target for a joint
  observation plan (SOHO joint observing program 106) during the third
  Whole Sun Month Campaign. This jet was observed by several instruments
  at the limb (SOHO/CDS, SOHO/EIT, TRACE, and Mauna Loa Solar Observatory
  CHIP and PICS) and at 1.64 R<SUB>solar</SUB> (SOHO/UVCS). At the limb,
  this jet event displayed both low- and high-temperature components. Both
  high- and low-temperature components were evident during the early phase
  (first 20 minutes) of the event. However, the low-temperature component
  is maintained for ~1 hr after the higher temperature component is
  gone. There is a second brightening (a possible second jet) seen by
  EIT and TRACE about 50 minutes after the onset of the first jet. The
  line-of-sight motion at the limb began with a 300 km s<SUP>-1</SUP>
  redshift and evolved to a 200 km s<SUP>-1</SUP> blueshift. At
  1.64 R<SUB>solar</SUB>, the intensities of Lyα and Lyβ in the jet
  increased by a factor of several hundred compared with the background
  corona. The C III λ977 line also brightened significantly. This
  indicates low-temperature [~(1-2)×10<SUP>5</SUP> K] emission in the
  jet, while the intensities of O VI λ1032 and O VI λ1037 increased
  by as much as a factor of 8. The UVCS data show evidence of heating at
  the early phase of the event. The Doppler shift in the lines indicates
  that the line-of-sight (LOS) velocity in the jet started from ~150
  km s<SUP>-1</SUP> in blueshift and ended at ~100 km s<SUP>-1</SUP>
  in redshift. This LOS motion seen at 1.64 R<SUB>solar</SUB> was
  apparently opposite to what was observed when the jet emerged from the
  limb. The Doppler dimming analysis indicates that the radial outflow
  speed correlates with the magnitude of the LOS speed. Interestingly,
  UVCS observations at 2.33 and 2.66 R<SUB>solar</SUB> show no trace of
  the jet and SOHO/LASCO observations also yield no firm detection. We
  find that a simple ballistic model can explain most of the dynamical
  properties of this jet, while the morphology and the thermal properties
  agree well with reconnection-driven X-ray jet models.

Title: Benchmarking atomic data for astrophysics: Fe XXIII
Authors: Del Zanna, G.; Chidichimo, M. C.; Mason, H. E.
Bibcode: 2005A&A...432.1137D
Altcode:
  Recent scattering calculations for Fe XXIII are benchmarked against
  laboratory and astrophysical observations. The collisional data are
  supplemented by radiative data obtained with empirical adjustments
  that take into account observed wavelengths. All previous line
  identifications and energy levels are reviewed and assessed in light
  of these new calculations. Most of the previous identifications,
  in particular of the astrophysically-important spectral lines are
  confirmed. However, some identification are rejected or questioned, and
  new ones proposed. The agreement between theoretical and experimental
  data in terms of wavelengths, line intensities and level lifetimes is
  very good. Observations of Fe XXIII L-shell emission lines provide
  a great opportunity to directly measure electron temperatures for
  a wide range of astrophysical sources. Examples from solar (SMM,
  SOLEX) and stellar (Chandra, EUVE) observations are provided. <P
  />The full set of energies (cf. Table 2), wavelengths and A-values
  (cf. Table 3) are available in electronic form at the CDS via
  anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
  http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/432/1137 .

Title: VizieR Online Data Catalog: Fe XXIII Benchmarking (Del
    Zanna+, 2005)
Authors: Del Zanna, G.; Chidichimo, M. C.; Mason, H. E.
Bibcode: 2005yCat..34321137D
Altcode:
  Recent scattering calculations for Fe XXIII are benchmarked against
  laboratory and astrophysical observations. The collisional data are
  supplemented by radiative data obtained with empirical adjustments
  that take into account observed wavelengths. All previous line
  identifications and energy levels are reviewed and assessed in light
  of these new calculations. Most of the previous identifications,
  in particular of the astrophysically-important spectral lines are
  confirmed. However, some identification are rejected or questioned, and
  new ones proposed. The agreement between theoretical and experimental
  data in terms of wavelengths, line intensities and level lifetimes is
  very good. Observations of Fe XXIII L-shell emission lines provide
  a great opportunity to directly measure electron temperatures for
  a wide range of astrophysical sources. Examples from solar (SMM,
  SOLEX) and stellar (Chandra, EUVE) observations are provided. <P
  />**************************************************************************
  * * * Sorry, but the author(s) never supplied
  the tabular material * * announced in the paper * * *
  **************************************************************************
  <P />(1 data file).

Title: VizieR Online Data Catalog: Atomic data from the IRON
    Project. LVI. (Chidichimo+, 2005)
Authors: Chidichimo, M. C.; Del Zanna, G.; Mason, H. E.; Badnell,
   N. R.; Tully, J. A.; Berrington, K. A.
Bibcode: 2005yCat..34300331C
Altcode:
  Collision strengths for electron induced transitions in
  the beryllium-like ion Fe<SUP>+22</SUP> are calculated
  using the intermediate coupling frame transformation
  (ICFT) version of the R-matrix programs. Our target
  has 98 fine structure states ls<SUP>2</SUP> nl n'l'SLJ
  corresponding to n=2 and n'=2, 3, 4. The present calculation
  is for electron impact energies in the range 3.15 to 380Ry. <P
  />**************************************************************************
  * * * Sorry, but the author(s) never supplied
  the tabular material * * announced in the paper * * *
  **************************************************************************
  <P />(1 data file).

Title: VizieR Online Data Catalog: Fe X Benchmarking atomic data
    (Del Zanna+, 2004)
Authors: Del Zanna, G.; Berrington, K. A.; Mason, H. E.
Bibcode: 2005yCat..34220731D
Altcode:
  This is the first in a series of papers in which we benchmark recent
  atomic data available for astrophysical applications. We review various
  issues related to the completeness and accuracy of both theoretical and
  experimental data. In this paper, the available experimental and atomic
  data for Fe X (n=3 configurations) are reviewed and assessed. New
  collisional and radiative data are calculated to supplement
  published data. The radiative calculations are done with empirical
  adjustements that take into account observed wavelengths. Previous
  line identifications are also reviewed and assessed. Our approach
  focuses on the brightest spectral lines, and uses both wavelengths and
  line intensities to assess the line identifications on a quantitative
  basis. Although many previous line identifications are confirmed, some
  are rejected (e.g. the coronal line observed at 1582.35{AA}). We confirm
  previously suggested identifications (e.g. 257.262{AA},1028.02{AA}),
  and we present new ones, (e.g. the lines of the 3s<SUP>2</SUP>
  3p<SUP>4</SUP> 3d-3s 3p<SUP>5</SUP> 3d transition array). In addition,
  we highlight the presence of blends and we review which spectral lines
  are best for density diagnostics or for instrument calibration. The
  theoretical data (line intensities and level lifetimes) are benchmarked
  against well-calibrated spectroscopic observations of the solar corona
  and laboratory measurements. The agreement between theoretical and
  experimental data which we achieve with our new model ion is very
  good. <P />(3 data files).

Title: The CHIANTI database
Authors: Landi, E.; Dere, K. P.; Young, P. R.; Landini, M.; Mason,
   H. E.; Del Zanna, G.
Bibcode: 2005HiA....13..653L
Altcode:
  CHIANTI is a database of atomic data and transition rates necessary for
  calculating synthetic spectra and carrying out plasma diagnostics of
  astrophysical sources in the X-ray EUV and UV wavelength ranges. CHIANTI
  includes both line and continuum emission from all astrophysically
  abundant elements in the universe. All data are taken from refereed
  literature and are critically assessed. CHIANTI also includes a suite
  of IDL programs that allow spectroscopic analysis to be carried
  out. CHIANTI data and software are freely distributed over the
  internet. <P />In the present talk I will describe the contents of
  the CHIANTI database its current status and the areas where CHIANTI
  is being developed and I will also present a comparison of CHIANTI
  predictions with the X-ray emission from astrophysical sources.

Title: Atomic data from the IRON Project = 2, 3, 4 configurations.
    LVI. Electron excitation of Be-like Fe XXIII for the n = 2,3,4
    configurations
Authors: Chidichimo, M. C.; Del Zanna, G.; Mason, H. E.; Badnell,
   N. R.; Tully, J. A.; Berrington, K. A.
Bibcode: 2005A&A...430..331C
Altcode:
  Collision strengths for electron induced transitions in the
  beryllium-like ion Fe<SUP>+22</SUP> are calculated using the
  intermediate coupling frame transformation (ICFT) version of
  the R-matrix programs. Our target has 98 fine structure states
  1s<SUP>2</SUP> nl n'l' SLJ corresponding to n = 2 and n' = 2, 3,
  4 . The present calculation is for electron impact energies in the
  range 3.15 to 380 Ry. When T exceeds about ten million degrees one
  needs to take account of contributions to the thermally averaged
  collision strength Υ coming from electrons with energies in excess of
  380 Ry. We discuss a way of allowing for these contributions. Values
  of Υ for all the transitions between the ground state and the
  excited states 1s<SUP>2</SUP> 2l n l n'l' S'L'J', with n'=2,3,4 are
  tabulated as a function of log T. The temperature range 6.3 ≤log
  T ≤8.1 is centred on log T = 7.1 which is approximately where
  Fe<SUP>+22</SUP> has maximum abundance in ionization equilibrium. To
  the best of our knowledge these are the first R-matrix calculations
  for Fe<SUP>+22</SUP> for excitations to the n = 3,4 levels. Good
  agreement with previous distored-wave calculations is found. However,
  the resonance contributions have an important effect on the effective
  collision strengths and in turn on the level populations. <P
  />Full Tables 2, 4 and 6 are only available in electronic form at
  the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5)
  or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/331. The
  full datasets of wavelengths and gf values (Table 4) and of
  effective collision strengths (Table 7) are only available at
  the same address. The same data are also available at the TIPbase
  (http://vizier.u-strasbg.fr/tipbase/home.html) database and as an
  `adf04' file at the Oak Ridge National Laboratory's database via
  http://www-cfadc.phy.ornl.gov/

Title: Spectral diagnostic capabilities of Solar-B EIS
Authors: Zanna, G. Del; Mason, H. E.
Bibcode: 2005AdSpR..36.1503Z
Altcode:
  In this paper, we provide simulated intensities for Solar-B EIS to
  aid in the scientific planning for Solar-B. These simulations are
  obtained with the latest atomic data and EIS response functions. We
  also report on our progress in reviewing and benchmarking atomic data
  for the Fe coronal ions, that are of particular importance for spectral
  and instrument calibration purposes. We highlight the most prominent
  lines that can be used for plasma diagnostics.

Title: VizieR Online Data Catalog: Fe XII Benchmarking atomic data
    (Del Zanna+, 2005)
Authors: Del Zanna, G.; Mason, H. E.
Bibcode: 2005yCat..34330731D
Altcode:
  We use recently calculated electron collisional data by Storey
  et al. (2005A&amp;A...433..717S) for Fe XII (n=3 configurations)
  to build a model ion to compare to spectroscopic observations of
  the solar corona and laboratory measurements. We review all the line
  identifications of the brightest lines, by comparing both wavelengths
  and line intensities. The presence of blends in different plasma
  conditions is highlighted. A large number of new energy levels and
  line identifications are proposed. In particular, we identify the
  electric quadrupole <SUP>4P<SUB>5/2</SUB>-</SUP>4^F<SUB>9/2</SUB>
  transition with the bright coronal line observed at 592.6{AA},
  previously unidentified. This line, when observed with the 1242.0,
  1349.5 UV forbidden lines, is a good density diagnostic over a large
  range of electron densities. We also indicate the best spectral lines
  to be used for density diagnostics or instrument calibration. From
  various combinations of lines we obtain electron densities that
  are significantly different from those published in the previous
  literature. Some examples are provided. The agreement between theory
  and experimental data in terms of wavelengths, line intensities and
  level lifetimes is excellent. <P />(2 data files).

Title: Remote Sensing of Plasma Diagnostics Relating to Coronal
    Heating
Authors: Mason, H. E.; Del Zanna, G.; Bradshaw, S.
Bibcode: 2004ESASP.575..312M
Altcode: 2004soho...15..312M
  No abstract at ADS

Title: Synthesised Radiative Emission from a Nanoflare Heated
    Elemental Solar Loop
Authors: Bradshaw, S. J.; Del Zanna, G.; Mason, H. E.; Cargill, P. J.
Bibcode: 2004ESASP.575..539B
Altcode: 2004soho...15..539B
  No abstract at ADS

Title: On the consequences of a non-equilibrium ionisation balance
    for compact flare emission and dynamics
Authors: Bradshaw, S. J.; Del Zanna, G.; Mason, H. E.
Bibcode: 2004A&A...425..287B
Altcode:
  We carry out a hydrodynamic simulation of a compact flare and find
  significant non-equilibrium distributions for the ionisation balance
  during the impulsive and gradual phases, which can strongly alter the
  radiative emission. This has major implications for attempts to derive
  the theoretical intensities of emission lines used for spectroscopic
  diagnostic analyses of the plasma properties. <P />During the
  impulsive phase we find that the emissivities of He I, He II and C IV
  in the transition region can be strongly enhanced above their expected
  equilibrium values, followed by a significant reduction which increases
  the amount of chromospheric plasma ablated into the corona. Furthermore,
  during the flare heating the overall charge state of the coronal
  ions can be significantly lower than is suggested by an equilibrium
  ionisation balance and, therefore, line ratio measurements will yield
  plasma temperatures that are much greater than the formation temperature
  of the emitting ion. <P />During the gradual phase the emissivity at
  transition region temperatures remains suppressed, compared with its
  equilibrium value, with correspondingly reduced downflow velocities and
  increased radiative cooling time-scales. <P />Finally, we synthesise
  the emission as it would be detected by TRACE in its 171 Å and 195 Å
  wavelength bands, and find that the filter ratio technique can give
  reasonably good estimates of the plasma temperature in quiescence,
  though when the populations of Fe VIII, Fe IX, Fe X and Fe XII exhibit
  departures from equilibrium the temperatures derived from filter ratio
  measurements become unreliable. <P />Figures \ref{fig4}-\ref{fig39}
  are only available in electronic form at http://www.edpsciences.org

Title: Benchmarking atomic data for astrophysics: Fe X
Authors: Del Zanna, G.; Berrington, K. A.; Mason, H. E.
Bibcode: 2004A&A...422..731D
Altcode:
  This is the first in a series of papers in which we benchmark
  recent atomic data available for astrophysical applications. We
  review various issues related to the completeness and accuracy
  of both theoretical and experimental data. In this paper, the
  available experimental and atomic data for Fe X (n=3 configurations)
  are reviewed and assessed. New collisional and radiative data are
  calculated to supplement published data. The radiative calculations
  are done with empirical adjustements that take into account observed
  wavelengths. Previous line identifications are also reviewed and
  assessed. Our approach focuses on the brightest spectral lines,
  and uses both wavelengths and line intensities to assess the line
  identifications on a quantitative basis. Although many previous line
  identifications are confirmed, some are rejected (e.g. the coronal line
  observed at 1582.35 Å). We confirm previously suggested identifications
  (e.g. 257.262 Å, 1028.02 Å), and we present new ones, (e.g. the
  lines of the 3s<SUP>2</SUP>3p<SUP>4</SUP>3d-3s 3p<SUP>5</SUP>3d
  transition array). In addition, we highlight the presence of blends
  and we review which spectral lines are best for density diagnostics or
  for instrument calibration. The theoretical data (line intensities and
  level lifetimes) are benchmarked against well-calibrated spectroscopic
  observations of the solar corona and laboratory measurements. The
  agreement between theoretical and experimental data which we achieve
  with our new model ion is very good. <P />Table 1 and full Tables
  3 and \ref{tab:lines} are only available in electronic form at the
  CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
  http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/731 <P />Appendix
  is only available in electronic form at http://www.edpsciences.org

Title: High Time Cadence Observations with the Rapid Acquisition
    Imaging Spectrograph (RAISE) Rocket Program
Authors: Ayres, T. R.; Hassler, D. M.; Slater, D.; DeForest, C. E.;
   Mason, H.; McIntosh, S.; Thomas, R. J.
Bibcode: 2004AAS...204.9704A
Altcode: 2004BAAS...36..828A
  The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
  high resolution imaging spectrograph scheduled to fly on a NASA sounding
  rocket in 2006 to study the dynamics of the solar chromosphere and
  corona on time scales as short as 100 ms. High speed imaging from
  TRACE has shown that rapid motions and reconnection are central to the
  physics of the transition region and corona, but cannot resolve the
  differences between propagating phenomena and bulk motion. SoHO/CDS and
  SoHO/SUMER have yielded intriguing measurements of motion and heating
  in the solar atmosphere, and Solar-B/EIS will capture EUV spectra of
  flares in progress; but no currently planned instrument can capture
  spectral information in the chromosphere, transition region, or cool
  corona on the ∼ 1-10 Hz time scale required for few-second cadence
  spectral imaging or rapid wave motion studies. RAISE is uniquely suited
  to exploring this hard-to-reach domain. <P />This work is supported
  by NASA Grant NNG04WC01G to the Southwest Research Institute.

