Author name code: bonet
ADS astronomy entries on 2022-09-14
author:"Bonet, Jose Antonio" 
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Title: The Polarimetric and Helioseismic Imager on Solar Orbiter
Authors: Solanki, S. K.; del Toro Iniesta, J. C.; Woch, J.; Gandorfer,
   A.; Hirzberger, J.; Alvarez-Herrero, A.; Appourchaux, T.; Martínez
   Pillet, V.; Pérez-Grande, I.; Sanchis Kilders, E.; Schmidt, W.;
   Gómez Cama, J. M.; Michalik, H.; Deutsch, W.; Fernandez-Rico, G.;
   Grauf, B.; Gizon, L.; Heerlein, K.; Kolleck, M.; Lagg, A.; Meller, R.;
   Müller, R.; Schühle, U.; Staub, J.; Albert, K.; Alvarez Copano, M.;
   Beckmann, U.; Bischoff, J.; Busse, D.; Enge, R.; Frahm, S.; Germerott,
   D.; Guerrero, L.; Löptien, B.; Meierdierks, T.; Oberdorfer, D.;
   Papagiannaki, I.; Ramanath, S.; Schou, J.; Werner, S.; Yang, D.;
   Zerr, A.; Bergmann, M.; Bochmann, J.; Heinrichs, J.; Meyer, S.;
   Monecke, M.; Müller, M. -F.; Sperling, M.; Álvarez García, D.;
   Aparicio, B.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Cobos
   Carracosa, J. P.; Girela, F.; Hernández Expósito, D.; Herranz, M.;
   Labrousse, P.; López Jiménez, A.; Orozco Suárez, D.; Ramos, J. L.;
   Barandiarán, J.; Bastide, L.; Campuzano, C.; Cebollero, M.; Dávila,
   B.; Fernández-Medina, A.; García Parejo, P.; Garranzo-García, D.;
   Laguna, H.; Martín, J. A.; Navarro, R.; Núñez Peral, A.; Royo, M.;
   Sánchez, A.; Silva-López, M.; Vera, I.; Villanueva, J.; Fourmond,
   J. -J.; de Galarreta, C. Ruiz; Bouzit, M.; Hervier, V.; Le Clec'h,
   J. C.; Szwec, N.; Chaigneau, M.; Buttice, V.; Dominguez-Tagle, C.;
   Philippon, A.; Boumier, P.; Le Cocguen, R.; Baranjuk, G.; Bell,
   A.; Berkefeld, Th.; Baumgartner, J.; Heidecke, F.; Maue, T.; Nakai,
   E.; Scheiffelen, T.; Sigwarth, M.; Soltau, D.; Volkmer, R.; Blanco
   Rodríguez, J.; Domingo, V.; Ferreres Sabater, A.; Gasent Blesa,
   J. L.; Rodríguez Martínez, P.; Osorno Caudel, D.; Bosch, J.; Casas,
   A.; Carmona, M.; Herms, A.; Roma, D.; Alonso, G.; Gómez-Sanjuan, A.;
   Piqueras, J.; Torralbo, I.; Fiethe, B.; Guan, Y.; Lange, T.; Michel,
   H.; Bonet, J. A.; Fahmy, S.; Müller, D.; Zouganelis, I.
Bibcode: 2020A&A...642A..11S
Altcode: 2019arXiv190311061S
  <BR /> Aims: This paper describes the Polarimetric and Helioseismic
  Imager on the Solar Orbiter mission (SO/PHI), the first magnetograph and
  helioseismology instrument to observe the Sun from outside the Sun-Earth
  line. It is the key instrument meant to address the top-level science
  question: How does the solar dynamo work and drive connections between
  the Sun and the heliosphere? SO/PHI will also play an important role
  in answering the other top-level science questions of Solar Orbiter,
  while hosting the potential of a rich return in further science. <BR
  /> Methods: SO/PHI measures the Zeeman effect and the Doppler shift
  in the Fe I 617.3 nm spectral line. To this end, the instrument
  carries out narrow-band imaging spectro-polarimetry using a tunable
  LiNbO<SUB>3</SUB> Fabry-Perot etalon, while the polarisation modulation
  is done with liquid crystal variable retarders. The line and the nearby
  continuum are sampled at six wavelength points and the data are recorded
  by a 2k × 2k CMOS detector. To save valuable telemetry, the raw data
  are reduced on board, including being inverted under the assumption of
  a Milne-Eddington atmosphere, although simpler reduction methods are
  also available on board. SO/PHI is composed of two telescopes; one,
  the Full Disc Telescope, covers the full solar disc at all phases of
  the orbit, while the other, the High Resolution Telescope, can resolve
  structures as small as 200 km on the Sun at closest perihelion. The high
  heat load generated through proximity to the Sun is greatly reduced by
  the multilayer-coated entrance windows to the two telescopes that allow
  less than 4% of the total sunlight to enter the instrument, most of
  it in a narrow wavelength band around the chosen spectral line. <BR />
  Results: SO/PHI was designed and built by a consortium having partners
  in Germany, Spain, and France. The flight model was delivered to
  Airbus Defence and Space, Stevenage, and successfully integrated into
  the Solar Orbiter spacecraft. A number of innovations were introduced
  compared with earlier space-based spectropolarimeters, thus allowing
  SO/PHI to fit into the tight mass, volume, power and telemetry budgets
  provided by the Solar Orbiter spacecraft and to meet the (e.g. thermal)
  challenges posed by the mission's highly elliptical orbit.