Title: Recent development of the CHIANTI database in the X-ray
    wavelength range
Authors: Landi, E.; Dere, K. P.; Mason, H. E.; Del Zanna, G.; Landini,
   M.; Young, P. R.
Bibcode: 2004AAS...204.7310L
Altcode: 2004BAAS...36R.801L
  CHIANTI consists of a database of critically assessed atomic data
  and transition rates to calculate line and continuum emission
  from astrophysical plasmas. <P />During the last year the CHIANTI
  database has been substantially expanded in the X-ray wavelength
  region by including a large number of new configurations and lines,
  and by including ionization and recombination processes in the level
  population calculations. <P />We will describe these improvements,
  the data we used, and illustrate examples of 1) their effects on
  predicted emissivities and on plasma diagnostics 2) applications to
  the study of flares in solar active regions

Title: Spectral diagnostic capabilities of Solar-B EIS
Authors: del Zanna, G.; Mason, H. E.
Bibcode: 2004cosp...35.3002D
Altcode: 2004cosp.meet.3002D
  We briefly review the main spectral diagnostics that will be available
  with Solar-B EIS, and what kind of scientific questions could be best
  addressed, based on our experience with SOHO/CDS observations. We then
  report on our progress in reviewing and benchmarking atomic data for
  the Fe coronal ions, that are of particular importance for spectral
  and instrument calibration purposes.

Title: Future Observations with the Rapid Acquisition Imaging
    Spectrograph (RAISE)
Authors: Hassler, D. M.; Deforest, C. E.; Slater, D.; Ayres, T.;
   Mason, H.; McIntosh, S.; Thomas, R.
Bibcode: 2004cosp...35.2280H
Altcode: 2004cosp.meet.2280H
  The Rapid Acquisition Imaging Spectrograph (RAISE) is a next-generation
  high resolution imaging spectrograph scheduled to fly on a NASA sounding
  rocket in 2006 to study the dynamics of the solar chromosphere and
  corona on time scales as short as 100 ms. High speed imaging from TRACE
  has shown that rapid motions and reconnection are central to the physics
  of the transition region and corona, but cannot resolve the differences
  between propagating phenomena and bulk motion. SoHO/CDS and SoHO/SUMER
  have yielded intriguing measurements of motion and heating in the
  solar atmosphere, and Solar-B/EIS will capture EUV spectra of flares
  in progress; but no currently planned instrument can capture spectral
  information in the chromosphere, transition region, or cool corona
  on the ~1-10 Hz time scale required for few-second cadence spectral
  imaging or rapid wave motion studies. RAISE is uniquely suited to
  exploring this hard-to-reach domain.

Title: X-ray emission from PTT stars
Authors: del Zanna, G.; Bromage, G.; Foley, C.; Worters, H.; Mason,
   H.; Landini, M.
Bibcode: 2004cosp...35.2995D
Altcode: 2004cosp.meet.2995D
  We present preliminary results on new X-ray spectroscopic XMM/RGS
  observations of the visual binary nicknamed `Horace Horologii' (2RE
  J0241-53). The two stars are strong and very active X-ray emitters, and
  are members of an association of Post-T-Tauri stars. A detailed study
  (in particular in terms of chemical composition) is important for our
  understanding of the evolution from the T-Tauri phase, and to explain
  the origin of the X-ray emission in very young stars. The physical
  characteristics of the quiescent X-ray emission are described, and
  related to other stellar parameters such as photospheric abundances and
  the rotational period. Simultaneous ground-based optical spectroscopy
  and U-band photometric monitoring observations were obtained at the
  South African Astronomical Observatory.

Title: Spectroscopic observations of compact solar flares
Authors: del Zanna, G.; Mason, H. E.
Bibcode: 2004cosp...35.2998D
Altcode: 2004cosp.meet.2998D
  We present SOHO/Coronal Diagnostic Spectrometer observations of
  solar flares, complemented with data from other instruments (such
  as high-resolution images from TRACE, magnetograms from SOHO/MDI,
  and Yohkoh SXT). We show that CDS provides essential spectroscopic
  information which adds complexity into our understanding of the dynamics
  of solar flares. We give a description of the main observational
  features, and what types of measurements (densities, temperatures,
  flows) are obtained. These observations provide constraints for flare
  modeling, and indications on what types of spectroscopic observations
  future instruments should provide.

Title: CHIANTI -- An Atomic Database for UV and X-ray Cool star
    spectroscopy
Authors: Young, P. R.; Landi, E.; Bromage, G. E.; del Zanna, G.;
   Dere, K. P.; Landini, M.; Mason, H. E.
Bibcode: 2003csss...12.1119Y
Altcode:
  The CHIANTI atomic database was first released in 1996 and has since
  become the standard resource for the interpretation of UV spectra
  from the transition regions and coronae of the Sun and other cool
  stars. We describe the contents of the most recent release (v.3)
  and some of the uses that have been found for the database.

Title: The radiative response of solar loop plasma subject to
    transient heating
Authors: Bradshaw, S. J.; Mason, H. E.
Bibcode: 2003A&A...407.1127B
Altcode:
  In Bradshaw &amp; Mason (\cite{Bradshaw2003}) we carried out a
  hydrodynamic simulation of a cooling solar loop and investigated
  the nonequilibrium response of the population of C VII ions to the
  changing conditions in the plasma. We also compared equilibrium
  and nonequilibrium calculations of the total plasma emissivity. In
  this paper we present two simulations of a solar loop subject to a
  transient heating process delivering energy on the nanoflare scale at
  its apex. One simulation treats the ion populations and the energy
  radiated from the loop plasma entirely as though the system were in
  equilibrium and the other simulation performs a full nonequilibrium
  treatment by coupling the time-dependent ion populations to the
  hydrodynamic equations through the radiative energy loss. Our
  radiative model accounts for the 15 most abundant elements of the
  solar atmosphere including C, O, Ne, Mg, Si and Fe. <P />We find some
  pronounced differences between the populations of certain transition
  region ions and the corresponding plasma emissivity curves in the
  equilibrium and nonequilibrium simulations. Though the apex heating
  event is relatively weak in comparison to energy released on the
  microflare and flare scales, nonetheless a significant amount of energy
  reaches the loop footpoint region to heat the plasma there and we find
  a nonequilibrium spike in emissivity. However, more surprisingly we
  find considerable differences between some of the coronal ions in the
  equilibrium and nonequilibrium simulations, with important consequences
  for the plasma emissivity curves. In particular, we find that the total
  plasma emissivity calculated assuming equilibrium conditions is up to
  a factor of 5 lower than the nonequilibrium emissivity and this is due
  almost entirely to the response of the coronal Fe ions. <P />Finally, we
  suggest possible observational signatures of nonequilibrium ionisation
  and ways in which one might identify it. This is important because
  an invalid assumption of equilibrium ion populations may well lead
  one to incorrect conclusions about the properties of the plasma in
  both a broad-band and narrow-band/emission line based analysis. <P
  />Figures 11 to 13 and Appendix A are only available in electronic
  form at http://www.edpsciences.org

Title: Solar active regions: SOHO/CDS and TRACE observations of
    quiescent coronal loops
Authors: Del Zanna, G.; Mason, H. E.
Bibcode: 2003A&A...406.1089D
Altcode:
  This study focuses on the diagnostic capabilities of the TRACE and
  SOHO-CDS instruments to describe the physical characteristics of
  quiescent solar active regions. In particular we concentrate on
  the 1 MK loops, best seen in the TRACE EUV 173 Å passband. These
  are high-lying structures which can remain stable over timescales
  of hours to days. We present simultaneous observations of off-limb
  active region 1 MK loops performed with TRACE (173 Å and 195 Å
  bands) and the SOHO-CDS. The CDS spectral capabilities complement
  the TRACE observations well and allow an in-depth study of the plasma
  properties. Some important new results are presented here. In terms of
  cross-field characteristics, we find that these loops are isothermal
  and much cooler (T =~ 0.7-1.1 x 10<SUP>6</SUP> K) than the surrounding
  diffuse high-lying active region emission (T =~ 2 x 10<SUP>6</SUP>
  K). We show that the diffuse background-foreground constitutes the
  bulk of the high-lying quiescent active region emission. We explain
  some of the discrepancies found by various authors (based on SOHO
  and TRACE observations) with an overestimation of loop temperatures
  and densities. This was caused by inaccurate or neglected background
  subtraction in the data analysis. We studied the leg of a 1 MK loop and
  found that along its length temperatures and densities have steeper
  profiles compared to those derived from previous studies based on
  TRACE observations. The observations are consistent with an element
  abundance FIP effect of about 4, filling factors close to unity, and
  a constant density across the loop. We find a remarkable consistency
  between the CDS and TRACE observations, although we also find severe
  limitations to the use of TRACE diagnostic techniques.

Title: A self-consistent treatment of radiation   in coronal loop
    modelling
Authors: Bradshaw, S. J.; Mason, H. E.
Bibcode: 2003A&A...401..699B
Altcode:
  We perform a hydrodynamic simulation of a cooling coronal loop and
  calculate the time-dependent ion populations of the most abundant
  elements of the solar atmosphere at each time-step. We couple the
  time-dependent ion balance equations to the hydrodynamic equations in
  order to treat the energy loss through radiation in a self-consistent
  way by allowing for the emission from a potentially nonequilibrium ion
  population. <P />We present results for the response to the changing
  conditions in the loop of the population of C VII ions and find
  significant deviations from equilibrium in the coronal and footpoint
  regions of the loop. The former is due to the tenuous nature of the
  coronal plasma causing recombinations to be rare and the latter is
  due to the strong downflows that develop as the loop cools, which
  carry persistent C VII ions into the lower regions of the loop. We
  also present a comparison between total plasma emissivity curves
  calculated during this simulation and an almost identical simulation
  that assumed an equilibrium ion population for the calculation of the
  radiation term. As a result of the nonequilibrium ion populations
  we find significant differences between the emissivity curves of
  each simulation and the loop cooling times. <P />We suggest that a
  consideration of nonequilibrium ionisation and radiation might help
  to (a) explain the thermal broadening observed in some emission lines
  during explosive events, and (b) reconcile differences between theory
  and observations relating to the longevity of some loops observed in
  the TRACE filters.

Title: Spectroscopic characteristics of polar plumes
Authors: Del Zanna, G.; Bromage, B. J. I.; Mason, H. E.
Bibcode: 2003A&A...398..743D
Altcode:
  Extreme ultraviolet observations of plumes in polar coronal holes are
  presented and their spectroscopic signatures discussed. The study
  focuses on the base of plumes seen on the disk of the Sun with the
  Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric
  Observatory (SOHO) satellite. Spectroscopic diagnostic techniques are
  applied to characterise the plumes in terms of density, temperature,
  emission measure and element abundance. Attention is drawn to the
  particular limitations of some of the techniques when applied to plume
  structures. In particular, we revisit the Widing &amp; Feldman (1992)
  findings of a plume having a large first ionization potential (FIP)
  effect of 10, showing that instead the Skylab data are consistent
  with no FIP effect. We present for the first time CDS-GIS (grazing
  incidence spectrometer) observations of a plume. These observations
  have been used to confirm the results obtained from normal incidence
  (NIS) observations. We find that polar plumes exhibit the same
  characteristics as the Elephant's Trunk equatorial plume. The
  most striking characteristic of the plume bases is that they are
  near-isothermal with a peak emission measure at transition region
  temperatures =~ 8 x 10<SUP>5</SUP> K. At these temperatures, plumes have
  averaged densities Nlo {e} =~ 1.2 x 10<SUP>9</SUP> cm<SUP>-3</SUP>,
  about twice the value of the surrounding coronal hole region. Element
  abundances in the plumes are found to be close to photospheric, with the
  exception of neon which appears to be depleted by 0.2 dex relative to
  oxygen. The absence of a significant FIP effect in plumes is consistent
  with fast solar wind plasma, although it is not sufficient to prove
  a link between the two. Finally, we present a comparison between GIS
  spectra and the SOHO EIT (EUV Imaging Telescope) broad-band images,
  showing that temperatures derived from the EIT ratio technique are
  largely overestimated, for plumes and coronal holes. This is partly
  due to the fact that the so called ``Fe XII 195 Å'' and ``Fe XV
  284 Å'' filters are not isothermal, and in coronal holes and plumes
  lower-temperature lines dominate the EIT signal.

Title: CHIANTI-An Atomic Database for Emission Lines. VI. Proton
    Rates and Other Improvements
Authors: Young, P. R.; Del Zanna, G.; Landi, E.; Dere, K. P.; Mason,
   H. E.; Landini, M.
Bibcode: 2003ApJS..144..135Y
Altcode: 2002astro.ph..9493Y
  The CHIANTI atomic database contains atomic energy levels, wavelengths,
  radiative transition probabilities, and electron excitation data for
  a large number of ions of astrophysical interest. Version 4 has been
  released, and proton excitation data are now included, principally
  for ground configuration levels that are close in energy. The fitting
  procedure for excitation data, both electrons and protons, has been
  extended to allow nine-point spline fits in addition to the previous
  five-point spline fits. This allows higher quality fits to data from
  close-coupling calculations where resonances can lead to significant
  structure in the Maxwellian-averaged collision strengths. The effects
  of photoexcitation and stimulated emission by a blackbody radiation
  field in a spherical geometry on the level balance equations of
  the CHIANTI ions can now be studied following modifications to the
  CHIANTI software. With the addition of H I, He I, and N I, the first
  neutral species have been added to CHIANTI. Many updates to existing
  ion data sets are described, while several new ions have been added
  to the database, including Ar IV, Fe VI, and Ni XXI. The two-photon
  continuum is now included in the spectral synthesis routines, and a
  new code for calculating the relativistic free-free continuum has been
  added. The treatment of the free-bound continuum has also been updated.

Title: CHIANTI - An Atomic Database for XUV Emission Lines
Authors: Landi, Enrico; Dere, Ken P.; Landini, Massimo; Young, Peter
   R.; Mason, Helen E.; del Zanna, Giulio
Bibcode: 2003IAUJD..17E..10L
Altcode:
  CHIANTI is a database of atomic data and transition rates necessary for
  calculating synthetic spectra and carrying out plasma diagnostics of
  astrophysical sources in the X-ray EUV and UV wavelength ranges. CHIANTI
  includes both line and continuum emission from all astrophysically
  abundant elements in the universe. All data are taken from refereed
  literature and are critically assessed. CHIANTI also includes a suite
  of IDL programs that allow spectroscopic analysis to be carried
  out. CHIANTI data and software are freely distributed over the
  internet. <P />In the present talk I will describe the contents of
  the CHIANTI database its current status and the areas where CHIANTI
  is being developed and I will also present a comparison of CHIANTI
  predictions with the X-ray emission from astrophysical sources.

Title: Active Region Studies with SOHO-CDS
Authors: Mason, H. E.; Del Zanna, G.
Bibcode: 2002ASPC..277...37M
Altcode: 2002sccx.conf...37M
  No abstract at ADS

Title: EUV spectral observations of active region flares
Authors: Del Zanna, G.; Mason, H. E.; Foley, C.
Bibcode: 2002ESASP.506..585D
Altcode: 2002svco.conf..585D; 2002ESPM...10..585D
  We present EUV spectral observations of C-M class flares performed
  with the Coronal Diagnostic Spectrometer (CDS) onboard SOHO during the
  Cambridge active region (AR) campaigns in 1999 and 2001. With the CDS
  spectral data, complemented by other space observations (mainly TRACE,
  YOHKOH SXT), we investigate the physical properties of ARs, and study
  the development of small-scale flares. We discuss the importance of
  spectral observations in relation to the correct interpretation of
  broad band images. In particular, we present co-spatial simultaneous
  YOHKOH SXT and CDS flare observations and discuss the validity of the
  temperatures derived from the SXT filter ratios. In addition, we present
  sample results that can only be obtained with spectral data, such as
  measurements of densities, elemental abundances and post-flare flows,
  associated with slow chromospheric evaporation. All these results are
  important observational constraints for flare modeling.

Title: Solar and stellar high-resolution X-ray spectra: plasma
    diagnostics with the CHIANTI atomic database
Authors: Del Zanna, G.; Mason, H. E.
Bibcode: 2002ASPC..277..333D
Altcode: 2002sccx.conf..333D
  No abstract at ADS

Title: The Structure and Evolution of a Sigmoidal Active Region
Authors: Gibson, S. E.; Fletcher, L.; Del Zanna, G.; Pike, C. D.;
   Mason, H. E.; Mandrini, C. H.; Démoulin, P.; Gilbert, H.; Burkepile,
   J.; Holzer, T.; Alexander, D.; Liu, Y.; Nitta, N.; Qiu, J.; Schmieder,
   B.; Thompson, B. J.
Bibcode: 2002ApJ...574.1021G
Altcode:
  Solar coronal sigmoidal active regions have been shown to be precursors
  to some coronal mass ejections. Sigmoids, or S-shaped structures,
  may be indicators of twisted or helical magnetic structures, having
  an increased likelihood of eruption. We present here an analysis of a
  sigmoidal region's three-dimensional structure and how it evolves in
  relation to its eruptive dynamics. We use data taken during a recent
  study of a sigmoidal active region passing across the solar disk
  (an element of the third Whole Sun Month campaign). While S-shaped
  structures are generally observed in soft X-ray (SXR) emission, the
  observations that we present demonstrate their visibility at a range of
  wavelengths including those showing an associated sigmoidal filament. We
  examine the relationship between the S-shaped structures seen in SXR
  and those seen in cooler lines in order to probe the sigmoidal region's
  three-dimensional density and temperature structure. We also consider
  magnetic field observations and extrapolations in relation to these
  coronal structures. We present an interpretation of the disk passage
  of the sigmoidal region, in terms of a twisted magnetic flux rope
  that emerges into and equilibrates with overlying coronal magnetic
  field structures, which explains many of the key observed aspects of
  the region's structure and evolution. In particular, the evolving flux
  rope interpretation provides insight into why and how the region moves
  between active and quiescent phases, how the region's sigmoidicity is
  maintained during its evolution, and under what circumstances sigmoidal
  structures are apparent at a range of wavelengths.

Title: Spectroscopic diagnostics of stellar transition regions and
coronae in the XUV: AU Mic in quiescence
Authors: Del Zanna, G.; Landini, M.; Mason, H. E.
Bibcode: 2002A&A...385..968D
Altcode:
  In this paper we review the spectroscopic diagnostic techniques that
  can be applied to XUV observations of active stars. In particular, we
  discuss methods for the determination of electron densities, emission
  measures and the chemical composition of the stellar transition regions
  and coronae. We pay particular attention to the atomic data used and
  we revise several previous analyses with the most recent atomic data
  (from CHIANTI). We find severe limitations to some of the commonly used
  methods and atomic data and we obtain results which are significantly
  different from other authors. We illustrate this with a number of
  examples. We analyse a combined set of multi-wavelength observations
  (EUVE, HST/STIS, FUSE) for the quiescent phase of the dMe star AU Mic. A
  major conclusion of this paper is that the use of spectral lines from
  the Li and Na isoelectronic sequences, common in previous literature,
  produces erroneous results in the determination of emission measures,
  elemental abundances and transition region densities.

Title: EUV Spectroscopic Observations of Spray Ejecta from an X2 Flare
Authors: Pike, C. D.; Mason, H. E.
Bibcode: 2002SoPh..206..359P
Altcode:
  An X2.3 class flare was reported on 10 April 2001 in AR 9415. A halo
  coronal mass ejection (CME) was associated with this flare. The Coronal
  Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric
  Observatory (SOHO), which was running in its daily synoptic mode,
  recorded a very high-velocity ejection of plasma associated with
  this activity. The spatial scanning and spectral capabilities
  of CDS allow the measurement of both transverse and line-of-sight
  velocities. Components of the plasma, as seen in emission from O v at
  around 2.5×10<SUP>5</SUP> K, reached transverse velocities in excess
  of 800 km s<SUP>−1</SUP>. The nature of the spectral line profiles
  suggests that a rotational motion of ± 350 km s<SUP>−1</SUP> was
  superimposed upon the general outward expansion of approximately 150
  km s<SUP>−1</SUP>. The ejection detected using CDS was found to have
  a constant acceleration and is thought to be a spray of plasma with
  a helical structure driven by the magnetic topology.

Title: SOHO-CDS Observations of an X2 Flare Spray Injection
Authors: Mason, H. E.; Pike, C. D.
Bibcode: 2002mwoc.conf...89M
Altcode:
  Spectral observations with SOHO-CDS provide an opportunity to study the
  development of active region structures. In particular, it is possible
  to determine the plasma properties: temperature and electron density
  distribution, elemental abundances and mass motions. The nature of
  enhancements in the transition region emission is investigated.

Title: Sigmoidal diagnostics with SOHO/CDS
Authors: Del Zanna, G.; Gibson, S. E.; Mason, H. E.; Pike, C. D.;
   Mandrini, C. H.
Bibcode: 2002AdSpR..30..551D
Altcode:
  During the third Whole Sun Month Campaign (August 18 - September 14,
  1999), the evolution of the active region NOAA 8668 was followed
  during its meridian passage and at the limb (Sigmoid JOP 106),
  with simultaneous observations with the Solar and Heliospheric
  Observatory (SOHO), and with other instruments, both satellite
  and ground-based. On August 21st, a small flare, associated with
  a brightening of the sigmoidal structure, occurred. SOHO Coronal
  Diagnostic Spectrometer (CDS) observations of this small flare are
  presented. Coronal temperatures and densities of the sigmoid are
  estimated. High transition region densities (in the range 2.5-7 × 10
  <SUP>11</SUP> cm <SUP>-3</SUP>), obtained using O IV, are present in
  the brightenings associated with the flare. At coronal level, high
  temperatures of at least 8 MK were reached, as shown by strong Fe
  XIX emission. After this small flare, relatively strong blue-shifts
  (⋍ 30 km/s) are observed in coronal lines, located at the two ends
  of a small loop system associated with the sigmoid.

Title: The CHIANTI Atomic Database and Instrument Calibration:
    a Symbiosis
Authors: Mason, H. E.; Del Zanna, G.; Dere, K. P.; Landi, E.; Landini,
   M.; Young, P. R.
Bibcode: 2002ISSIR...2..271M
Altcode: 2002ESASR...2..271M; 2002rcs..conf..271M
  The CHIANTI atomic database comprises a comprehensive, accurate and
  up-to-date database of atomic parameters, necessary for emission-line
  spectroscopy. The suite of user-friendly software allows plasma
  diagnostics to be carried out. Since its release in 1996, CHIANTI has
  become a standard resource for the analysis of solar spectra. Accurate
  atomic data can provide the foundation for in-flight instrument
  calibrations. Conversely, an accurate instrument calibration can provide
  a check on atomic parameters. The internal consistency of spectral-line
  intensities can be used to highlight specific anomalies. In this paper,
  we illustrate how CHIANTI has been used to validate the calibration of
  solar EUV instruments: SOHO-CDS, -SUMER, -EIT and SERTS. In addition,
  we show how anomalous spectral-line intensities indicate the need for
  more accurate atomic calculations.

Title: A Relationship Between Transition Region Brightenings,
    Abundances, and Magnetic Topology
Authors: Fletcher, Lyndsay; López Fuentes, Marcelo C.; Mandrini,
   Cristina H.; Schmieder, Brigitte; Démoulin, Pascal; Mason, Helen E.;
   Young, Peter R.; Nitta, Nariaki
Bibcode: 2001SoPh..203..255F
Altcode:
  We present multi-instrument observations of active region (AR) 8048,
  made between 3 June and 5 June 1997, as part of the SOHO Joint Observing
  Program 33. This AR has a sigmoid-like global shape and undergoes
  transient brightenings in both soft X-rays and transition region
  (TR) lines. We compute a magneto-hydrostatic model of the AR magnetic
  field, using as boundary condition the photospheric observations of
  SOHO/MDI. The computed large-scale magnetic field lines show that the
  large-scale sigmoid is formed by two sets of coronal loops. Shorter
  loops, associated with the core of the SXT emission, coincide with
  the loops observed in the hotter CDS lines. These loops reveal a
  gradient of temperature, from 2 MK at the top to 1 MK at the ends. The
  field lines most closely matching these hot loops extend along the
  quasi-separatrix layers (QSLs) of the computed coronal field. The TR
  brightenings observed with SOHO/CDS can also be associated with the
  magnetic field topology, both QSL intersections with the photosphere,
  and places where separatrices issuing from bald patches (sites where
  field lines coming from the corona are tangent to the photosphere)
  intersect the photosphere. There are, furthermore, suggestions that
  the element abundances measured in the TR may depend on the type
  of topological structure present. Typically, the TR brightenings
  associated with QSLs have coronal abundances, while those associated
  with BP separatrices have abundances closer to photospheric values. We
  suggest that this difference is due to the location and manner in which
  magnetic reconnection occurs in two different topological structures.

Title: Elemental abundances of the low corona as derived from
    SOHO/CDS observations
Authors: Del Zanna, G.; Bromage, B. J. I.; Mason, H. E.
Bibcode: 2001AIPC..598...59D
Altcode: 2001sgc..conf...59D
  No abstract at ADS

Title: A comparison between theoretical and solar FeXII UV line
    intensity ratios UV line intensity ratios
Authors: Binello, A. M.; Landi, E.; Mason, H. E.; Storey, P. J.;
   Brosius, J. W.
Bibcode: 2001A&A...370.1071B
Altcode:
  A new set of radiative and electron collisional data for Fe XII
  was presented in two earlier papers. In the present work, we derive
  level populations and theoretical line intensities for a range of
  plasma densities and temperatures. Observations of Fe XII lines
  obtained with the Solar EUV Rocket Telescope and Spectrograph are
  analysed both as a check the quality of the new atomic data and
  to determine the electron density in active regions and the quiet
  Sun. The discrepancy between the electron density values determined
  from Fexii line intensity ratios and those obtained from other ions
  is investigated. Tables 2-5 are also available in electronic form
  at the CDS via anonymous ftp to cdarc.u-strasbg.fr (130.79.128.5)
  or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/370/1071}

Title: VizieR Online Data Catalog: Fe XII UV line intensity ratios
    (Binello+, 2001)
Authors: Binello, A. M.; Landi, E.; Mason, H. E.; Storey, P. J.;
   Brosius, J. W.
Bibcode: 2001yCat..33701071B
Altcode:
  A new set of radiative and electron collisional data for Fe XII
  was presented in two earlier papers. In the present work, we derive
  level populations and theoretical line intensities for a range of
  plasma densities and temperatures. Observations of Fe XII lines
  obtained with the Solar EUV Rocket Telescope and Spectrograph are
  analysed both as a check on the quality of the new atomic data and
  to determine the electron density in active regions and the quiet
  Sun. The discrepancy between the electron density values determined
  from Fe XII line intensity ratios and those obtained from other ions
  is investigated. (2 data files).

Title: CDS UV Brightenings Explained by Quasi-separatrices and Bald
    Patches in an S-shape active region
Authors: Schmieder, B.; Démoulin, P.; Fletcher, L.; López Fuentes,
   M. C.; Mandrini, C. H.; Mason, H. E.; Young, P. R.; Nitta, N.
Bibcode: 2001IAUS..203..314S
Altcode:
  We present multi-instrument observations of AR 8048, made between
  June 3 and June5 1997 as part of SoHO JOP033. This active region
  has a sigmoid-like global shape and undergoes transient erupting
  phenomena which releases the stored energy. Using a force free
  field approach, we defined coronal magnetic field lines which fit
  with the observations. The large-scale magnetic field lines confirms
  the sigmoid characteristics of the active region. The study in 3D of
  the configuration explained where and how the energy is released at
  different places. The Ne VI brightenings correspond to the location
  of tangent to the photosphere field lines, named "bald patch", they
  are localized in the low transition region and represent feet of field
  lines. The Si XII brightenings at coronal temperature are at the top
  of coronal loops joining quasi-separatrices.

Title: Solar Spectroscopy and Diagnostics
Authors: Mason, H.
Bibcode: 2000eaa..bookE1985M
Altcode:
  Solar spectroscopy and diagnostics provide the opportunity for
  determining the physical parameters in different parts of the solar
  atmosphere....

Title: Solar Spectroscopy: Atomic Processes
Authors: Mason, H.
Bibcode: 2000eaa..bookE2229M
Altcode:
  A Greek philosopher called DEMOCRITUS (c. 460-370 BC) first introduced
  the concept of atoms (which means indivisible). His atoms do not
  precisely correspond to our atoms of today, which are not indivisible,
  but made up of a nucleus (protons with positive charge and neutrons
  which have no charge) and orbiting electrons (with negative
  charge). Indeed, in the solar atmosphere, the temperature is suc...

Title: Seeking the magnetic roots of a sample of SOHO coronal
    bright points.
Authors: Saba, J. L. R.; Zamkoff, E. B.; Mason, H. E.; Pike, C. D.;
   Moses, J. D.; Covington, J. F.
Bibcode: 2000BAAS...32..808S
Altcode:
  No abstract at ADS

Title: SUMER observations of transition region fine structures
Authors: Landi, E.; Mason, H. E.; Lemaire, P.; Landini, M.
Bibcode: 2000A&A...357..743L
Altcode:
  The SUMER (Solar Ultraviolet Measurements of Emitted Radiation)
  instrument on SOHO (Solar and Heliospheric Observatory) provides an
  opportunity to observe and study the solar transition region with
  high spatial and spectral resolution. We present new evidence to
  confirm that the emission from the quiet Sun at 2x 10<SUP>5</SUP> K
  is dominated by cool loop-like fine structures which cluster across
  the chromospheric network boundaries. The electron density of these
  structures is found to be around 10<SUP>10</SUP> cm<SUP>-3</SUP>. The
  red-shifts in spectral line profiles and the non-thermal widths from
  lines formed at this temperature are found to be correlated with
  intensity. The properties of explosive events with irregular profiles
  are explored. A large jet-like structure is analysed. The results of
  our analysis are compared with recent predictions from numerical models.

Title: Seeking the Magnetic Roots of a Sample of SOHO Coronal
    Bright Points
Authors: Saba, J. L. R.; Zamkoff, E. B.; Mason, H. E.; Pike, C. D.;
   Moses, J. D.; Covington, J. F.
Bibcode: 2000SPD....31.0143S
Altcode:
  As part of an ongoing study of X-ray/EUV bright points (XBPs)
  in synoptic data from the Coronal Diagnostic Spectrometer (CDS)
  on the Solar and Heliospheric Observatory (SoHO), we consider six
  CDS XBP detections for which there are concurrent high-cadence,
  high-spatial-resolution magnetogram data from the SoHO Michelson Doppler
  Imager (MDI). All six cases occurred at solar minimum or in the early
  rise phase of solar cycle 23 (Jul 1996 - Jan 1998). They sample a factor
  of 10 range in size of XBPs as detected by CDS in an Fe XVI coronal
  emission line, with peak formation temperature of about 2.5 MK. MDI
  data are available for over 1.5 hr leading up to each CDS observation,
  and for at least 0.4 hr after; this allows a detailed study of the
  magnetic field evolution under the XBP site, including detection of flux
  emergence or cancellation. EIT data are used to monitor the evolution
  and persistence of these XBPs in the corona before and after the CDS
  detections. The nature of the jointly observed XBPs is investigated,
  in particular the relationship of the plasma parameters and size found
  with CDS, and the timescales for coronal evolution inferred from EIT,
  to the character of the underlying magnetic field and its changes
  as observed with MDI. This work was supported by the SOI/MDI project
  at Stanford and LMSAL (grant NAG5-3077). HEM and CDP acknowledge the
  financial support of PPARC.

Title: SunBlock '99- An Educational Resource
Authors: Pike, C. D.; Mason, H. E.; Walsh, R. W.
Bibcode: 2000ASPC..205..141P
Altcode: 2000ltse.conf..141P
  SunBlock `99 is a web-based Public Understanding of Science and
  educational project which presents the very latest solar research as
  seen through the eyes of young British scientists. It seeks both to
  increase public awareness of solar physics and to provide an educational
  resource for use in the classroom.

Title: Dynamics in Restructuring Active Regions Observed During
    Soho/Yohkoh/Gbo Campaigns
Authors: Schmieder, B.; Deng, Y.; Mandrini, C. H.; Rudawy, P.; Nitta,
   N.; Mason, H.; Fletcher, L.; Martens, P.; Brynildsen, N.
Bibcode: 2000AdSpR..25.1879S
Altcode:
  JOP17 and JOP 33 are SOHO Joint Observing Programs in collaboration
  with Yohkoh/SXT and ground based observatories (GBO's), dedicated to
  observe dynamical events through the atmosphere. During runs of these
  programs we observed in restructuring active regions (ARs), surges,
  subflares, bright knots, but not large flares and jets. From these
  observations we have been able to derive some of the responses of the
  coronal and chromospheric plasma to the evolution of the photospheric
  magnetic field. Emerging flux in an AR led to the formation of Arch
  Filament Systems in the chromosphere, hot loops and knots in the
  transition region, and X-ray loops. Frequent surges have been observed
  in relation to parasitic or mixed polarities, but coronal jets have not
  yet been found. We discuss the possible mechanisms acting during the
  restructuring of the active regions (reconnection or ``sea-serpent''
  geometries)

Title: Atomic data from the IRON Project. XL. Electron impact
    excitation of the Fe XIV EUV transitions
Authors: Storey, P. J.; Mason, H. E.; Young, P. R.
Bibcode: 2000A&AS..141..285S
Altcode:
  We calculate collision strengths and thermally averaged collision
  strengths for electron excitation between the forty energetically
  lowest levels of Fe<SUP>13+</SUP>. The scattering calculation is more
  complete than any previous work on this ion and significant differences
  are found in the excitation rates for many of the extreme ultra-violet
  (EUV) transitions, compared to earlier work. A detailed comparison
  is made between predicted line intensity ratios and those observed in
  solar coronal spectra which shows that several outstanding discrepancies
  are resolved by the new atomic data.

Title: Commission 14: Atomic and Molecular Data: (Donnees Atomiques
    et Moleculaires)
Authors: Rostas, F.; Smith, P. L.; Berrington, K. A.; Feautrier, N.;
   Grevesse, N.; Johansson, S.; Jørgensen, U. G.; Martin, W. C.; Mason,
   H.; Parkinson, W.; Tchang-Brillet, W. -Ü. L.
Bibcode: 2000IAUTA..24..380R
Altcode:
  No abstract at ADS

Title: CHIANTI: A database for astrophysical emission line
    spectroscopy
Authors: Del-Zanna, Giulio; Young, Peter; Dere, Ken; Landini, Massimo;
   Landi, Enrico; Mason, Helen
Bibcode: 1999ascl.soft11004D
Altcode:
  CHIANTI consists of a critically evaluated set of atomic data necessary
  to calculate the emission line spectrum of astrophysical plasmas. The
  data consists of atomic energy levels, atomic radiative data such as
  wavelengths, weighted oscillator strengths and A values, and electron
  collisional excitation rates. A set of programs that use these data to
  calculate the spectrum in a desired wavelength range as a function of
  temperature and density are also provided. These programs have been
  written in Interactive Data Language (IDL) and descriptions of these
  various programs are provided on the website.