Title: SOPHISM: Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
   Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
   Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
Bibcode: 2018ascl.soft10017B
Altcode:
  SOPHISM models astronomical instrumentation from the entrance
  of the telescope to data acquisition at the detector, along with
  software blocks dealing with, for example, demodulation, inversion,
  and compression. The code performs most analyses done with light
  in astronomy, such as differential photometry, spectroscopy, and
  polarimetry. The simulator offers flexibility and implementation of new
  effects and subsystems, making it user-adaptable for a wide variety
  of instruments. SOPHISM can be used for all stages of instrument
  definition, design, operation, and lifetime tracking evaluation.

Title: SOPHISM: An End-to-end Software Instrument Simulator
Authors: Blanco Rodríguez, J.; del Toro Iniesta, J. C.; Orozco
   Suárez, D.; Martínez Pillet, V.; Bonet, J. A.; Feller, A.;
   Hirzberger, J.; Lagg, A.; Piqueras, J.; Gasent Blesa, J. L.
Bibcode: 2018ApJS..237...35B
Altcode:
  We present a software simulator for the modeling of astronomical
  instrumentation, which includes platform effects and software
  processing. It is an end-to-end simulator, from the entrance of
  the telescope to the data acquisition at the detector, along with
  software blocks dealing, e.g., with demodulation, inversion, and
  compression. Developed following the Solar Orbiter/Polarimetric
  and Helioseismic Imager (SO/PHI) instrument, it comprises elements
  such as a filtergraph, polarimetric modulator, detector, vibrations,
  and accumulations. Through these, the simulator performs most of the
  analyses that can be done with light in astronomy, such as differential
  photometry, spectroscopy, and polarimetry. The simulator is coded
  with high flexibility and ease of implementation of new effects and
  subsystems. Thus, it allows for the user to adapt it to a wide variety
  of instruments, even not exclusively solar ones, as illustrated with
  an example of application to a night-time observation. The simulator
  can provide support in the phase of instrument design and help assess
  tolerances and test solutions to underperformances arising during the
  instrument operations. All this makes SOPHISM a very valuable tool
  for all the stages of astronomical instrument definition, design,
  operation, and lifetime tracking evaluation.

Title: The History of a Quiet-Sun Magnetic Element Revealed by
    IMaX/SUNRISE
Authors: Requerey, Iker S.; Del Toro Iniesta, Jose Carlos; Bellot
   Rubio, Luis R.; Bonet, José A.; Martínez Pillet, Valentín; Solanki,
   Sami K.; Schmidt, Wolfgang
Bibcode: 2014ApJ...789....6R
Altcode: 2014arXiv1405.2837R
  Isolated flux tubes are considered to be fundamental magnetic building
  blocks of the solar photosphere. Their formation is usually attributed
  to the concentration of magnetic field to kG strengths by the convective
  collapse mechanism. However, the small size of the magnetic elements in
  quiet-Sun areas has prevented this scenario from being studied in fully
  resolved structures. Here, we report on the formation and subsequent
  evolution of one such photospheric magnetic flux tube, observed in
  the quiet Sun with unprecedented spatial resolution (0.''15-0.''18)
  and high temporal cadence (33 s). The observations were acquired by
  the Imaging Magnetograph eXperiment on board the SUNRISE balloon-borne
  solar observatory. The equipartition field strength magnetic element
  is the result of the merging of several same polarity magnetic flux
  patches, including a footpoint of a previously emerged loop. The
  magnetic structure is then further intensified to kG field strengths
  by convective collapse. The fine structure found within the flux
  concentration reveals that the scenario is more complex than can be
  described by a thin flux tube model with bright points and downflow
  plumes being established near the edges of the kG magnetic feature. We
  also observe a daisy-like alignment of surrounding granules and a
  long-lived inflow toward the magnetic feature. After a subsequent
  weakening process, the field is again intensified to kG strengths. The
  area of the magnetic feature is seen to change in anti-phase with the
  field strength, while the brightness of the bright points and the speed
  of the downflows varies in phase. We also find a relation between the
  brightness of the bright point and the presence of upflows within it.

Title: The power spectrum of solar convection flows from
    high-resolution observations and 3D simulations
Authors: Yelles Chaouche, L.; Moreno-Insertis, F.; Bonet, J. A.
Bibcode: 2014A&A...563A..93Y
Altcode: 2014arXiv1402.2293Y
  Context. Understanding solar surface magnetoconvection requires
  the study of the Fourier spectra of the velocity fields. Nowadays,
  observations are available that resolve very small spatial scales,
  well into the subgranular range, almost reaching the scales routinely
  resolved in numerical magnetoconvection simulations. Comparison of
  numerical and observational data at present can provide an assessment
  of the validity of the observational proxies. <BR /> Aims: Our aims are:
  (1) to obtain Fourier spectra for the photospheric velocity fields using
  the spectropolarimetric observations with the highest spatial resolution
  so far (~120 km), thus reaching for the first time spatial scales well
  into the subgranular range; (2) to calculate corresponding Fourier
  spectra from realistic 3D numerical simulations of magnetoconvection
  and carry out a proper comparison with their observational counterparts
  considering the residual instrumental degradation in the observational
  data; and (3) to test the observational proxies on the basis of
  the numerical data alone, by comparing the actual velocity field
  in the simulations with synthetic observations obtained from the
  numerical boxes. <BR /> Methods: (a) For the observations, data from
  the SUNRISE/IMaX spectropolarimeter are used. (b) For the simulations,
  we use four series of runs obtained with the STAGGER code for different
  average signed vertical magnetic field values (0, 50, 100, and 200
  G). Spectral line profiles are synthesized from the numerical boxes for
  the same line observed by IMaX (Fe I 5250.2 Å) and degraded to match
  the performance of the IMaX instrument. Proxies for the velocity field
  are obtained via Dopplergrams (vertical component) and local correlation
  tracking (LCT, for the horizontal component). Fourier power spectra are
  calculated and a comparison between the synthetic and observational data
  sets carried out. (c) For the internal comparison of the numerical data,
  velocity values on constant optical depth surfaces are used instead
  of on horizontal planes. <BR /> Results: A very good match between
  observational and simulated Fourier power spectra is obtained for the
  vertical velocity data for scales between 200 km and 6 Mm. Instead,
  a clear vertical shift is obtained when the synthetic observations are
  not degraded to emulate the degradation in the IMaX data. The match
  for the horizontal velocity data is much less impressive because
  of the inaccuracies of the LCT procedure. Concerning the internal
  comparison of the direct velocity values of the numerical boxes with
  those from the synthetic observations, a high correlation (0.96) is
  obtained for the vertical component when using the velocity values on
  the log τ<SUB>500</SUB> = -1 surface in the box. The corresponding
  Fourier spectra are near each other. A lower maximum correlation (0.5)
  is reached (at log τ<SUB>500</SUB> = 0) for the horizontal velocities
  as a result of the coarseness of the LCT procedure. Correspondingly,
  the Fourier spectra for the LCT-determined velocities is well below that
  from the actual velocity components. <BR /> Conclusions: As measured
  by the Fourier spectra, realistic numerical simulations of surface
  magnetoconvection provide a very good match to the observational
  proxies for the photospheric velocity fields at least on scales from
  several Mm down to around 200 km. Taking into account the spatial and
  spectral instrumental blurring is essential for the comparison between
  simulations and observations. Dopplergrams are an excellent proxy for
  the vertical velocities on constant-τ isosurfaces, while LCT is a
  much less reliable method of determining the horizontal velocities.

Title: Time evolution of a single, quiet-Sun magnetic structure
Authors: Requerey, Iker S.; Bonet, José Antonio; Solanki, Sami K.;
   Bellot Rubio, L. R.; Del Toro Iniesta, Jose Carlos
Bibcode: 2014cosp...40E2828R
Altcode:
  Isolated flux tubes are considered to be fundamental magnetic building
  blocks of the solar photosphere. Their formation is usually attributed
  to the concentration of magnetic field to kG strengths by the convective
  instability mechanism. However, the small size of the magnetic elements
  in quiet-Sun areas has prevented this scenario from being studied
  in fully resolved structures. Here we report on the formation and
  subsequent evolution of a photospheric magnetic flux tube, observed
  in the quiet Sun with unprecedented spatial resolution (0. ('') 15 -
  0. ('') 18) and high temporal cadence (33 s). The observations were
  acquired by the Imaging Magnetograph Experiment (IMaX) aboard the
  textsc{Sunrise} balloon-borne solar observatory. The equipartition
  field strength magnetic element is reached from the merging of
  several magnetic flux patches in a mesogranule-sized sink. The
  magnetic structure is then further intensified to kG field strengths by
  convective collapse and granular compression. The fine structure found
  within the flux concentration reveal that the scenario is more complex
  than a canonical flux tube model. After a subsequent weakening process,
  the field is further intensified to kG strengths. Seen as a whole, the
  evolution of the magnetic structure is compatible with oscillations in
  all basic physical quantities. A discussion on whether this evolution
  fits to the current theoretical descriptions is also presented.

Title: Is Magnetic Reconnection the Cause of Supersonic Upflows in
    Granular Cells?
Authors: Borrero, J. M.; Martínez Pillet, V.; Schmidt, W.; Quintero
   Noda, C.; Bonet, J. A.; del Toro Iniesta, J. C.; Bellot Rubio, L. R.
Bibcode: 2013ApJ...768...69B
Altcode: 2013arXiv1303.2557B
  In a previous work, we reported on the discovery of supersonic magnetic
  upflows on granular cells in data from the SUNRISE/IMaX instrument. In
  the present work, we investigate the physical origin of these events
  employing data from the same instrument but with higher spectral
  sampling. By means of the inversion of Stokes profiles we are able
  to recover the physical parameters (temperature, magnetic field,
  line-of-sight velocity, etc.) present in the solar photosphere at the
  time of these events. The inversion is performed in a Monte-Carlo-like
  fashion, that is, repeating it many times with different initializations
  and retaining only the best result. We find that many of the events are
  characterized by a reversal in the polarity of the magnetic field along
  the vertical direction in the photosphere, accompanied by an enhancement
  in the temperature and by supersonic line-of-sight velocities. In
  about half of the studied events, large blueshifted and redshifted
  line-of-sight velocities coexist above/below each other. These features
  can be explained in terms of magnetic reconnection, where the energy
  stored in the magnetic field is released in the form of kinetic
  and thermal energy when magnetic field lines of opposite polarities
  coalesce. However, the agreement with magnetic reconnection is not
  perfect and, therefore, other possible physical mechanisms might also
  play a role.