Title: Temperature and density in a polar plume - measurements
    from CDS/SOHO
Authors: Young, P. R.; Klimchuk, J. A.; Mason, H. E.
Bibcode: 1999A&A...350..286Y
Altcode:
  A detailed analysis of a particularly intense polar plume observed
  on the 25th of October, 1996, by the Coronal Diagnostic Spectrometer
  (CDS) on board the Solar and Heliospheric Observatory (SOHO) is
  presented. Above the limb, emission measure distributions derived for
  both the plume and a section of coronal hole background are found to
  be sharply peaked at approximately 1.0-1.1 million degrees in both
  regions. The temperature rises with height in the background, but no
  evidence is found for a rising temperature in the plume. The density
  of the background is approximately 10(8) electrons/cm(3) and falls
  with height. In the plume the density is between 3.8 and 9.5x 10(8)
  electrons/cm(3) , and exhibits no decrease with height up to 70 000
  km. The plume base is visible on the solar surface and shows a strong
  brightening lying directly below the main body of the plume. This
  brightening has a temperature of 2 000 000 K, and a density of
  2.5-5.6x 10(9) electrons/cm(3) . Images from lines formed at different
  temperatures suggest that the morphology of the base is consistent with
  an emerged bipole in a region of unipolar magnetic flux. A measurement
  of the Mg/Ne relative abundance is made at two transition region
  brightenings at the base of the plume. An enhancement of only 1.5 is
  found over the photospheric value. Considerations of the geometry of
  both the high temperature brightening at the base of the plume and
  the off-limb section give filling factors of 0.5 and 1.0, respectively.

Title: Variation of Thermal Structure with Height of a Solar Active
    Region Derived from SOHO CDS and YOHKOH BCS Observations
Authors: Sterling, Alphonse C.; Pike, C. D.; Mason, Helen E.; Watanabe,
   Tetsuya; Antiochos, Spiro K.
Bibcode: 1999ApJ...524.1096S
Altcode:
  We present observations of NOAA solar Active Region 7999 when it was
  near the west solar limb on 1996 December 2 and 3, using data from
  the Coronal Diagnostic Spectrometer (CDS) experiment on the SOHO
  satellite. Ratios of intensities of 2 MK material (as observed in
  CDS Fe XVI images) to 1 MK material (from CDS Mg IX images) indicate
  that there is a drop in the ratio of the hotter to the cooler material
  with height in the region, up to an altitude of about 10<SUP>5</SUP>
  km. At low altitudes the relative amount of 2 MK emission measure to
  1 MK emission measure ranges from 8 to 10, while the ratio is minimum
  near 10<SUP>5</SUP> km, ranging from 1.3 to 3.5. The decrease with
  height of the CDS ratio qualitatively resembles the decrease in S
  XV election temperature with height (measurable up to ~85,000 km) in
  the same active region obtained from the Bragg crystal spectrometer
  instrument on Yohkoh. The CDS images indicate that the highest S
  XV temperatures and largest CDS ratios correspond to regions of
  microflares, and somewhat lower S XV temperatures and CDS ratios
  correspond to diffuse regions. Above 10<SUP>5</SUP> km, the trend of
  the CDS ratios changes, either increasing or remaining approximately
  constant with height. At these altitudes the CDS images show faint,
  large-scale diffuse structures.

Title: SunBlock '99: Young Scientists Investigate the Sun
Authors: Walsh, R. W.; Pike, C. D.; Mason, H.; Young, P.; Ireland,
   J.; Galsgaard, K.
Bibcode: 1999ESASP.446..693W
Altcode: 1999soho....8..693W
  SunBlock `99 is a Web-based Public Understanding of Science and
  educational project which seeks to present the very latest solar
  research as seen through the eyes of young British scientists. These
  ``solar guides'' discuss not only their scientific interests, but also
  their extra-curricular activities and the reasons they chose scientific
  careers; in other words the human face of scientific research. The
  SunBlock '99 pages gather a range of solar images and movies from
  current solar space observatories and discuss the underlying physics
  and its relationship to the school curriculum. The instructional level
  is pitched at UK secondary school children (aged 13-16 years). It is
  intended that the material should not only provide a visually appealing
  introduction to the study of the Sun, but that it should help bridge
  the often wide gap between classroom science lessons and the research
  scientist `out in the field'. SunBlock '99 is managed by a team from
  the Rutherford Appleton Laboratory and the Universities of St Andrews
  and Cambridge, together with educational consultants. The production
  has, in part, been sponsored by PPARC and the Millennium Mathematics
  Project. Web site addresss: http://www.sunblock99.org.uk

Title: Searching for Sigmoids in SOHO/CDS
Authors: Gibson, Sarah; Mason, Helen; Pike, Dave; Young, Peter
Bibcode: 1999ESASP.446..331G
Altcode: 1999soho....8..331G
  Sigmoidal structures observed in X-rays have been shown to be precursors
  to CMEs, existing in some cases for several days before an eruption
  (Sterling and Hudson 1997,ApJ,491,L55; Canfield et al, 1999, GRL, 26,
  6, 627). While these S-shaped structures are most apparent in X-ray
  active region observations, they may be manifestations of a more general
  helical magnetic structure having observational signatures at other
  wavelengths. We will present preliminary results of a survey search for
  sigmoidal structures and other CME tracers in archived SOHO/CDS data
  for a series of active regions known to contain erupting sigmoidal
  structures in X-ray observations. We are particularly interested in
  determining the relative locations and temperatures of these tracers,
  and will see to what extent the data answers questions such as,
  if S shapes are observed at different wavelengths do they line up,
  or is there a spatial displacement and/or rotation of angle of S that
  corresponds with height/temperature variation ? How does the appearance
  of the region vary over the lifetime of the observed x-ray sigmoidal
  structure ? After an eruption, how much if any of the S shape remains,
  and at what spatial and spectral locations ? We will use the results of
  this comparison survey to consider what the implications are for the
  underlying magnetic field structure, and the location and variation
  of heating throughout it.

Title: Electron density and temperature structure of two limb active
    regions observed by SOHO-CDS
Authors: Mason, H. E.; Landi, E.; Pike, C. D.; Young, P. R.
Bibcode: 1999SoPh..189..129M
Altcode:
  The analysis of two active regions on the limb using observations from
  SOHO-CDS allows us to determine the electron density and temperature
  distribution of the coronal emission. We find that the active regions
  have hot cores (3×10<SUP>6</SUP> K) with larger cooler (10<SUP>6</SUP>
  K) loop structures extending above the limb. The electron number
  density, determined using the Si X diagnostic line ratio, is found to
  be highest in the active region core (greater than 2.3×10<SUP>9</SUP>
  cm<SUP>−3</SUP>). Electron number density values are determined for a
  range of spectral lines from different ions and are found to increase
  with temperature between 0.8 and 2.5×10<SUP>6</SUP> K. These results
  are consistent with recent models of enhanced heating along the compact
  core of active regions, where the magnetic field shear is strongest.

Title: CHIANTI - an atomic database for emission lines. III. Continuum
    radiation and extension of the ion database
Authors: Landi, E.; Landini, M.; Dere, K. P.; Young, P. R.; Mason,
   H. E.
Bibcode: 1999A&AS..135..339L
Altcode:
  CHIANTI provides a database of atomic energy levels, wavelengths,
  radiative transition probabilities and electron excitation data for a
  large number of ions of astrophysical interest. This database allows
  the calculation of theoretical line emissivities necessary for the
  analysis of optically thin emission line spectra, and includes also
  a suite of IDL (Interactive Data Language) programs to calculate
  optically thin synthetic spectra and to perform spectral analysis and
  plasma diagnostics. The first version (1.0) of the CHIANTI database was
  released in 1996 te[(Dere et al. 1997)]{Der97} and has been extensively
  used for analysis of line spectra from astrophysical sources by the
  scientific community. The present paper describes the first major update
  to the CHIANTI database which will subsequently be labeled version
  2.0. The update consists of the addition of a large number of new ions,
  the revision of existing data for some ions and the inclusion of an
  IDL procedure to calculate the continuum. The CHIANTI atomic database
  and supporting IDL routines are freely available through the internet.

Title: Solar Wind Outflow and the Chromospheric Magnetic Network
Authors: Hassler, Donald M.; Dammasch, Ingolf E.; Lemaire, Philippe;
   Brekke, Pal; Curdt, Werner; Mason, Helen E.; Vial, Jean-Claude;
   Wilhelm, Klaus
Bibcode: 1999Sci...283..810H
Altcode:
  No abstract at ADS

Title: Calentamiento de arcos coronales en una región activa por
    reconfiguración topológica del campo magnético.
Authors: López Fuentes, M.; Mandrini, C. H.; Démoulin, P.; Schmieder,
   B.; Fletcher, L.; Mason, H.
Bibcode: 1999BAAA...43...24L
Altcode:
  We study the active region (AR) 8048 observed on June 1997 in several
  wavelenghts. The combined observations obtained using CDS (SOHO)
  and SXT (Yohkoh) show the heating of the coronal magnetic loops at
  different atmospheric altitudes. Extrapolating the magnetic field in the
  corona from longitudinal magnetograms from MDI (SOHO), we determine the
  location of Bald Patches in the surroundings of the leading spot. This
  magnetic feature, the emergence of parasitic magnetic polarities and
  the observed photospheric motions provide the conditions to explain
  the observed heating.

Title: SOHO - Where has the Quiet Sun gone?
Authors: Mason, H. E.
Bibcode: 1999ASPC..158..348M
Altcode: 1999ssa..conf..348M
  No abstract at ADS

Title: Working Group 4 Report: Composition and Elemental Abundance
    Variations in the Solar Atmosphere and Solar Wind
Authors: Mason, Helen E.; Bochsler, Peter
Bibcode: 1999SSRv...87..105M
Altcode:
  This paper contains a summary of the topics treated in the working
  group on abundance variations in the solar atmosphere and in the solar
  wind. The FIP bias (overabundance of particles with low First Ionization
  Potentials over photospheric abundances) in coronal holes and coronal
  hole associated solar wind amounts to values between 1 and 2. The FIP
  bias in the slow solar wind is typically a factor 4, consistent with
  optical observations in streamers. In order to distinguish between
  different theoretical models which make an attempt to explain the FIP
  bias, some observable parameters must be provided. Unfortunately,
  many models are deficient in this respect. In addition to FIP
  fractionation, gravitational settling of heavy elements has been
  found in the core of long lived streamers. The so-called electron
  'freeze in' temperatures derived from in situ observed ionization
  states of minor ions in the fast wind are significantly higher than
  the electron temperatures derived from diagnostic line ratios observed
  in polar coronal holes. The distinction between conditions in plumes
  and interplume lanes needs to be further investigated. The 'freeze in'
  temperatures for the slow solar wind are consistent with the electron
  temperatures derived for streamers.

Title: Observation of Transition Region Fine Structures with
    Soho/Sumer
Authors: Landi, E.; Mason, H. E.; Landini, M.
Bibcode: 1999SSRv...87..241L
Altcode:
  We present a preliminary analysis of two quiet Sun transition
  region areas observed with the SOHO/SUMER spectrometer, using lines
  from oxygen, nitrogen and silicon. The average quiet Sun physical
  parameters are studied as a function of line intensity. Systematic
  variations of line position and width with increasing intensity are
  found. A large number of small-scale active points have been observed,
  and preliminary analysis of the physical properties and dynamics of
  these active features is presented. A jet-like structure, found in an
  active point, is also investigated and its velocity along the line of
  sight determined.

Title: Rotating Transition Region Features Observed with the SOHO
    Coronal Diagnostic Spectrometer
Authors: Pike, C. D.; Mason, H. E.
Bibcode: 1998SoPh..182..333P
Altcode:
  Strong evidence has been found from SOHO-CDS (Solar and Heliospheric
  Observatory - Coronal Diagnostic Spectrometer) observations to support
  the hypothesis that rotation plays a major role in the dynamics of
  transition region features. A comprehensive survey of the CDS daily
  synoptic rasters has been carried out to select dynamic events by
  searching for spectral line shifts in the O v emission line at 629.73 Å
  (formed at a temperature of 2.5×105 K). Unique CDS observations of a
  macrospicule were reported by Pike and Harrison (1997), and several more
  macrospicule-like solar features have now been identified in the polar
  regions both on the limb and disk. These show blue- and red-shifted
  emission on either side of an axis stretching above the limb from
  a footpoint region on the disk. These observations are interpreted
  as indicating the presence of a rotating plasma, a sort of solar
  tornado. In the examples studied, the rotation velocities increase
  with height. The implications for coronal heating models are discussed.

Title: Atomic data from the IRON project. XXXI. Electron impact
    excitation of optically allowed and intercombination electric dipole
    transitions in Fe XII
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
Bibcode: 1998A&AS..131..153B
Altcode:
  A new, accurate set of electron impact collisional data is presented,
  relating to all electric dipole fine-structure transitions between
  the ground {3s(2) 3p(3) } and the first two excited {3s 3p(4) },
  {3s(2) 3p(2) 3d} configurations in {Fe xii} (Fe(11+) ). Theoretical
  energies have been obtained with a multi-configuration atomic structure
  calculation. The {R-matrix} method, coupled with the {Coulomb-Bethe}
  (CBe) approximation for the high partial wave contributions to the
  collision strengths, has been employed in the Fe(11+) - e(-) scattering
  problem. The data presented in this paper form part of the IRON Project
  effort to provide the most accurate atomic data available to date
  for all the iron ions (Hummer et al. 1993). Tables 1 to 9 are also
  available in electronic form at the CDS via ftp to cdsarc.u-strasbg.fr
  (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Title: A new perspective on the sun from SOHO-challenges for atomic
    physics
Authors: Dere, Kenneth; Mason, Helen
Bibcode: 1998AIPC..434..213D
Altcode: 1998amda.conf..213D
  The Solar and Heliospheric Observatory (SOHO) carries several
  ultraviolet spectrometers to diagnose the plasma conditions of
  the solar atmosphere in order to address several outstanding
  questions in solar research: why is the corona hot and how is the
  solar wind accelerated. Diagnostic techniques for determining the
  magnetohydrodynamic state (magnetic field, density, temperature,
  velocity) are discussed. We describe the CHIANTI database which has been
  designed to provide the necessary spectroscopic diagnostics for these
  data as well as for other spectroscopic missions. The database is built
  on 3 main files for each ion: atomic energy levels, radiative data,
  and electron collisional data. The electron collision strengths are
  assessed and scaled using the Burgess and Tully scaling laws. Analyses
  of EUV line intensities often reveal discrepancies between observed
  and predicted line intensities of about of 2 when considering lines of
  the same ion. A more recent analysis has shown that it is possible to
  arrive at a subset of EUV spectral lines where the line intensities
  are reproducible to within about 25%. For X-ray lines, as will be
  observed by AXAF, there is still considerable need for energy levels,
  radiative data and collision strengths, particularly for the Δn&gt;=1
  transitions.

Title: Atomic Physics for Atmospheric Composition Measurements
Authors: Young, P. R.; Mason, H. E.
Bibcode: 1998SSRv...85..315Y
Altcode:
  The atomic physics relevant to the interpretation of solar spectra
  produced by plasmas at temperatures ≳ 105 K are discussed. Methods
  for determining relative abundance ratios are presented and examples
  provided from the Coronal Diagnostic Spectrometer on board SOHO. In
  particular, the Fe/Si ratio in the corona is found to be close to
  photospheric; the Mg/Ne ratio in the transition region is found to
  vary by an order of magnitude in different solar features. The Mg/Ne
  ratios in supergranule cell centres and the network are separated for
  the first time, although no significant differences are found.

Title: VizieR Online Data Catalog: IRON Project XXXI. Fe XII electron
    excitation (Binello+ 1998)
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
Bibcode: 1998yCat..41310153B
Altcode:
  The following tables list energy levels and electron excitation data for
  the lowest 41 levels of Fe XII (configurations 3s<SUP>2</SUP> 3p^3, 3s
  3p<SUP>4</SUP> and 3s<SUP>2 </SUP>3p<SUP>2</SUP> 3d). The table numbers
  correspond to the numbering given in the paper <P />(8 data files).

Title: Atomic data from the IRON Project. XXV. Electron impact
    excitation of fine-structure transitions in the ground configuration
    of Fe XII
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
Bibcode: 1998A&AS..127..545B
Altcode:
  In the framework of the IRON Project we have performed new, fully
  quantum mechanical atomic calculations for the Fexii (Fe(11+) )
  coronal ion. Energy levels, oscillator strengths and spontaneous decay
  transition probabilities have been computed by including extensive
  configuration interaction (CI) and relativistic effects in the
  solution of the atomic structure problem. The R-matrix approach has
  been employed to solve the electron scattering problem and generate
  a new set of collisional atomic data. Results are discussed for the
  ten fine-structure forbidden transitions in the 3s(23p^3) ground
  configuration of Fexii, and compared with previous calculations.