Title: Study of small magnetic structures in the solar photosphere
Authors: Cabello, I.; Domingo, V.; Bonet, J. A.; Blanco Rodríguez,
   J.; Balmaceda, L. A.
Bibcode: 2013hsa7.conf..805C
Altcode:
  The study of small scale magnetic structures in the solar photosphere
  is of great relevance for the understanding of the global behaviour of
  the Sun. Because of the small spatial and temporal scales involved, the
  use of high resolution images and fast cadence is fundamental for their
  study. In order to obtain such images, sophisticated computational
  techniques that compensate for the atmospheric degradation and
  telescope aberration have been developed, improving in this way the
  spatial resolution. In this work, we use G-band images obtained with
  the 1 m-Swedish Solar Telescope located at La Palma (Canary Islands,
  Spain). The images have been restored with MOMFBD (Multi-Object
  Multi-Frame Blind Deconvolution), a technique that combines multiple
  images acquired in a short time interval. The resulting images have
  a resolution close to the diffraction limit of the telescope (0.1
  arcsec) allowing the study of very small bright structures present
  in the inter-granular lanes in the solar photosphere, known as Bright
  Points. It is highlighted the great presence of magnetic structures in
  quiet Sun regions analyzed from different observational campaigns. The
  density of BPs in the quiet Sun shows a decrease as we approach the
  limb, with values of ≃q 1% at the centre (μ ≈ 1), and ≃q 0.2%
  at μ ≈ 0.3. We also present the discovery of small vortexes detected
  in the solar surface through the movement of BPs, with radii around 241
  km and lifetimes longer than 5 minutes. Further analyses, comprising
  longer time series and information from different solar layers, are
  being performed aiming at a more in-depth knowledge of these phenomena.

Title: First Results from the SUNRISE Mission
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.;
   Gandorfer, A.; Hirzberger, J.; Jafarzadeh, S.; Lagg, A.; Riethmüller,
   T. L.; Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; González,
   M. J. M.; Pillet, V. M.; Khomenko, E.; Yelles Chaouche, L.; Iniesta,
   J. C. d. T.; Domingo, V.; Palacios, J.; Knölker, M.; González,
   N. B.; Borrero, J. M.; Berkefeld, T.; Franz, M.; Roth, M.; Schmidt,
   W.; Steiner, O.; Title, A. M.
Bibcode: 2012ASPC..455..143S
Altcode:
  The SUNRISE balloon-borne solar observatory consists of a 1m aperture
  Gregory telescope, a UV filter imager, an imaging vector polarimeter,
  an image stabilization system, and further infrastructure. The first
  science flight of SUNRISE yielded high-quality data that reveal the
  structure, dynamics, and evolution of solar convection, oscillations,
  and magnetic fields at a resolution of around 100 km in the quiet
  Sun. Here we describe very briefly the mission and the first results
  obtained from the SUNRISE data, which include a number of discoveries.

Title: Detection of Vortex Tubes in Solar Granulation from
    Observations SUNRISE
Authors: Steiner, O.; Franz, M.; González, N. B.; Nutto, C.; Rezaei,
   R.; Pillet, V. M.; Bonet, J. A.; Iniesta, J. C. d. T.; Domingo, V.;
   Solanki, S. K.; Knölker, M.; Schmidt, W.; Barthol, P.; Gandorfer, A.
Bibcode: 2012ASPC..455...35S
Altcode:
  We investigated a time series of continuum intensity maps and
  Dopplergrams of granulation in a very quiet solar region at the disk
  center, recorded with the Imaging Magnetograph eXperiment (IMaX)
  on board the balloon-borne solar observatory SUNRISE. We find that
  granules frequently show substructure in the form of lanes composed of
  a leading bright rim and a trailing dark edge, which move together
  from the boundary of a granule into the granule itself. We find
  strikingly similar events in synthesized intensity maps from an ab
  initio numerical simulation of solar surface convection. We conclude
  that these granular lanes are the visible signature of (horizontally
  oriented) vortex tubes. The characteristic optical appearance of vortex
  tubes at the solar surface is explained. This paper is a summary and
  update of the results previously presented in Steiner et al. (2010).

Title: Supersonic Magnetic Flows in the Quiet Sun Observed with
    SUNRISE/IMaX
Authors: Borrero, J. M.; Pillet, V. M.; Schlichenmaier, R.; Schmidt,
   W.; Berkefeld, T.; Solanki, S. K.; Bonet, J. A.; Iniesta, J. C. d. T.;
   Domingo, V.; Barthol, P.; Gandorfer, A.
Bibcode: 2012ASPC..455..155B
Altcode: 2012arXiv1202.4354B
  In this contribution we describe some recent observations of high-speed
  magnetized flows in the quiet Sun granulation. These observations
  were carried out with the Imaging Magnetograph eXperiment (IMaX)
  onboard the stratospheric balloon SUNRISE, and possess an unprecedented
  spatial resolution and temporal cadence. These flows were identified as
  highly shifted circular polarization (Stokes V) signals. We estimate
  the LOS velocity responsible for these shifts to be larger than 6 km
  s<SUP>-1</SUP>, and therefore we refer to them as supersonic magnetic
  flows. The average lifetime of the detected events is 81.3 s and
  they occupy an average area of about 23 000 km<SUP>2</SUP>. Most of
  the events occur within granular cells and correspond therefore to
  upflows. However some others occur in intergranular lanes or bear no
  clear relation to the convective velocity pattern. We analyze a number
  of representative examples and discuss them in terms of magnetic loops,
  reconnection events, and convective collapse.