Title: Atomic Physics for Atmospheric Composition Measurements
Authors: Young, P. R.; Mason, H. E.
Bibcode: 1998sce..conf..315Y
Altcode:
  No abstract at ADS

Title: Surges and filaments in active regions during SOHO campaigns
Authors: Schmieder, B.; Deng, Y.; Rudawy, P.; Nitta, N.; Mandrini,
   C. H.; Fletcher, L.; Martens, P.; Innes, D.; Young, P.; Mason, H.
Bibcode: 1998ESASP.421..323S
Altcode: 1998sjcp.conf..323S
  No abstract at ADS

Title: Dynamic features observed with SOHO-CDS
Authors: Mason, H.
Bibcode: 1998ESASP.421...95M
Altcode: 1998sjcp.conf...95M
  No abstract at ADS

Title: CHIANTI - an Atomic Database For Emission Lines Paper I:
    Wavelengths Greater than 50 Angstroms
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Fossi, B. C. M.; Young,
   P. R.
Bibcode: 1998ASPC..143..390D
Altcode: 1998sigh.conf..390D
  No abstract at ADS

Title: Plasma Diagnostics for the Solar Atmosphere
Authors: Mason, Helen E.
Bibcode: 1998LNP...507..143M
Altcode: 1998sspt.conf..143M
  Superb observations are now being obtained with the ESA/NASA Solar
  Heliospheric Observatory (SOHO). In these lectures, I discuss the
  spectroscopic diagnostic techniques used to analyse ultraviolet and
  X-ray spectra. Intensities of the spectral emission lines can be used
  to determine the electron density and temperature structure, element
  abundances and dynamic nature of different features in the solar
  transition region and corona. To ensure that these techniques are
  accurate it is necessary to model all the important atomic processes
  with the best available atomic data calculations. I discuss the
  analysis of SOHO spectra and look towards other astrophysical UV and
  X-ray observations.

Title: New Results from the Coronal Diagnostic Spectrometer
Authors: Mason, H. E.; Pike, C. D.
Bibcode: 1998ASPC..154..431M
Altcode: 1998csss...10..431M
  The Coronal Diagnostic Spectrometer (CDS) on SOHO has provided
  some exciting new results on the nature of the solar transition
  region and corona. CDS has as a scientific goal the determination
  of the physical parameters of the solar plasma, using spectroscopic
  diagnostic techniques. Intensity ratios of the EUV spectral emission
  lines (150-785A) have been used to obtain information on the electron
  density and temperature structure, element abundance and the dynamic
  nature of various solar features. An overview of these CDS results is
  presented here.

Title: Solar Active Region Movies seen by the SOHO Extreme-ultraviolet
    Telescope
Authors: Newmark, J. S.; Thompson, B.; Gurman, J. B.; Delaboudiniere,
   J. P.; Aschwanden, Markus; Mason, Helen
Bibcode: 1997AAS...191.7307N
Altcode: 1997BAAS...29.1321N
  The Extreme-ultraviolet Imaging Telescope (EIT) on board the SOHO (SOlar
  and Heliospheric Observatory) satellite provides wide-field images of
  the corona and transition region on the solar disc and up to 1.4 solar
  radii above the limb. Its normal incidence multilayer-coated optics
  select spectral emission lines from FeIX (171 Ang), FeXII (195 Ang),
  FeXV (284 Ang), and HeII (304 Ang) with 2.6 arcsecond resolution which
  allow us to describe Solar activity over a wide temperature range. EIT
  is providing unique EUV observations of the structure and evolution of
  active regions. Here we show movies of active region 8059 from July
  3-10, 1997. The high temporal variability of the AR loops is very
  evident. Initial temperature and density diagnostics are explored as
  well as a comparison with diagnostics from the SOHO-CDS instrument.

Title: Active Regions Observed in Extreme Ultraviolet Light by the
    Coronal Diagnostic Spectrometer on SOHO
Authors: Fludra, A.; Brekke, P.; Harrison, R. A.; Mason, H. E.; Pike,
   C. D.; Thompson, W. T.; Young, P. R.
Bibcode: 1997SoPh..175..487F
Altcode:
  We present observations of five active regions made by the Coronal
  Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory
  (SOHO). CDS observes the Sun in the extreme ultraviolet range 150-780
  Å. Examples of active region loops seen in spectral lines emitted at
  various temperatures are shown. Several classes of loops are identified:
  those that are seen in all temperatures up to 2 x 10<SUP>6</SUP> K;
  loops seen at 10<SUP>6</SUP> K but not reaching 1.6 x 10<SUP>6</SUP>
  K; those at temperatures 2- 4 x 10<SUP>-5</SUP> K and occasionally at
  6 x 10<SUP>-5</SUP> K but not reaching 10<SUP>6</SUP> K. An increasing
  loop size with temperature and the relationship between the cool and
  hot structures is discussed. CDS observations reveal the existence of
  loops and other unresolved structures in active regions, at temperatures
  between 1.5- 4 x 10<SUP>-5</SUP> K, which do not have counterparts in
  lines emitted above 8 x 10<SUP>-5</SUP> K. Bright compact sources only
  seen in the transition region lines are investigated. These sources can
  have lifetimes of up to several days and are located in the vicinity
  of sunspots. We study the variability of active region sources on time
  scales from 30 sec to several days. We find oscillatory behaviour of Hei
  and Ov line intensities in an active region on time scales of 5-10 min.

Title: CHIANTI - an atomic database for emission lines
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Monsignori Fossi,
   B. C.; Young, P. R.
Bibcode: 1997A&AS..125..149D
Altcode:
  A comprehensive set of accurate atomic data is required for analyses of
  astrophysical and solar spectra. CHIANTI provides a database of atomic
  energy levels, wavelengths, radiative data and electron excitation
  data for ions which are abundant in cosmic plasmas. The most recent
  electron excitation data have been assessed and stored following
  the method of \cite[Burgess \&amp; Tully (1992)]{bur92}. The current
  version is essentially complete for specifying the emission spectrum
  at wavelengths greater than 50 Angstroms. A list of observed lines in
  the spectral region between 50 and 1100 Angstroms has been compiled
  and compared with the lines predicted by the CHIANTI database. The
  CHIANTI database reproduces the vast majority of lines observed at
  these wavelengths. CHIANTI includes IDL (Interactive Data Language)
  routines to calculate optically thin synthetic spectra for equilibrium
  conditions. IDL routines to calculate theoretical line intensities
  required for electron density or temperature diagnostics and emission
  measure studies are also included. The CHIANTI atomic database and
  supporting IDL routines are available by anonymous FTP.

Title: Soho Cds nis in-flight intensity calibration using a plasma
    diagnostic method
Authors: Landi, E.; Landini, M.; Pike, C. D.; Mason, H. E.
Bibcode: 1997SoPh..175..553L
Altcode:
  The internal intensity calibration of the Coronal Diagnostic
  Spectrometer (CDS) - Normal Incidence Spectrometer (NIS) is studied
  using the Arcetri diagnostic method. A large number of spectral lines
  observed by the CDS-NIS 1 and NIS 2 windows in a solar active region
  is analysed in order to determine the intensity calibration curve for
  both channels.

Title: The Mg/Ne abundance ratio in a recently emerged flux region
    observed by CDS
Authors: Young, P. R.; Mason, H. E.
Bibcode: 1997SoPh..175..523Y
Altcode:
  Evidence for the existence of the FIP-effect in the transition region is
  presented here based on recent observations from the Coronal Diagnostic
  Spectrometer (CDS) on-board the Solar and Heliospheric Observatory
  (SOHO). Observations of an emerging flux region in lines of Mgv-vii and
  Nevi-vii reveal differences in the relative Mg/Ne abundance of a factor
  of 9.2 between two transition region brightenings separated by less
  than 1 arc min on the Sun. The lower abundance ratio is approximately
  equal to the photospheric Mg/Ne value and is associated with a small
  loop-like feature in the central, hottest part of the active region. The
  higher abundance ratio is found in spike-like structures at the edge
  of the active region. A density diagnostic of Oiv is used to derive
  an electron number density of 10<SUP>11.3</SUP> cm<SUP>-3</SUP> for
  the low Mg/Ne brightening, while a Mgvii diagnostic gives a density
  of 10<SUP>9.2</SUP> cm for the high Mg/Ne brightening.

Title: The Ar/Ca relative abundance in solar coronal plasma.
Authors: Young, P. R.; Mason, H. E.; Keenan, F. P.; Widing, K. G.
Bibcode: 1997A&A...323..243Y
Altcode:
  The relative abundances of elements with low and high first
  ionisation potentials (FIP) is a subject of much recent debate. In
  situ measurements of the solar wind reveal a clear pattern of low
  FIP enhancement that has been followed up with various spectroscopic
  measurements of the solar corona. Argon is unique amongst the more
  abundant high FIP elements in retaining several of its electrons at
  the high temperatures seen in flares. This allows emission lines of
  different ions to be compared with more confidence than for, say,
  hydrogen-like high FIP ions such as OVIII and NeX. In this paper we
  look at emission lines of the boron-like ion ArXIV; in particular,
  the optical line at 4412Å, seen in eclipse observations, is compared
  to the CaXIII 4086Å and CaXV 5445Å &amp; 5694Å lines to yield an
  Ar/Ca abundance of 0.85+/- 0.20. In the extreme ultra-violet (EUV),
  the ArXIV lines at 187.94Å and 194.41Å can be compared with CaXIV
  193.87 Å - flare data from Skylab giving values of 1.10+/-0.25 and
  0.55+/-0.21. Analysis of previous work indicates a photospheric Ar/Ca
  abundance of 1.31+/-0.30, hence supporting the conclusion that elements
  with high FIP have lower coronal abundances.

Title: VizieR Online Data Catalog: CHIANTI - An Atomic Database For
    Emission Lines I. (Dere+ 1997)
Authors: Dere, K. P.; Landi, E.; Mason, H. E.; Monsignori Fossi,
   B. C.; Young, P. R.
Bibcode: 1997yCat..41250149D
Altcode:
  A comprehensive set of accurate atomic data is required for analyses of
  astrophysical and solar spectra. CHIANTI provides a database of atomic
  energy levels, wavelengths, radiative data and electron excitation
  data for ions which are abundant in cosmic plasmas. The most recent
  electron excitation data have been assessed and stored following
  the method of Burgess &amp; Tully (1992A&amp;A...254..436B). The
  current version is essentially complete for specifying the emission
  spectrum at wavelengths greater than 50Å. A list of observed lines
  in the spectral region between 50 and 1100Å has been compiled
  and compared with the lines predicted by the CHIANTI database. The
  CHIANTI database reproduces the vast majority of lines observed at
  these wavelengths. CHIANTI includes IDL (Interactive Data Language)
  routines to calculate optically thin synthetic spectra for equilibrium
  conditions. IDL routines to calculate theoretical line intensities
  required for electron density or temperature diagnostics and emission
  measure studies are also included. The CHIANTI atomic database and
  supporting IDL routines are available by anonymous FTP. (1 data file).

Title: UV and soft X-ray lines from Fe XVI observed in solar and
    stellar spectra.
Authors: Cornille, M.; Dubau, J.; Mason, H. E.; Blancard, C.; Brown,
   W. A.
Bibcode: 1997A&A...320..333C
Altcode:
  The ion Fe XVI is abundant in solar active regions and flares. Strong
  spectral lines from this ion have been observed over a wide wavelength
  range. The transitions 3s-3p and 3p-3d fall between 250 and 365Å and
  lines from transitions between n=3 to n=4, n=3 to n=5 fall between
  30 and 80Å. In this paper, we present distorted wave results for
  the electron scattering collision strengths from the ground level to
  all the other levels and discuss previous calculations. We compare
  our theoretical intensity ratios with solar observations and show
  that the strongest spectral lines in the X-ray wavelength range do
  not correspond to the dipole transitions, 3s-4p, 3s-5p, as might be
  expected. We comment on the approximations which have been generally
  used in synthetic spectrum programs to simulate the Fe XVI spectral
  line intensities and the consequences for analyses of solar and
  stellar spectra.

Title: Spectral Line Intensities for n = 3-3 EUV Transitions in Fe XV
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1997ADNDT..66..119B
Altcode:
  Transition rates and collision strengths between the
  fine-structure levels of Fe XV have been calculated using
  the configurations 3s<SUP>2</SUP>, 3s3p, 3p<SUP>2</SUP>,
  3s3d, 3p3d, and 3d<SUP>2</SUP>and are compared here with other
  calculations. The present calculations were carried out using the
  Superstructure and distorted-wave programs developed at University
  College, London. Level populations and line intensity ratios
  are calculated for three temperatures with logT<SUB>e</SUB>(K)
  = 6.2, 6.4, and 6.6 and for electron densitiesN<SUB>e</SUB>=
  10<SUP>8</SUP>-10<SUP>12</SUP>cm<SUP>-3</SUP>. Calculated intensity
  ratios of the emission lines are compared with those observed by
  the Solar EUV Rocket Telescope and Spectrograph (SERTS) in an active
  region of sun. The present results should also be useful in analyzing
  observations from the Solar Heliospheric Observatory (SOHO).

Title: New atomic data for the FeXII coronal ion
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.
Bibcode: 1997AdSpR..20.2263B
Altcode:
  Various FeXII spectroscopic lines in the UV and EUV range have been
  proved to be ideal diagnostic tools for measuring electron temperature,
  density and iron abundance in the solar corona. In the framework of the
  ``IRON PROJECT'' we have provided improved theoretical calculations
  of the atomic data required to analyse the intensity of these lines
  and to apply the results to SOHO (Solar Heliospheric Observatory)
  observations. Extensive configuration interaction and relativistic
  effects have been allowed for in the atomic structure computations which
  have provided energy levels and an extensive set of radiative data. The
  e-FeXII collisional problem has been tackled with the multichannel
  R-matrix method, a close-coupling calculation for the determination
  of electron impact collision strengths. Final results are presented
  for FeXII thermally averaged collision strengths, for fine-structure
  forbidden transitions within the ground configuration.

Title: Application of Spectroscopic Diagnostics to Early Observations
    with the SOHO Coronal Diagnostic Spectrometer
Authors: Mason, H. E.; Young, P. R.; Pike, C. D.; Harrison, R. A.;
   Fludra, A.; Bromage, B. J. I.; Del Zanna, G.
Bibcode: 1997SoPh..170..143M
Altcode:
  The Coronal Diagnostic Spectrometer (CDS) has as a scientific goal
  the determination of the physical parameters of the solar plasma
  using spectroscopic diagnostic techniques. Absolute intensities and
  intensity ratios of the EUV spectral emission lines can be used to
  obtain information on the electron density and temperature structure,
  element abundances, and dynamic nature of different features in the
  solar atmosphere. To ensure that these techniques are accurate it is
  necessary to interface solar analysis programs with the best available
  atomic data calculations. Progress is reported on this work in relation
  to CDS observations.

Title: Extreme ultraviolet observations of the solar corona: first
    results from the coronal diagnostic spectrometer on SOHO
Authors: Harrison, R. A.; Fludra, A.; Sawyer, E. C.; Culhane, J. L.;
   Norman, K.; Poland, A. I.; Thompson, W. T.; Kjeldseth-Moe, O.;
   Aschenbach, B.; Huber, M. C. E.; Gabriel, A. H.; Mason, H. E.
Bibcode: 1997AdSpR..20.2239H
Altcode:
  We present first results from the Coronal Diagnostic Spectrometer (CDS)
  aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO). CDS is
  a double spectrometer operating in the 151-785 A˚ range. This region
  of the solar spectrum is rich in emission lines from trace elements
  in the solar atmosphere, which can be used to derive diagnostic
  information on coronal and transition region plasma. Early spectra are
  presented and well identified lines are listed. In addition, examples
  of images in selected wavelength ranges are shown, for a prominence,
  a loop system and a bright point, demonstrating well the power of such
  extreme ultraviolet observations.

Title: High Coronal Electron Densities in a Solar Flare from Fe XXI
    and Fe XXII X-Ray Line Measurements
Authors: Phillips, K. J. H.; Bhatia, A. K.; Mason, H. E.; Zarro, D. M.
Bibcode: 1996ApJ...466..549P
Altcode:
  New calculations of the intensities of the Fe XXI 2p<SUP>2</SUP>-2p4l
  X-ray lines using the distorted wave method are described and compared
  with observations made by a crystal spectrometer on the Solar Maximum
  Mission about 6 minutes after the peak of a very intense flare. The
  comparison enables the electron density of the flare to be derived,
  the value being about 2 or 3 × 10<SUP>12</SUP> cm<SUP>-3</SUP>. Some
  nearby Fe XXII X-ray lines, scanned 1 minute after flare peak, give an
  even higher value, 10<SUP>13</SUP> cm<SUP>-3</SUP>. This is the first
  time corroborated values of such high densities have been obtained
  from ions emitted at temperatures as high as ∼10 MK. They imply very
  rapid radiation cooling rates and have other important consequences
  for flare models.

Title: CHIANTI - an Atomic Database for Emission Line Spectroscopy:
    Version 1 - Wavelengths greater than 50 Angstroms
Authors: Dere, K. P.; Monsignori-Fossi, B. C.; Landi, E.; Mason,
   H. E.; Young, P. R.
Bibcode: 1996AAS...188.8501D
Altcode: 1996BAAS...28..961D
  A comprehensive set of accurate atomic data is required for analyses of
  astrophysical and solar spectra. CHIANTI provides an atomic database of
  energy levels (wavelengths), radiative data and electron excitation data
  for ions which are abundant in astrophysical plasmas. The most recent
  electron excitation data have been assessed and stored following the
  method of Burgess and Tully (1992). CHIANTI includes IDL (Interactive
  Data Language) routines to produce optically thin synthetic spectra
  for lambda &gt; 50 Angstroms, assuming equilibrium conditions. It also
  includes IDL routines to calculate theoretical line intensities required
  for electron density or temperature diagnostics and emission measure
  studies. The CHIANTI atomic database and supporting IDL routines are
  available by anonymous FTP.

Title: Atomic data from the IRON Project. XIV. Electron
    impact excitation of the Fe XIV fine-structure transition
    ^2^P^o^_1/2_-^2^P^o^_3/2_
Authors: Storey, P. J.; Mason, H. E.; Saraph, H. E.
Bibcode: 1996A&A...309..677S
Altcode:
  We calculate collision strengths and collision rates for electron
  excitation of the ^2^P^o^_1/2_-^2^P^o^_3/2_ ground term fine-structure
  transition in Fe xiv, the coronal green line at 5303A. The collision
  strength for the green line is found to be strongly enhanced by
  resonances for the first 4 Rydberg above the excitation threshold, and
  as a result the collision rates are found to be significantly larger
  than other recently published results, even at coronal temperatures. The
  calculations are carried out using the R-matrix formulation of the
  close-coupling approximation.

Title: New atomic data for the FeXII coronal ion
Authors: Binello, A. M.; Mason, H. E.; Storey, P. J.; Kohl, J.
Bibcode: 1996ASPC..109..251B
Altcode: 1996csss....9..251B
  No abstract at ADS

Title: EUV density diagnostics in solar and stellar spectra
Authors: Young, P. R.; Mason, H. E.
Bibcode: 1996ASPC..109..301Y
Altcode: 1996csss....9..301Y
  No abstract at ADS

Title: EUV Line Intensities of Fe X
Authors: Young, P. R.; Mason, H. E.; Bhatia, A. K.; Doschek, G. A.;
   Thomas, R. J.
Bibcode: 1996aeu..conf..583Y
Altcode: 1996IAUCo.152..583Y
  No abstract at ADS

Title: Plasma Emission Codes: Comparisons and Critiques
Authors: Mason, Helen E.
Bibcode: 1996aeu..conf..561M
Altcode: 1996IAUCo.152..561M
  No abstract at ADS

Title: High coronal electron densities in a solar flare from Fe XXI
    and Fe XXII X-ray line ratios.
Authors: Phillips, K. J. H.; Bhatia, A. K.; Mason, H. E.; Zarro, D. M.
Bibcode: 1996uxsa.conf...75P
Altcode: 1996uxsa.coll...75P
  New distorted-wave calculations of the intensities of the Fe XXI
  2p<SUP>2</SUP> - 2p4l X-ray lines are described and compared with
  observations made during an unusually intense flare. The density
  sensitivity of some of the lines implies that N<SUB>e</SUB> is between
  10<SUP>12</SUP> and 10<SUP>13</SUP>cm<SUP>-3</SUP>. An even higher value
  (10<SUP>13</SUP>cm<SUP>-3</SUP>) is obtained from nearby Fe XXII 2p -
  4d lines. This is the first time such high densities have been measured
  from ions emitted at temperatures as high as ≡10<SUP>7</SUP>K. They
  imply very rapid radiation cooling rates, and have other important
  consequences for flare models.

Title: Atomic data for solar VUV spectroscopy (SOHO).
Authors: Mason, H. E.
Bibcode: 1996uxsa.conf..213M
Altcode: 1996uxsa.coll..213M
  A great deal of effort in recent years has gone into the development of
  spectroscopic techniques to probe the physical parameters of the solar
  atmosphere. One aspect of this work is the calculation of new atomic
  data and the development of plasma emission codes to study spectral
  lines. This work is being carried out in preparation for the SOHO
  (Solar Heliospheric Observatory). In this paper, the author presents
  an overview of the atomic processes involved and an assessment of
  the accuracy of the parameters which are required for spectroscopic
  diagnostics in the EUV and UV wavelength ranges.

Title: The Coronal Diagnostic Spectrometer for the Solar and
    Heliospheric Observatory
Authors: Harrison, R. A.; Sawyer, E. C.; Carter, M. K.; Cruise,
   A. M.; Cutler, R. M.; Fludra, A.; Hayes, R. W.; Kent, B. J.; Lang,
   J.; Parker, D. J.; Payne, J.; Pike, C. D.; Peskett, S. C.; Richards,
   A. G.; Gulhane, J. L.; Norman, K.; Breeveld, A. A.; Breeveld, E. R.; Al
   Janabi, K. F.; Mccalden, A. J.; Parkinson, J. H.; Self, D. G.; Thomas,
   P. D.; Poland, A. I.; Thomas, R. J.; Thompson, W. T.; Kjeldseth-Moe,
   O.; Brekke, P.; Karud, J.; Maltby, P.; Aschenbach, B.; Bräuninger,
   H.; Kühne, M.; Hollandt, J.; Siegmund, O. H. W.; Huber, M. C. E.;
   Gabriel, A. H.; Mason, H. E.; Bromage, B. J. I.
Bibcode: 1995SoPh..162..233H
Altcode:
  The Coronal Diagnostic Spectrometer is designed to probe the solar
  atmosphere through the detection of spectral emission lines in the
  extreme ultraviolet wavelength range 150 - 800 å. By observing
  the intensities of selected lines and line profiles, we may derive
  temperature, density, flow and abundance information for the plasmas
  in the solar atmosphere. Spatial and temporal resolutions of down to
  a few arcseconds and seconds, respectively, allow such studies to be
  made within the fine-scale structure of the solar corona. Futhermore,
  coverage of large wavelength bands provides the capability for
  simultaneously observing the properties of plasmas across the wide
  temperature ranges of the solar atmosphere.

Title: The application of atomic physics to the study of solar
    abundances and their variations
Authors: Mason, H. E.
Bibcode: 1995AdSpR..15g..53M
Altcode: 1995AdSpR..15R..53M
  The determination of elemental abundances in the solar atmosphere
  depends critically on the accuracy of the atomic physics assumed
  in the models. Uncertainties in the electron-ion excitation rates,
  ionisation and recombination rates or other atomic processes can lead
  to variations in the derived relative abundance values. In this paper,
  the different methods used in the analyses of UV and X-ray spectra are
  explored. Particular attention is paid to the accuracy of the atomic
  parameters and the assumptions made in the atomic model. A summary is
  given of the most recent theoretical and laboratory work. Implications
  for analyses of existing solar datasets and proposed observations
  (SOHO) are discussed.

Title: Atomic data and coronal diagnostics
Authors: Mason, H. E.
Bibcode: 1995HiA....10..303M
Altcode:
  No abstract at ADS

Title: EUV and infra-red lines of FE XIII
Authors: Young, P. R.; Mason, H. E.; Thomas, R. J.
Bibcode: 1994ESASP.373..417Y
Altcode: 1994soho....3..417Y
  No abstract at ADS

Title: Spectroscopic diagnostics in the VUV for solar and stellar
    plasmas
Authors: Mason, H. E.; Fossi, B. C. Monsignori
Bibcode: 1994A&ARv...6..123M
Altcode:
  The VUV emission spectra from the solar atmosphere and stellar
  atmospheres have been intensively studied during the past 25 years
  with several major space programs. In this review we discuss the
  spectroscopic diagnostic techniques used to study astrophysical plasmas,
  the atomic processes involved, the recent observations and the plans
  for future space missions.

Title: Spectroscopic diagnostics for CDS and SUMER
Authors: Mason, Helen E.
Bibcode: 1994SSRv...70..111M
Altcode:
  The CDS and SUMER instruments will make extensive use of spectroscopic
  diagnostics to determine the physical parameters of the solar transition
  region and corona. A great deal of effort is going into the development
  of these techniques to ensure that they are accurate. This requires
  interfacing solar analysis programs with the best available atomic
  data calculations. Recent developments in this work will be presented,
  with specific examples of useful spectral line ratios.

Title: An Assessment of Theoretical Electron Excitation Data for Fe
    IX-Fe XIV
Authors: Mason, H. E.
Bibcode: 1994ADNDT..57..305M
Altcode:
  The available theoretical electron excitation data for Fe IX-Fe
  XIV are assessed and recommendations are made for improvement in
  future work. The averaged collision strengths are obtained using
  the interactive, graphical programs of Burgess and Tully. Accurate
  calculations for these ions are very difficult to carry out because
  of the complexity of the n = 3 target wave functions. It is evident
  that a substantial amount of work is still required for some of the
  ions to obtain results with a high accuracy.

Title: A New Synthetic XUV Spectrum
Authors: Dere, K. P.; Mason, H. E.; Fossi, B. C. Monsignori; Waljeski,
   K. H.
Bibcode: 1993AAS...18311203D
Altcode: 1993BAAS...25.1459D
  We have begun a program to develop a synthetic XUV spectrum for the
  70 - 2500 /AA wavelength region based on a critical analysis of the
  most recent calculations of atomic parameters, in particular, atomic
  collision strengths and their thermal averages. Ultraviolet spectra
  returned by the EUVE and HST instruments demonstrate a continued need
  for the most accurate atomic parameters in order to determine the
  physical conditions in the emitting plasmas. Most previous synthetic
  spectra has relied heavily on the gaunt factor approximation which can
  predict excitation rates only for dipole transitions and only to within
  a factor of 2 to 3. In many cases, direct calculations of the collision
  strengths are now available. Burgess and Tully (1992) have developed
  a technique for critically evaluating collision strength calculations
  and scaling and compacting the data. Different scalings are available
  for resonance, intercombination and forbidden excitations. This method
  will be applied in the construction of our spectrum. In the end, we
  intend to produce a set of critically evaluated atomic parameters
  from which the nearly optically thin spectrum of a low density
  astrophysical plasma can be calculated, together with the programs
  necessary to perform these calculations. We will include the ability
  to prescribe elemental abundances and to correct for optical depth
  and populations of metastable levels as a function of density. The
  data sets and programs will be made available by anonymous ftp.

Title: Nonthermal Velocities in the Solar Transition Zone Observed
    with the High-Resolution Telescope and Spectrograph
Authors: Dere, K. P.; Mason, H. E.
Bibcode: 1993SoPh..144..217D
Altcode:
  Data obtained during the first rocket flight of the NRL High Resolution
  Telescope and Spectrograph (HRTS) have been used to study nonthermal
  velocities for spectral lines primarily covering the temperature
  range 10<SUP>4</SUP> to 2 × 10<SUP>6</SUP> K. The high spectral and
  spatial resolution, combined with an enhanced dynamic intensity range
  of the reduced data, has enabled us to study the distribution of the
  nonthermal velocities for quiet and active regions. Average values
  of the nonthermal velocities peak at about 27 km s<SUP>−1</SUP>
  at 10<SUP>5</SUP> K for the quiet regions, with a wide distribution
  of nonthermal velocities for each line. The active region nonthermal
  velocities have a narrower distribution which is weighted towards higher
  values. The SiIV and C IV line profiles are not well described by a
  single Gaussian, indicating that high-velocity components (above 30 km
  s<SUP>−1</SUP>) are present in the quiet-Sun spectra. The radiative
  losses for all plasma above l0<SUP>5</SUP> K have been calculated for
  the quiet Sun, an active region and a coronal hole. These have been
  compared with the acoustic wave flux inferred from the nonthermal line
  widths. There appears to be a sufficient flux of waves to heat these
  regions of the atmosphere.

Title: Atomic data for the SOHO mission.
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
Bibcode: 1993uxrs.conf...97B
Altcode: 1993uxsa.conf...97B
  An interactive computer program has been developed by Burgess and Tully
  (1992) to assess and store electron excitation collision rates. The
  program is being used to prepare atomic data which is required to
  analyse solar and astrophysical spectra. In this paper, the authors
  present work in progress on several solar ions with spectral lines in
  the UV wavelength region. These will be observed by the CDS and SUMER
  instruments to be flown on the SOHO mission.

Title: UV and soft X-ray lines from Fe XVI observed in solar and
    stellar spectra.
Authors: Cornille, M.; Dubau, J. A.; Mason, H. E.; Blancard, C.;
   Brown, W. A.
Bibcode: 1993uxrs.conf..101C
Altcode: 1993uxsa.conf..101C
  The ion Fe XVI is abundant in solar active regions and flares. Strong
  spectral lines from this ion have been observed over a wide wavelength
  range (30-365 Å) both in astrophysical and laboratory plasmas. In this
  paper, the authors present new electron scattering collision rates and
  compare their theoretical intensity ratios with solar observations. The
  authors note that the approximations often used to simulate Fe XVI
  soft X-ray lines in solar and stellar spectra are inaccurate.

Title: Abundance determination in the quiet corona.
Authors: Mason, Helen E.
Bibcode: 1992ESASP.348..297M
Altcode: 1992cscl.work..297M
  A study is made of the determination of element abundances in the quiet
  regions of the solar transition zone and corona. The early work with EUV
  spectral lines, which is cited in the paper by Meyer (1985), is reviewed
  together with subsequent analyses of Skylab observations. The intention
  of this paper is to question some of the assumptions which have been
  made in these analyses and to look critically at the accuracy of past
  and present atomic data. The overall aim is to assess what further work
  is required to adapt these methods for use as diagnostic techniques
  with the SOHO instruments, in particular CDS and SUMER. Mention is
  also made of the importance of studying the coronal forbidden lines
  in the visible and infra-red wavelength regions.

Title: Atomic Physics Calculations Relevant to Solar Flare Spectra
Authors: Mason, Helen E.
Bibcode: 1991RSPTA.336..471M
Altcode:
  Solar flare spectra in the ultraviolet and X-ray wavelength regions
  are rich in emission lines from highly ionized ions, formed at
  temperatures around 10<SUP>7</SUP> K. These lines can be used as
  valuable diagnostics for probing the physical conditions in solar
  flares. Such analyses require accurate atomic data for excitation,
  ionization and recombination processes. In this paper, we present
  a review of work which has already been carried out, in particular
  for the Solar Maximum Mission observations, and we look to future
  requirements for Solar-A.

Title: A Critical Assessment of Electron Excitation between the 2s
    22p 2 and 2s2p 3 Configurations of MG +6
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
Bibcode: 1991ApJ...376..803B
Altcode:
  Using the programs RMATRX and DSTWAV, which are based, respectively,
  on the close coupling and distorted wave approximations, we
  compute and compare partial collision strengths for the optically
  allowed transitions between the 2s<SUP>2</SUP>2p<SUP>2</SUP>
  and 2s2p<SUP>3</SUP> configurations of Mg<SUP>+6</SUP>. From this
  investigation we conclude that the differences between the published
  results of Mason and Bhatia (DSTWAV) and Aggarwal (RMATRX) arise not
  simply because they used different target wave functions, but also
  because the method used by Aggarwal for treating the outer region in
  his close coupling calculation is inadequate for optically allowed
  transitions.

Title: Nonthermal Velocities in the Solar Transition Region
Authors: Dere, K. P.; Mason, H. E.
Bibcode: 1991BAAS...23Q1028D
Altcode:
  No abstract at ADS

Title: IR Line Radiation : A Program for Interpolating Atomic
    Collision Data
Authors: Burgess, A.; Chidichimo, M. C.; Mason, H. E.; Tully, J. A.
Bibcode: 1991isrs.conf..105B
Altcode:
  No abstract at ADS

Title: Atomic physics calculations relevant to solar flare spectra.
Authors: Mason, H. E.
Bibcode: 1991psf..conf..471M
Altcode:
  Solar flare spectra in the ultraviolet and X-ray wavelength
  regions are rich in emission lines from highly ionized ions, formed
  at temperatures around 10<SUP>7</SUP>K. These lines can be used as
  valuable diagnostics for probing the physical conditions in solar
  flares. Such analyses require accurate atomic data for excitation,
  ionization and recombination processes. The author presents a review
  of work which has already been carried out, in particular for the
  Solar Maximum Mission observations.

Title: Collision Strengths and Oscillator Strengths for Fe IX
Authors: Fawcett, B. C.; Mason, H. E.
Bibcode: 1991ADNDT..47...17F
Altcode:
  Collision strengths and oscillator strengths are calculated for
  Fe IX. The three configurations 3 s<SUP>2</SUP>3 p<SUP>6</SUP>, 3
  s<SUP>2</SUP>3 p<SUP>5</SUP>3 d, and 3 s<SUP>2</SUP>3 p<SUP>5</SUP>4
  s were included in the computations. The data can be applied to
  the analysis of spectral lines in the solar spectrum and laboratory
  sources. The collision calculations were executed with the DISTORTED
  WAVE collision code and SUPERSTRUCTURE atomic-structure code
  interfaced via transformation code JAJOM. These codes were written
  at University College London. As reported in a previous publication,
  the codes were adapted to enable the adjustment of Slater parameters
  leading to improved energy levels and eigenvectors. The Cowan suite
  of atomic-structure codes was used to generate the adopted optimized
  parameters and also to compute oscillator strenghts. Possible
  application of the method to more complex atomic structures was
  investigated.