Title: Center-to-limb variation of the area covered by magnetic
    bright points in the quiet Sun
Authors: Bonet, J. A.; Cabello, I.; Sánchez Almeida, J.
Bibcode: 2012A&A...539A...6B
Altcode: 2011arXiv1112.2513B
  Context. The quiet Sun magnetic fields produce ubiquitous bright points
  (BPs) that cover a significant fraction of the solar surface. Their
  contribution to the total solar irradiance (TSI) is so-far unknown. <BR
  /> Aims: We aim at measuring the center-to-limb variation (CLV) of
  the fraction of solar surface covered by quiet Sun magnetic bright
  points. The fraction is referred to as the fraction of covered
  surface (FCS). <BR /> Methods: We count the area covered by BPs in
  G-band images obtained at various heliocentric angles with the 1-m
  Swedish Solar Telescope on La Palma. We restore the images to bring
  them close to the diffraction limit of the instrument (~0'.1). <BR />
  Results: The FCS is largest at the disk center (≃1%), and then drops
  down to become ≃0.2% at μ ≃ 0.3 (where μ is the cosine of the
  heliocentric angle). The relationship has a large scatter, which we
  evaluate by comparing different subfields within our FOVs. We develop
  a toy-model to describe the observed CLV, which considers the BPs as
  depressions in the mean solar photosphere characterized by a depth,
  a width, and a spread in the inclinations. Although the model is
  poorly constrained by observations, it shows the BPs to be shallow
  structures (depth &lt; width) with a large range of inclinations. We
  also estimate how different parts of the solar disk may contribute to
  the TSI variations, finding that 90% is contributed by BPs with μ &gt;
  0.5, and half of it is due to BPs with μ &gt; 0.8.

Title: The Frontier between Small-scale Bipoles and Ephemeral Regions
in the Solar Photosphere: Emergence and Decay of an Intermediate-scale
    Bipole Observed with SUNRISE/IMaX
Authors: Guglielmino, S. L.; Martínez Pillet, V.; Bonet, J. A.;
   del Toro Iniesta, J. Carlos; Bellot Rubio, L. R.; Solanki, S. K.;
   Schmidt, W.; Gandorfer, A.; Barthol, P.; Knölker, M.
Bibcode: 2012ApJ...745..160G
Altcode: 2011arXiv1110.1405G
  We report on the photospheric evolution of an intermediate-scale (≈4
  Mm footpoint separation) magnetic bipole, from emergence to decay,
  observed in the quiet Sun at high spatial (0farcs3) and temporal (33 s)
  resolution. The observations were acquired by the Imaging Magnetograph
  Experiment imaging magnetograph during the first science flight of the
  SUNRISE balloon-borne solar observatory. The bipole flux content is 6 ×
  10<SUP>17</SUP> Mx, representing a structure bridging the gap between
  granular scale bipoles and the smaller ephemeral regions. Footpoints
  separate at a speed of 3.5 km s<SUP>-1</SUP> and reach a maximum
  distance of 4.5 Mm before the field dissolves. The evolution of the
  bipole is revealed to be very dynamic: we found a proper motion of
  the bipole axis and detected a change of the azimuth angle of 90° in
  300 s, which may indicate the presence of some writhe in the emerging
  structure. The overall morphology and behavior are in agreement with
  previous analyses of bipolar structures emerging at the granular scale,
  but we also found several similarities with emerging flux structures
  at larger scales. The flux growth rate is 2.6 × 10<SUP>15</SUP> Mx
  s<SUP>-1</SUP>, while the mean decay rate is one order of magnitude
  smaller. We describe in some detail the decay phase of the bipole
  footpoints that includes break up into smaller structures, and
  interaction with preexisting fields leading to cancellation, but it
  appears to be dominated by an as-yet unidentified diffusive process
  that removes most of the flux with an exponential flux decay curve. The
  diffusion constant (8 × 10<SUP>2</SUP> km<SUP>2</SUP> s<SUP>-1</SUP>)
  associated with this decay is similar to the values used to describe
  the large-scale diffusion in flux transport models.

Title: Magnetic field emergence in mesogranular-sized exploding
    granules observed with sunrise/IMaX data
Authors: Palacios, J.; Blanco Rodríguez, J.; Vargas Domínguez, S.;
   Domingo, V.; Martínez Pillet, V.; Bonet, J. A.; Bellot Rubio, L. R.;
   Del Toro Iniesta, J. C.; Solanki, S. K.; Barthol, P.; Gandorfer, A.;
   Berkefeld, T.; Schmidt, W.; Knölker, M.
Bibcode: 2012A&A...537A..21P
Altcode: 2011arXiv1110.4555P
  We report on magnetic field emergences covering significant
  areas of exploding granules. The balloon-borne mission Sunrise
  provided high spatial and temporal resolution images of the solar
  photosphere. Continuum images, longitudinal and transverse magnetic
  field maps and Dopplergrams obtained by IMaX onboard Sunrise are
  analyzed by local correlation traking (LCT), divergence calculation
  and time slices, Stokes inversions and numerical simulations are also
  employed. We characterize two mesogranular-scale exploding granules
  where ~10<SUP>18</SUP> Mx of magnetic flux emerges. The emergence
  of weak unipolar longitudinal fields (~100 G) start with a single
  visible magnetic polarity, occupying their respective granules' top
  and following the granular splitting. After a while, mixed polarities
  start appearing, concentrated in downflow lanes. The events last around
  20 min. LCT analyses confirm mesogranular scale expansion, displaying
  a similar pattern for all the physical properties, and divergence
  centers match between all of them. We found a similar behaviour
  with the emergence events in a numerical MHD simulation. Granule
  expansion velocities are around 1 kms<SUP>-1</SUP> while magnetic
  patches expand at 0.65 kms<SUP>-1</SUP>. One of the analyzed events
  evidences the emergence of a loop-like structure. Advection of
  the emerging magnetic flux features is dominated by convective
  motion resulting from the exploding granule due to the magnetic
  field frozen in the granular plasma. Intensification of the
  magnetic field occurs in the intergranular lanes, probably
  because of being directed by the downflowing plasma. <P />Movies
  associated to Figs. 2-4 are available in electronic form at <A
  href="http://www.aanda.org">http://www.aanda.org</A>