Title: Density measurements in the corona
Authors: Mason, Helen E.
Bibcode: 1991AdSpR..11a.293M
Altcode: 1991AdSpR..11..293M
  A knowledge of the electron density in the solar atmosphere is
  fundamental to our understanding of the dominant physical processes. The
  field of spectroscopic diagnostics is therefore an area of major
  interest in the analysis of space observations. In this paper, we
  review techniques which are used for determining the electron density
  in the corona, with reference to UV and X-ray observations. Particular
  attention is given to the accuracy of the methods, including an
  assessment of the atomic parameters. Future projects are discussed,
  such as the CDS and SUMER instruments on SOHO which will make extensive
  use of spectroscopic diagnostics.

Title: The Interpretation of the Spectral Line Intensities from the
    Chase Spectrometer on SPACELAB-2
Authors: Lang, J.; Mason, H. E.; McWhirter, R. W. P.
Bibcode: 1990SoPh..129...31L
Altcode:
  In this paper we analyse the solar spectral intensities observed
  with the CHASE grazing incidence telescope and spectrometer flown
  on NASA's Spacelab 2 Mission in 1985. Our main purpose has been to
  investigate the sources of error that arise in the application of the
  differential emission measure technique used to analyse such data. We
  suggest methods by which these sources of error may be investigated.

Title: Spectroscopic diagnostics for ions observed in solar and
    cosmic plasmas
Authors: Mason, Helen E.
Bibcode: 1990hrxr.conf...11M
Altcode: 1990IAUCo.115...11M
  The X-ray wavelength region (1-200 A) is rich in spectral lines
  from highly ionized systems. Spectra from the solar atmosphere have
  been studied extensively with various instruments covering different
  wavelength regions. The solar spectral line emission with particular
  reference to iron ions and helium-like ions observed during solar
  flares is discussed. The atomic processes involved in the calculation of
  theoretical intensities for low-density plasmas are outlined together
  with the diagnostic properties of the emission lines. Comparisons are
  made with available cosmic X-ray spectra and predicted spectra for
  future projects, such as AXAF.

Title: UV and EUV Spectroscopy of the Upper Solar Atmosphere
Authors: Mason, H. E.
Bibcode: 1990PDHO....7..232M
Altcode: 1990dysu.conf..232M; 1990ESPM....6..232M
  The UV and EUV wavelength regions are rich in emission lines from the
  transition region and the corona. Spectroscopic diagnostic techniques
  have been used extensively to determine the physical conditions in the
  solar atmosphere for such diverse phenomena as coronal holes, active
  regions surges, flares. The author reviews diagnostic techniques which
  have been used in the analyses of space observations (eg Skylab, SMM,
  HRTS, CHASE) and looks to future projects such as the CDS and SUMER
  instruments on SOHO which cover the UV and EUV wavelength regions
  and will provide a wealth of observations with excellent spatial,
  spectral and temporal resolution.

Title: A comparison of theoretical and solar-flare intensity ratios
    for the Fe XIX X-ray lines
Authors: Bhatia, A. K.; Fawcett, B. C.; Phillips, K. J. H.; Lemen,
   J. R.; Mason, H. E.
Bibcode: 1989MNRAS.240..421B
Altcode:
  Atomic data including energy levels, gf-values, and wavelengths are
  given for the Fe XIX transitions that give rise to lines in solar-flare
  and active-region X-ray spectra. Collision strengths and theoretical
  intensity ratios are presented for lines which occur in the 13.2-14.3-A
  range. Observed spectra are found to be consistent with those derived
  from the present Fe XIX atomic data. For the case of spectra in which
  the Fe XIX lines are very strong, such as those at the maxima of hot
  flares, two observed line features due to Fe XIX are shown to have
  larger intensities than calculated. The calculated Fe XIX and Ne IX line
  spectra are used to determine electron densities from Ne IX line ratios.

Title: Solar Astrophysics SIG
Authors: Mason, Helen
Bibcode: 1989StarB...4....9M
Altcode:
  No abstract at ADS

Title: Coronal Mg(9+) - Collisional excitation of the 2s-2p multiplet
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
Bibcode: 1989A&A...217..319B
Altcode:
  Electron impact excitation of the astrophysically important 2s-2p
  multiplet in lithium-like Mg(9+) is discussed. The collision strength
  for this optically allowed transition is computed using a two state
  model ion with the close coupling approximation. At high impact energies
  a distorted wave approximation is used. The contribution from distant
  encounters is determined by the Coulomb Bethe approximation. The
  Burgess-Tully method is used to interpolate the results and to
  evaluate the thermally averaged collision strength from which the rate
  coefficient is readily obtained.

Title: A Slater Parameter Optimization Method Applied to the
    Computation of Collision Strengths for Fe XIII
Authors: Fawcett, B. C.; Mason, H. E.
Bibcode: 1989ADNDT..43..245F
Altcode:
  Details of a new computational method for calculating collision
  strengths are presented through an application to Fe XIII. The method,
  which enables the computation of collision strengths for complex ions,
  is adapted from long-established optimization techniques previously
  used for the calculation of atomic energy levels and oscillator
  strengths. The procedure involves the adjustment of Slater parameters
  and average energies of configurations so that they result in improved
  energy levels and eigenvectors. These improved values can then provide
  a basis for collision strength calculations in ions where ab initio
  computations break down or result in unnecessarily large errors. The
  present application is implemented through modifications of the
  DISTORTED WAVE collision code and SUPERSTRUCTURE atomic-structure
  code interfaced via a transformation code JAJOM, which also processes
  their output; these atomic codes were written at University College
  London. It should be feasible to make similar adaptions to other
  collision codes. The Cowan suite of atomic-structure codes generated
  the optimized parameters. Fe XIII collision strengths are tabulated for
  3 s<SUP>2</SUP>3 p<SUP>2</SUP>-3 s3 p<SUP>3</SUP> and 3 s<SUP>2</SUP>3
  p<SUP>2</SUP>-3 s<SUP>2</SUP>3 p3 d transitions. Six configurations,
  3 s<SUP>2</SUP>3 p<SUP>2</SUP>, 3 p<SUP>4</SUP>, 3 s3 p<SUP>3</SUP>,
  3 s<SUP>2</SUP>3 p3 d, 3 s3 p3 d<SUP>2</SUP>, and 3 p<SUP>3</SUP>3 d,
  were included in these computations.

Title: Solar Astrophysics
Authors: Mason, Helen
Bibcode: 1988StarB...2....8M
Altcode:
  No abstract at ADS

Title: A New Aid for Interpolating and Assessing Collision Strengths
    and Rate Coefficients
Authors: Burgess, A.; Mason, H. E.; Tully, J. A.
Bibcode: 1988JPhys..49..107B
Altcode: 1988IAUCo.102..107B
  No abstract at ADS

Title: Spectroscopic techniques for determining electron densities
    in the solar atmosphere.
Authors: Mason, H. E.
Bibcode: 1988JPhys..49...13M
Altcode: 1988IAUCo.102...13M
  An overview is given of the methods used for determining electron
  densities in the solar atmosphere. This includes a discussion of the
  accuracy of the atomic parameters required in such analyses. Several
  different approximations are used to calculate electron scattering
  cross-sections. These are outlined and their accuracy for individual
  ions is assessed. A lot of effort has gone into the determination
  of the electron densities in solar flares, particularly during the
  impulsive phase. Such studies are crucial to distinguish between various
  theoretical flare models. These problems are discussed in relation to
  analyses of spectral data from SKYLAB, HRTS, SMM, SOLEX and XSST and
  with a view to future projects such as SOHO.

Title: Spectral Line Profiles of Fe XXI 1354.1 Angstrom from the
    Solar Maximum Mission
Authors: Mason, H. E.; Shine, R. A.; Gurman, J. B.; Harrison, R. A.
Bibcode: 1986ApJ...309..435M
Altcode:
  Observations of the Fe XXI 1354.1 A line were obtained for several
  flares using the SMM-UVSP instrument with varying spectral and spatial
  resolution. Of special interest are spectral line profiles from the
  footpoints of flare loops taken during the impulsive phase. These
  data show blueshifted Fe XXI profiles coincident and cospatial with
  the impulsive brightening of chromospheric material. The present
  analysis supports the hypothesis that the blueshifted component of the
  high temperature emission is an integral part of the flare, possibly
  associated with chromospheric evaporation.

Title: Further atomic calculations for Fe XXIII
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1986A&A...155..413B
Altcode:
  Electron collision strengths for Fe XXIII have been obtained using the
  'distorted wave' approximation. Previous results (Bhatia and Mason,
  1981) were obtained including the configurations 2s(2), 2s2p, 2p(2),
  2s3s, 2s3p, and 2s3d. In this paper, the correlation configurations
  2p3s, 2p3p and 2p3d have also been included in the solution of the
  electron scattering problem.

Title: Electron Density Diagnostics in the 10--100 Angstrom Interval
    for a Solar Flare
Authors: Brown, W. A.; Bruner, M. E.; Acton, L. W.; Mason, H. E.
Bibcode: 1986ApJ...301..981B
Altcode:
  Electron density measurements from spectral-line diagnostics are
  reported for a solar flare on July 13, 1982, 1627 UT. The spectrogram,
  covering the 10-95 A interval, contained usable lines of helium-like
  ions C V, N VI, O VII, and Ne IX which are formed over the temperature
  interval 0.7-3.5 x 10 to the 6th K. In addition, spectral-line ratios of
  Si IX, Fe XIV, and Ca XV were compared with new theoretical estimates
  of their electron density sensitivity to obtain additional electron
  density diagnostics. An electron density of 3 x 10 to the 10th/cu
  cm was obtained. The comparison of these results from helium-like
  and other ions gives confidence in the utility of these tools for
  solar coronal analysis and will lead to a fuller understanding of the
  phenomena observed in this flare.

Title: Theoretical intensity ratios for the X-ray lines from CA XV
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1986A&A...155..417B
Altcode:
  Electron collision strengths for Ca XV have been obtained using
  the 'distorted wave' approximation. Previous results (Mason,
  1975; Dere et al., 1979) were obtained for the configurations
  2s<SUP>2</SUP>2p<SUP>2</SUP>, 2s2p<SUP>3</SUP>, 2p<SUP>4</SUP>. The
  authors present results for transitions 2s<SUP>2</SUP>2p<SUP>2</SUP>
  → 2s<SUP>2</SUP>2p3s, 2s<SUP>2</SUP>2p3d which give rise to lines
  in the X-ray spectra of solar active regions and flares.

Title: Interpretation of EUV spectra from loop structures in an
    active region at the limb
Authors: Doyle, J. G.; Mason, H. E.; Vernazza, J. E.
Bibcode: 1985A&A...150...69D
Altcode:
  EUV spectral scans and rasters of an active region observed at
  the limb are analyzed. These were obtained with the Harvard EUV
  spectroheliometer on the Apollo Telescope Mount. The spectra were
  taken following a small flare and an H-alpha surge. Diagnostic line
  ratios are used to determine electron densities and temperatures from
  the spectral scans. An electron pressure of 10 to the 15th/cu cm K
  is derived at 200,000 K. The temperatures derived from the diagnostic
  ratios indicate that the plasma is in ionization equilibrium, although
  mass flows of a few kilometers per s could be present. Rasters of
  the active region taken later show well defined loop structures. The
  parameters derived from the low temperature lines (100,000 K) and the
  rasters are inconsistent with those inferred from scaling laws based
  on static loop models. However, better agreement between the derived
  parameters and the models is achieved if use is made of the electron
  density derived from the emission measure of Mg X, and it is assumed
  that it remains constant up to 5-million K.

Title: Multiwavelength Analysis of a Well Observed Flare from Solar
    Maximum Mission
Authors: MacNeice, P.; Pallavicini, R.; Mason, H. E.; Simnett, G. M.;
   Antonucci, E.; Shine, R. A.; Rust, D. M.; Jordan, C.; Dennis, B. R.
Bibcode: 1985SoPh...99..167M
Altcode:
  We describe and analyse observations of an M1.4 flare which began at 17:
  00 UT on 12 November, 1980. Ground based Hα and magnetogram data have
  been combined with EUV, soft and hard X-ray observations made with
  instruments on-board the Solar Maximum Mission (SMM) satellite. The
  preflare phase was marked by a gradual brightening of the flare site
  in Ov and the disappearance of an Hα filament. Filament ejecta were
  seen in Ov moving southward at a speed of about 60 km s<SUP>−1</SUP>,
  before the impulsive phase. The flare loop footpoints brightened in Hα
  and the CaXIX resonance line broadened dramatically 2 min before the
  impulsive phase. Non-thermal hard X-ray emission was detected from the
  loop footpoints during the impulsive phase while during the same period
  blue-shifts corresponding to upflows of 200-250 km s<SUP>−1</SUP>
  were seen in Ca XIX. Evidence was found for energy deposition in both
  the chromosphere and corona at a number of stages during the flare. We
  consider two widely studied mechanisms for the production of the high
  temperature soft X-ray flare plasma in the corona, i.e. chromospheric
  evaporation, and a model in which the heating and transfer of material
  occurs between flux tubes during reconnection.

Title: Fe XIX transitions within the N = 2 complex
Authors: Loulergue, M.; Mason, H. E.; Nussbaumer, H.; Storey, P. J.
Bibcode: 1985A&A...150..246L
Altcode:
  The authors calculate the atomic data necessary for the interpretation
  of the Fe XIX spectra emitted by solar flare and tokamak plasmas. They
  consider the transitions between the 2s<SUP>2</SUP>2p<SUP>4</SUP>,
  2s2p<SUP>5</SUP>,and 2p<SUP>6</SUP> configurations. Some of the Fe
  XIX lines are potentially useful for determining electron density, and
  for one XUV flare spectrum they find evidence to indicate an electron
  density in excess of 10<SUP>13</SUP>cm<SUP>-3</SUP>.

Title: Flare Electron Densities Using X-ray Line Ratios
Authors: Brown, W. A.; Bruner, M. E.; Acton, L. W.; Mason, H. E.
Bibcode: 1985BAAS...17R.629B
Altcode:
  No abstract at ADS

Title: Diagnostic Application of Highly Ionised Iron Lines in the
    Extreme Ultraviolet Spectrum of a Solar Flare
Authors: Mason, H. E.; Bhatia, A. K.; Kastner, S. O.; Neupert, W. M.;
   Swartz, M.
Bibcode: 1984SoPh...92..199M
Altcode:
  Recent atomic data have been used to analyze a solar flare spectrum
  obtained with the Goddard Space Flight Center's grating spectrometer
  on the OSO-5 satellite. There exist in the wavelength region 90-200 Å
  strong lines from each of the ions Fe XVIII-Fe XXIV. The Fe XXI lines
  can be used as an electron density diagnostic for the 10<SUP>7</SUP>
  K plasma. From our analysis of a particular flare, we find a steep
  positive slope in the emission measure between 10<SUP>6.5</SUP> and
  10<SUP>7.2</SUP> K and an electron density of ∼4 × 10<SUP>11</SUP>
  cm<SUP>−3</SUP> at 10<SUP>7</SUP> K. We emphasise the need for high
  spectral and spatial resolution observations of solar flares in this
  wavelength region, which has to date been largely neglected.

Title: Evidence for Chromospheric Evaporation in Solar Flares from
    UV Observations
Authors: Shine, R. A.; Mason, H. E.
Bibcode: 1984BAAS...16..543S
Altcode:
  No abstract at ADS

Title: Atomic Calculations for the Highly Ionized Iron Ions Produced
    in Solar Flares
Authors: Mason, H. E.; Bhatia, A. K.
Bibcode: 1984uxsa.coll..141M
Altcode: 1984uxsa.conf..141M; 1984IAUCo..86..141M
  No abstract at ADS

Title: Atomic calculations for the Fe XX X-ray lines
Authors: Mason, H. E.; Bhatia, A. K.
Bibcode: 1983A&AS...52..181M
Altcode:
  The atomic data presented here and in Bhatia and Mason (1980) allow
  the calculation of theoretical intensity ratios for all the EUV, UV,
  and X-ray lines from Fe XX. Tabulations are presently given for the
  transitions between levels in the 2s2 2p3, 2s2 2p2 3s, and 2s2 2p2
  3d configurations of Fe(19+), and electron collision strengths are
  calculated by means of the 'distorted wave' approximation. In addition
  to the theoretical X-ray line intensity ratios, new spectral line
  identifications from a solar flare are presented.

Title: Atomic calculations for CA XVII - UV and X-ray lines
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1983A&AS...52..115B
Altcode:
  Doschek et al. (1977) have pointed out the importance of the Ca XVII
  UV lines as an electron density diagnostic. Energy levels, transition
  probabilities, and collision strengths, are presently obtained
  for the 2s2, 2s 2p, 2p2, 2s 3s, 2s 3p, and 2s 3d configurations
  of Ca XVII, and the theoretical intensity ratios for the UV and
  X-ray lines are compared with observed intensities in solar flare
  spectra. Inconsistencies are indicated in the analysis of UV data,
  and discrepancies between observed and theoretical intensity ratios
  indicate that further studies are required. New identifications are
  suggested in the X-ray wavelength region.

Title: Solar flare X-ray spectra from the Solar Maximum Mission Flat
    Crystal Spectrometer
Authors: Phillips, K. J. H.; Fawcett, B. C.; Kent, B. J.; Gabriel,
   A. H.; Leibacher, J. W.; Wolfson, C. J.; Acton, L. W.; Parkinson,
   J. H.; Culhane, J. L.; Mason, H. E.
Bibcode: 1982ApJ...256..774P
Altcode:
  High-resolution solar X-ray spectra obtained with the Flat Crystal
  Spectrometer aboard the Solar Maximum Mission from two solar flares and
  a nonflaring active region are analyzed. The 1-22 A region was observed
  during the flare on 1980 August 25, while smaller spectral regions were
  repeatedly covered during the 1980 November 5 flare. Voigt profiles
  were fitted to spectral lines to derive accurate wavelengths and to
  resolve blends. During the August 25 flare, 205 lines were found in
  the range 5.68-18.97 A, identifications being provided for all but 40
  (mostly weak) lines. Upper limits to flare densities are derived from
  various line ratios, the hotter (about 10 to the 7th K) ions giving an
  electron density of less than 10 to the 12th per cu cm for the August
  25 flare. Other observed line ratios (e.g., in Fe XVII and Mg XII)
  indicate a need for revisions in theoretical calculations.

Title: Solar physics
Authors: Gabriel, A. H.; Mason, H. E.
Bibcode: 1982aacp....1..345G
Altcode:
  A review is presented of the two major aspects of the interaction
  between atomic and solar physics. The first aspect is related to the way
  in which the various atomic collision processes determine the physical
  behavior of the plasma, and, thereby, the physical properties of the
  sun. The second aspect is concerned with diagnostics, taking into
  account the way in which the spectra emitted are determined by the
  atomic processes occurring in the observed plasma. Aspects of solar
  physics involving atomic collisions are examined, giving attention to
  radial structure, active regions, solar flares, element abundances,
  and spectroscopic diagnostics. Questions of impact excitation are
  considered along with ionization and recombination, absolute spectral
  intensities, and radiation effects.

Title: Solar Physics
Authors: Gabriel, Alan H.; Mason, Helen E.
Bibcode: 1982aacp....1..346G
Altcode:
  No abstract at ADS

Title: Atomic calculation for Fe XXIII, UV, and X-ray lines.
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1981A&A...103..324B
Altcode:
  Electron-ion scattering data have been obtained for the configurations
  2<SUP>2</SUP>, 2s2p, 2p<SUP>2</SUP>, 2s3s, 2s3p, and 2s3d of Fe
  XXIII in the "distorted wave" approximation. Oscillator and collision
  strengths are compared with other calculations. Wavelengths for various
  UV and X-ray lines are compared with laboratory measurements. New
  identifications are given for recent solar spectra based on intensity
  estimates. A line at 11.737 Å is identified as the strongest Fe XXIII
  line in the solar X-ray spectrum.

Title: Spectroscopic diagnostics of the active region: transition
    zone and corona.
Authors: Dere, K. P.; Mason, H. E.
Bibcode: 1981sars.work..129D
Altcode:
  Techniques currently used in the analysis of X-ray and UV spectroscopic
  data on solar features are reviewed with particular emphasis on
  those used for studies of active regions in the transition zone
  and corona. Attention is given to temperature and emission measure
  diagnostics by the use of line emission from a low-density plasma,
  broadband X-ray diagnostics, and diagnostics specific to various
  active region structures, and to electron density diagnostics based
  on metastable levels and the ratio of emission measure to the volume
  derived from spatially resolved images. Methods used for calculating
  atomic structure, electron and proton scattering, the ionization
  equilibrium and the effects on it of diffusion and flows, and the line
  profiles and optical depths are also considered.

Title: Atomic Data for the Interpretation of EUV Astrophysical Plasmas
Authors: Mason, H. E.
Bibcode: 1981ebas.conf...81M
Altcode:
  No abstract at ADS

Title: The Development of Flares Observed in the Spectral Lines OV
    1371 Å, FeXXI 1354 Å, and in Hard X-Rays
Authors: Woodgate, B. E.; Bruner, E. C.; Cheng, C. C.; Dennis, B. R.;
   Gurman, J. B.; Frost, K. J.; Hyder, C. L.; Kiplinger, A.; Mason,
   H. E.; Orwig, L. E.; Poland, A. I.; Schoolman, S. A.; Shine, R. A.;
   Tandberg-Hanssen, E. A.
Bibcode: 1980BAAS...12..911W
Altcode:
  No abstract at ADS

Title: Atomic data for Fe XXII
Authors: Mason, H. E.; Storey, P. J.
Bibcode: 1980MNRAS.191..631M
Altcode:
  Intermediate coupling energy levels, oscillator strengths and electron
  collision strengths in the distorted wave approximation have been
  computed for Fe XXII. Results are tabulated for the configurations
  2s22p, 2s 2p2, 2s23s, 2s23d, 2s 2p 3p, 2s24s, 2s24d, 2s 2p 4p. The
  level population of the excited level in the ground configuration is
  given as a function of electron density together with theoretical
  intensity ratios for the strongest transitions from the excited
  configurations. The theoretical results are compared to available
  solar flare observations. The intensity ratios observed correspond to
  electron densities of less than 10 to the 13 per cu cm.

Title: Theoretical atomic structure and electron scattering data
    for ions in the nitrogen isoelectronic sequence - MG VI, SI VIII,
    S X, A XII and CA XIV
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1980MNRAS.190..925B
Altcode:
  Intermediate coupling energy levels, oscillator strengths and
  electron collision strengths have been computed for the configurations
  2s<SUP>2</SUP>2p<SUP>3</SUP>, 2s2p<SUP>4</SUP> of Mg VI, Si VIII, S X,
  Ax II and Ca XIV. The electron scattering problem was solved using the
  "distorted wave" approximation. The statistical equilibrium equations
  for level populations were solved including all relevant excitation
  and de-excitation mechanisms. The level populations for the ground
  configuration and theoretical intensity ratios for the UV spectral
  lines are tabulated for conditions appropriate to the solar atmosphere.

Title: New atomic data for Fe/+19/
Authors: Bhatia, A. K.; Mason, H. E.
Bibcode: 1980A&A....83..380B
Altcode:
  New atomic data are tabulated for Fe(+19). The electron collision
  strengths are calculated using the 'distorted wave' approximation
  and results are presented for several energies of the exciting
  electron. The populations of the ground levels are calculated as a
  function of electron density under conditions appropriate to solar
  flares and tokamak plasmas. Theoretical intensity ratios are tabulated
  for the UV lines.

Title: EUV limb spectra of a surge observed from Skylab.
Authors: Doschek, G. A.; Feldman, U.; Mason, H. E.
Bibcode: 1979A&A....78..342D
Altcode:
  The EUV spectra of a surge observed at plus 8 in. and plus 20
  in. above the white light limb from Skylab are examined. The shape of
  the differential emission measure determined at 8 in. and 20 in. is
  nearly the same as for a quiet Sun spectrum at 8 in., but the emission
  measure of the surge at 8 in. is about an order of magnitude greater
  than for the quiet Sun. At 20 in. the emission measure of the surge is
  initially close to the quiet Sun distribution, but decreases by a factor
  of 4 within 6 min. The optically thin lines formed near 10 to the 5th
  power K show nonthermal broadening at 8 in., and electron densities near
  this temperature are derived from intersystem to resonance ratios. The
  volume of the emitting plasma at 8 in. above the limb was determined,
  concluding that a continuous energy input is required to explain the
  observations.

Title: XUV electron density diagnostics for solar flares.
Authors: Dere, K. P.; Mason, H. E.; Widing, K. G.; Bhatia, A. K.
Bibcode: 1979ApJS...40..341D
Altcode:
  Potential electron-density diagnostics for the high-temperature
  component of solar flares are studied with reference to the wavelength
  region from 171 to 630 A. The specific ions discussed include Fe
  IX through Fe XV, Ni XI through Ni XVII, and ions in the beryllium,
  boron, carbon, and nitrogen isoelectronic sequences. Line ratios that
  could be useful as density indicators under solar-flare conditions
  are indicated, available data for the ions considered are reviewed,
  and several theoretical intensity ratios are plotted. The results are
  employed to determine the electron-density distribution as a function
  of electron temperature for several spectra from two flares. For these
  flares it is found that the electron density increases from 10 billion
  to 500 billion per cu cm for a temperature increase from 1 million to
  10 million K.

Title: Fe XXI as an electron density diagnostic in solar flares.
Authors: Mason, H. E.; Bhatia, A. K.; Doschek, G. A.; Feldman, U.
Bibcode: 1979A&A....73...74M
Altcode:
  Atomic data have been calculated for Fe XXI, and the theoretical
  intensity ratios for many transitions are tabulated. Fe XXI lines in
  wavelength regions 1-25 A, 90-200 A, and 300-2500 A are discussed with
  reference to presently available solar and laboratory spectra. It is
  found that Fe XXI is an excellent density diagnostic for solar-flare
  and tokamak plasmas, when densities are in the range from 10 to the
  11th to 10 to the 15th per cu cm. The theoretical calculations are
  applied to flare spectra obtained from OSO 5, and an electron density
  of less than 10 to the 13th per cu cm is deduced for a temperature
  of 10,000,000 K. The results are somewhat ambiguous in several cases
  because of the limited spectral and temporal resolution of these
  earlier spectrometers. However, the calculations will be important
  for forthcoming solar projects, such as the Solar Maximum Mission.

Title: Electron densities in the solar corona from density-sensitive
    line ratios in the N I isoelectronic sequence.
Authors: Feldman, U.; Doschek, G. A.; Mariska, J. T.; Bhatia, A. K.;
   Mason, H. E.
Bibcode: 1978ApJ...226..674F
Altcode:
  Electron densities are derived in the solar inner corona from forbidden
  lines of S x near 1100 A. The density-sensitive line ratio considered
  is (4S0312-2D0312)/(4S0312-2D0612). The ratio is calculated as a
  function of density for four ions of the N I isoelectronic sequence,
  i.e., Mg VI, Si VIII, S x, and Ar XII. The variation of the ratio
  (4S0312-2P0312)/(4S0312-2D0312) with density is also calculated. The
  results are applied to off-limb spectra recorded by the NRL Skylab
  spectrograph. Densities were found to be the same in five quiet Sun
  regions and four active regions observed at heights &gt; 8" outside
  the white-light limb. The average density derived from the S x lines
  for all regions considered is 1.0 x 10 cm -3. This result applies to
  plasma at the temperature of formation of S x, i.e., 1.3 x 106 K. At
  heights greater than 20" outside the limb the average density is 7.7 x
  108 cm -3, and between 8" and 12" above the limb the average density is
  1.0 x 10 cm 3, for both quiet Sun and active regions. Subject heading:
  Sun: corona

Title: Density sensitivity of the solar EUV emission from boron-like
    ions.
Authors: Vernazza, J. E.; Mason, H. E.
Bibcode: 1978ApJ...226..720V
Altcode:
  The paper investigated the level populations and the line emission
  arising from ions of the boron isoelectronic sequence from C II to Ca
  XVI. It is found that, under conditions present in the solar corona,
  some of these ions have pairs of emission lines having intensity
  ratios which are density-sensitive. The boron-like lines observed in
  the solar spectrum between 300 and 1350 A are analyzed, and densities
  for quiet and active regions, coronal holes, sunspots, and flares
  are derived. Some aspects of the differences in the behavior of the
  emission from the lithium and boron sequences are also discussed.

Title: Densities in the quiet sun and polar coronal holes from EUV
    line ratios involving O III (1666.15 Å).
Authors: Doschek, G. A.; Feldman, U.; Bhatia, A. K.; Mason, H. E.
Bibcode: 1978ApJ...226.1129D
Altcode:
  The EUV line intensity ratios C iii (1908.73 A)/o iii (1666.15 A), 0 iii
  (1666.15 A)/Si iv (1402.77 A), and C iii (1908.73 A)ISi iv (1402.77 A)
  are shown to be sensitive to variations in the electron density at
  densities typical of the quiet Sun ( 1010 cm - at 6 x 10 K). Using
  the 0 iii line, the above ratios can be normalized to observational
  data and densities in quiet-Sun regions and coronal holes can be
  determined. The average value of the density determined for three
  quiet-Sun regions is 1.9 x 1010 cm - . The densities determined from
  several observations of the north and south polar coronal holes are
  about the same as in the quiet Sun, with the exception of one set of
  observations of the north polar hole that indicates a density about
  a factor of 2 less than that of the quiet Sun. Subject headings: Sun:
  corona - Sun: spectra - ultraviolet: spectra

Title: Theoretical intensity ratios for the UV lines of Mg VII,
    Si IX and S XI.
Authors: Mason, H. E.; Bhatia, A. K.
Bibcode: 1978MNRAS.184..423M
Altcode:
  Energy levels, oscillator strengths, and electron collision strengths
  have been computed for the configurations 2s2 2p2, 2s 2p3, 2p4 of Mg
  VII, Si IX, and S XI. Level populations for the ground configuration and
  theoretical intensity ratios for the UV lines are tabulated for electron
  densities and temperatures appropriate to the solar atmosphere. The
  identification of the Mg VII, Si IX, and S XI UV lines is discussed.

Title: Limb-brightening observations from the OSO-7
    satellite. III. Comparison of EUV line intensities of Fe XII, Fe XI,
    Fe XV, Si X and S XII, Si IX and S XI with predictions.
Authors: Kastner, S. O.; Mason, H. E.
Bibcode: 1978A&A....67..119K
Altcode:
  Continuing a study of heliocentric dependence of EUV emission line
  intensities observed by the Goddard OSO-7 spectroheliograph in 1972,
  the variation of lines of the ions Fe XII, Fe XI, Fe XV, Si X and S XII,
  Si IX and S XI is compared with the results of individual calculations
  for these ions, including theoretical intensities presented for Fe XII
  and Fe XI. Agreement is found to be good for Fe XII and reasonable
  for some of the lines of the other ions which in general are weaker
  in intensity. Several apparent anomalies are found however which may
  be due to unknown line components near the wavelengths observed.

Title: On the unidentified forbidden coronal lines.
Authors: Mason, H. E.; Nussbaumer, H.
Bibcode: 1977A&A....54..547M
Altcode:
  Approximately one quarter of the forbidden coronal lines observed
  in the visual and EUV regions of the solar spectrum are still
  unidentified. Evidence is presented showing that some of these
  unidentified lines originate from Fe X and Fe XI. Population densities
  of metastable levels in excited configurations of these ions are
  determined, and emissivities are calculated for transitions from these
  levels. Based on examination of emissivity ratios, it is proposed that
  the forbidden coronal lines observed at 4312, 3454, 1918.27, 1603.31,
  and 1428.76 be attributed to Fe X and that the lines at 5539, 4566,
  and 264 A be attributed to Fe XI.

Title: Density-Sensitive Lines in the EUV Region.
Authors: Vernazza, J. E.; Mason, H. E.
Bibcode: 1977uxsa.coll...15V
Altcode: 1977IAUCo..43...15V
  No abstract at ADS

Title: The interpretation of the forbidden emission lines from a
    coronal condensation.
Authors: Mason, H. E.
Bibcode: 1975MNRAS.171..119M
Altcode:
  Theoretical emission rates have recently been computed (Mason) for
  six lines observed in the visible spectrum of the solar corona. These
  rates are used to analyse the spectra of a coronal condensation
  observed by Lyot and Aly at the 1952 eclipse (Aly et al.). Average
  electron density and temperature conditions for the condensation are
  deduced and a specific model is proposed, in which electron density
  and temperature estimates are defined as a function of position within
  the condensation. Since continuum measurements were also recorded,
  abundance estimates for iron and calcium relative to hydrogen are
  obtained. The structure of the model is seen to be consistent with
  other solar observation.

Title: The excitation of several iron and calcium lines in the
    visible spectrum of the solar corona.
Authors: Mason, H. E.
Bibcode: 1975MNRAS.170..651M
Altcode:
  New atomic data have been obtained for the coronal ions Fe X, Fe
  XI, Fe XIV, Ca XII, Ca XIII and Ca XV, using a computer. Energy
  levels and radiative transition probabilities have been computed
  allowing for configuration interaction and relativistic effects. The
  electron scattering problem has been solved using the distorted
  wave approach. All radiative and collisional processes contributing
  to the equilibrium equations for the ground configuration were
  considered, including cascade via the excited configurations and the
  effect of autoionizing levels on the electron collisional excitation
  rate. Wherever possible, the accuracy of the atomic parameters has been
  estimated and the results compared to those of previous authors. The
  atomic data, level populations and emission rates for the ions studied,
  are tabulated for various physical conditions appropriate to the
  solar corona.

Title: The interpretation of the forbidden emission lines from a
    coronal condensation
Authors: Mason, Helen Elizabeth
Bibcode: 1974PhDT.......256M
Altcode:
  No abstract at ADS

Title: Spectrographic Examination of Chromatographic Columns
Authors: Dunabin, J. E.; Mason, H.; Seyfang, A. P.; Woodman, F. J.
Bibcode: 1949Natur.164..916D
Altcode:
  IN the determination of metallic traces, insufficient attention has been
  paid either to the advantages of direct spectrography of chromatographic
  columns, or to the chromatographic behaviour of organic metal complexes,
  although in the latter sphere the use of oxine<SUP>1</SUP> and of
  violuric acid<SUP>2</SUP> has been reported.