Title: The Sun at high resolution: first results from the Sunrise
    mission
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller,
   A.; Gandorfer, A.; Hirzberger, J.; Lagg, A.; Riethmüller, T. L.;
   Schüssler, M.; Wiegelmann, T.; Bonet, J. A.; Pillet, V. Martínez;
   Khomenko, E.; del Toro Iniesta, J. C.; Domingo, V.; Palacios, J.;
   Knölker, M.; González, N. Bello; Borrero, J. M.; Berkefeld, T.;
   Franz, M.; Roth, M.; Schmidt, W.; Steiner, O.; Title, A. M.
Bibcode: 2011IAUS..273..226S
Altcode:
  The Sunrise balloon-borne solar observatory consists of a 1m aperture
  Gregory telescope, a UV filter imager, an imaging vector polarimeter,
  an image stabilization system and further infrastructure. The first
  science flight of Sunrise yielded high-quality data that reveal the
  structure, dynamics and evolution of solar convection, oscillations
  and magnetic fields at a resolution of around 100 km in the quiet
  Sun. Here we describe very briefly the mission and the first results
  obtained from the Sunrise data, which include a number of discoveries.

Title: Mesogranulation and the Solar Surface Magnetic Field
    Distribution
Authors: Yelles Chaouche, L.; Moreno-Insertis, F.; Martínez Pillet,
   V.; Wiegelmann, T.; Bonet, J. A.; Knölker, M.; Bellot Rubio, L. R.;
   del Toro Iniesta, J. C.; Barthol, P.; Gandorfer, A.; Schmidt, W.;
   Solanki, S. K.
Bibcode: 2011ApJ...727L..30Y
Altcode: 2010arXiv1012.4481Y
  The relation of the solar surface magnetic field with mesogranular
  cells is studied using high spatial (≈100 km) and temporal (≈30
  s) resolution data obtained with the IMaX instrument on board
  SUNRISE. First, mesogranular cells are identified using Lagrange
  tracers (corks) based on horizontal velocity fields obtained through
  local correlation tracking. After ≈20 minutes of integration, the
  tracers delineate a sharp mesogranular network with lanes of width
  below about 280 km. The preferential location of magnetic elements in
  mesogranular cells is tested quantitatively. Roughly 85% of pixels with
  magnetic field higher than 100 G are located in the near neighborhood
  of mesogranular lanes. Magnetic flux is therefore concentrated in
  mesogranular lanes rather than intergranular ones. Second, magnetic
  field extrapolations are performed to obtain field lines anchored in
  the observed flux elements. This analysis, therefore, is independent
  of the horizontal flows determined in the first part. A probability
  density function (PDF) is calculated for the distribution of distances
  between the footpoints of individual magnetic field lines. The PDF has
  an exponential shape at scales between 1 and 10 Mm, with a constant
  characteristic decay distance, indicating the absence of preferred
  convection scales in the mesogranular range. Our results support
  the view that mesogranulation is not an intrinsic convective scale
  (in the sense that it is not a primary energy-injection scale of solar
  convection), but also give quantitative confirmation that, nevertheless,
  the magnetic elements are preferentially found along mesogranular lanes.

Title: The Imaging Magnetograph eXperiment (IMaX) for the Sunrise
    Balloon-Borne Solar Observatory
Authors: Martínez Pillet, V.; del Toro Iniesta, J. C.;
   Álvarez-Herrero, A.; Domingo, V.; Bonet, J. A.; González Fernández,
   L.; López Jiménez, A.; Pastor, C.; Gasent Blesa, J. L.; Mellado, P.;
   Piqueras, J.; Aparicio, B.; Balaguer, M.; Ballesteros, E.; Belenguer,
   T.; Bellot Rubio, L. R.; Berkefeld, T.; Collados, M.; Deutsch, W.;
   Feller, A.; Girela, F.; Grauf, B.; Heredero, R. L.; Herranz, M.;
   Jerónimo, J. M.; Laguna, H.; Meller, R.; Menéndez, M.; Morales, R.;
   Orozco Suárez, D.; Ramos, G.; Reina, M.; Ramos, J. L.; Rodríguez,
   P.; Sánchez, A.; Uribe-Patarroyo, N.; Barthol, P.; Gandorfer, A.;
   Knoelker, M.; Schmidt, W.; Solanki, S. K.; Vargas Domínguez, S.
Bibcode: 2011SoPh..268...57M
Altcode: 2010SoPh..tmp..181M; 2010arXiv1009.1095M
  The Imaging Magnetograph eXperiment (IMaX) is a spectropolarimeter
  built by four institutions in Spain that flew on board the Sunrise
  balloon-borne solar observatory in June 2009 for almost six days over
  the Arctic Circle. As a polarimeter, IMaX uses fast polarization
  modulation (based on the use of two liquid crystal retarders),
  real-time image accumulation, and dual-beam polarimetry to reach
  polarization sensitivities of 0.1%. As a spectrograph, the instrument
  uses a LiNbO<SUB>3</SUB> etalon in double pass and a narrow band
  pre-filter to achieve a spectral resolution of 85 mÅ. IMaX uses the
  high-Zeeman-sensitive line of Fe I at 5250.2 Å and observes all four
  Stokes parameters at various points inside the spectral line. This
  allows vector magnetograms, Dopplergrams, and intensity frames to be
  produced that, after reconstruction, reach spatial resolutions in the
  0.15 - 0.18 arcsec range over a 50×50 arcsec field of view. Time
  cadences vary between 10 and 33 s, although the shortest one only
  includes longitudinal polarimetry. The spectral line is sampled in
  various ways depending on the applied observing mode, from just two
  points inside the line to 11 of them. All observing modes include
  one extra wavelength point in the nearby continuum. Gauss equivalent
  sensitivities are 4 G for longitudinal fields and 80 G for transverse
  fields per wavelength sample. The line-of-sight velocities are estimated
  with statistical errors of the order of 5 - 40 m s<SUP>−1</SUP>. The
  design, calibration, and integration phases of the instrument,
  together with the implemented data reduction scheme, are described in
  some detail.

Title: The Sunrise Mission
Authors: Barthol, P.; Gandorfer, A.; Solanki, S. K.; Schüssler,
   M.; Chares, B.; Curdt, W.; Deutsch, W.; Feller, A.; Germerott, D.;
   Grauf, B.; Heerlein, K.; Hirzberger, J.; Kolleck, M.; Meller, R.;
   Müller, R.; Riethmüller, T. L.; Tomasch, G.; Knölker, M.; Lites,
   B. W.; Card, G.; Elmore, D.; Fox, J.; Lecinski, A.; Nelson, P.;
   Summers, R.; Watt, A.; Martínez Pillet, V.; Bonet, J. A.; Schmidt,
   W.; Berkefeld, T.; Title, A. M.; Domingo, V.; Gasent Blesa, J. L.;
   del Toro Iniesta, J. C.; López Jiménez, A.; Álvarez-Herrero, A.;
   Sabau-Graziati, L.; Widani, C.; Haberler, P.; Härtel, K.; Kampf,
   D.; Levin, T.; Pérez Grande, I.; Sanz-Andrés, A.; Schmidt, E.
Bibcode: 2011SoPh..268....1B
Altcode: 2010arXiv1009.2689B; 2010SoPh..tmp..224B
  The first science flight of the balloon-borne Sunrise telescope took
  place in June 2009 from ESRANGE (near Kiruna/Sweden) to Somerset
  Island in northern Canada. We describe the scientific aims and
  mission concept of the project and give an overview and a description
  of the various hardware components: the 1-m main telescope with its
  postfocus science instruments (the UV filter imager SuFI and the imaging
  vector magnetograph IMaX) and support instruments (image stabilizing
  and light distribution system ISLiD and correlating wavefront sensor
  CWS), the optomechanical support structure and the instrument mounting
  concept, the gondola structure and the power, pointing, and telemetry
  systems, and the general electronics architecture. We also explain
  the optimization of the structural and thermal design of the complete
  payload. The preparations for the science flight are described,
  including AIV and ground calibration of the instruments. The course
  of events during the science flight is outlined, up to the recovery
  activities. Finally, the in-flight performance of the instrumentation
  is discussed.

Title: The Filter Imager SuFI and the Image Stabilization and Light
Distribution System ISLiD of the Sunrise Balloon-Borne Observatory:
    Instrument Description
Authors: Gandorfer, A.; Grauf, B.; Barthol, P.; Riethmüller, T. L.;
   Solanki, S. K.; Chares, B.; Deutsch, W.; Ebert, S.; Feller, A.;
   Germerott, D.; Heerlein, K.; Heinrichs, J.; Hirche, D.; Hirzberger,
   J.; Kolleck, M.; Meller, R.; Müller, R.; Schäfer, R.; Tomasch,
   G.; Knölker, M.; Martínez Pillet, V.; Bonet, J. A.; Schmidt, W.;
   Berkefeld, T.; Feger, B.; Heidecke, F.; Soltau, D.; Tischenberg, A.;
   Fischer, A.; Title, A.; Anwand, H.; Schmidt, E.
Bibcode: 2011SoPh..268...35G
Altcode: 2010SoPh..tmp..176G; 2010arXiv1009.1037G
  We describe the design of the Sunrise Filter Imager (SuFI) and the
  Image Stabilization and Light Distribution (ISLiD) unit onboard the
  Sunrise balloon borne solar observatory. This contribution provides the
  necessary information which is relevant to understand the instruments'
  working principles, the relevant technical data, and the necessary
  information about calibration issues directly related to the science
  data.

Title: SUNRISE: Instrument, Mission, Data, and First Results
Authors: Solanki, S. K.; Barthol, P.; Danilovic, S.; Feller, A.;
   Gandorfer, A.; Hirzberger, J.; Riethmüller, T. L.; Schüssler, M.;
   Bonet, J. A.; Martínez Pillet, V.; del Toro Iniesta, J. C.; Domingo,
   V.; Palacios, J.; Knölker, M.; Bello González, N.; Berkefeld, T.;
   Franz, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.127S
Altcode: 2010arXiv1008.3460S
  The SUNRISE balloon-borne solar observatory consists of a 1 m aperture
  Gregory telescope, a UV filter imager, an imaging vector polarimeter,
  an image stabilization system, and further infrastructure. The first
  science flight of SUNRISE yielded high-quality data that revealed the
  structure, dynamics, and evolution of solar convection, oscillations,
  and magnetic fields at a resolution of around 100 km in the quiet
  Sun. After a brief description of instruments and data, the first
  qualitative results are presented. In contrast to earlier observations,
  we clearly see granulation at 214 nm. Images in Ca II H display narrow,
  short-lived dark intergranular lanes between the bright edges of
  granules. The very small-scale, mixed-polarity internetwork fields
  are found to be highly dynamic. A significant increase in detectable
  magnetic flux is found after phase-diversity-related reconstruction
  of polarization maps, indicating that the polarities are mixed right
  down to the spatial resolution limit and probably beyond.

Title: Supersonic Magnetic Upflows in Granular Cells Observed with
    SUNRISE/IMAX
Authors: Borrero, J. M.; Martínez-Pillet, V.; Schlichenmaier, R.;
   Solanki, S. K.; Bonet, J. A.; del Toro Iniesta, J. C.; Schmidt, W.;
   Barthol, P.; Gandorfer, A.; Domingo, V.; Knölker, M.
Bibcode: 2010ApJ...723L.144B
Altcode: 2010arXiv1009.1227B
  Using the IMaX instrument on board the SUNRISE stratospheric balloon
  telescope, we have detected extremely shifted polarization signals
  around the Fe I 5250.217 Å spectral line within granules in the solar
  photosphere. We interpret the velocities associated with these events
  as corresponding to supersonic and magnetic upflows. In addition, they
  are also related to the appearance of opposite polarities and highly
  inclined magnetic fields. This suggests that they are produced by the
  reconnection of emerging magnetic loops through granular upflows. The
  events occupy an average area of 0.046 arcsec<SUP>2</SUP> and last for
  about 80 s, with larger events having longer lifetimes. These supersonic
  events occur at a rate of 1.3 × 10<SUP>-5</SUP> occurrences per second
  per arcsec<SUP>2</SUP>.

Title: Where the Granular Flows Bend
Authors: Khomenko, E.; Martínez Pillet, V.; Solanki, S. K.; del Toro
   Iniesta, J. C.; Gandorfer, A.; Bonet, J. A.; Domingo, V.; Schmidt,
   W.; Barthol, P.; Knölker, M.
Bibcode: 2010ApJ...723L.159K
Altcode: 2010arXiv1008.0517K
  Based on IMaX/SUNRISE data, we report on a previously undetected
  phenomenon in solar granulation. We show that in a very narrow region
  separating granules and intergranular lanes, the spectral line width
  of the Fe I 5250.2 Å line becomes extremely small. We offer an
  explanation of this observation with the help of magneto-convection
  simulations. These regions with extremely small line widths correspond
  to the places where the granular flows bend from upflow in granules
  to downflow in intergranular lanes. We show that the resolution and
  image stability achieved by IMaX/SUNRISE are important requisites to
  detect this interesting phenomenon.

Title: Bright Points in the Quiet Sun as Observed in the Visible
    and Near-UV by the Balloon-borne Observatory SUNRISE
Authors: Riethmüller, T. L.; Solanki, S. K.; Martínez Pillet, V.;
   Hirzberger, J.; Feller, A.; Bonet, J. A.; Bello González, N.; Franz,
   M.; Schüssler, M.; Barthol, P.; Berkefeld, T.; del Toro Iniesta,
   J. C.; Domingo, V.; Gandorfer, A.; Knölker, M.; Schmidt, W.
Bibcode: 2010ApJ...723L.169R
Altcode: 2010arXiv1009.1693R
  Bright points (BPs) are manifestations of small magnetic elements
  in the solar photosphere. Their brightness contrast not only gives
  insight into the thermal state of the photosphere (and chromosphere) in
  magnetic elements, but also plays an important role in modulating the
  solar total and spectral irradiance. Here, we report on simultaneous
  high-resolution imaging and spectropolarimetric observations of
  BPs using SUNRISE balloon-borne observatory data of the quiet Sun
  at the disk center. BP contrasts have been measured between 214 nm
  and 525 nm, including the first measurements at wavelengths below
  388 nm. The histograms of the BP peak brightness show a clear trend
  toward broader contrast distributions and higher mean contrasts at
  shorter wavelengths. At 214 nm, we observe a peak brightness of up to
  five times the mean quiet-Sun value, the highest BP contrast so far
  observed. All BPs are associated with a magnetic signal, although in
  a number of cases it is surprisingly weak. Most of the BPs show only
  weak downflows, the mean value being 240 m s<SUP>-1</SUP>, but some
  display strong down- or upflows reaching a few km s<SUP>-1</SUP>.

Title: Transverse Component of the Magnetic Field in the Solar
    Photosphere Observed by SUNRISE
Authors: Danilovic, S.; Beeck, B.; Pietarila, A.; Schüssler, M.;
   Solanki, S. K.; Martínez Pillet, V.; Bonet, J. A.; del Toro Iniesta,
   J. C.; Domingo, V.; Barthol, P.; Berkefeld, T.; Gandorfer, A.;
   Knölker, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.149D
Altcode: 2010arXiv1008.1535D
  We present the first observations of the transverse component of
  a photospheric magnetic field acquired by the imaging magnetograph
  SUNRISE/IMaX. Using an automated detection method, we obtain statistical
  properties of 4536 features with significant linear polarization
  signal. We obtain a rate of occurrence of 7 × 10<SUP>-4</SUP>
  s<SUP>-1</SUP> arcsec<SUP>-2</SUP>, which is 1-2 orders of magnitude
  larger than the values reported by previous studies. We show that
  these features have no characteristic size or lifetime. They appear
  preferentially at granule boundaries with most of them being caught
  in downflow lanes at some point. Only a small percentage are entirely
  and constantly embedded in upflows (16%) or downflows (8%).

Title: Detection of Large Acoustic Energy Flux in the Solar Atmosphere
Authors: Bello González, N.; Franz, M.; Martínez Pillet, V.; Bonet,
   J. A.; Solanki, S. K.; del Toro Iniesta, J. C.; Schmidt, W.; Gandorfer,
   A.; Domingo, V.; Barthol, P.; Berkefeld, T.; Knölker, M.
Bibcode: 2010ApJ...723L.134B
Altcode: 2010arXiv1009.4795B
  We study the energy flux carried by acoustic waves excited by convective
  motions at sub-photospheric levels. The analysis of high-resolution
  spectropolarimetric data taken with IMaX/SUNRISE provides a total
  energy flux of ~6400-7700 W m<SUP>-2</SUP> at a height of ~250 km
  in the 5.2-10 mHz range, i.e., at least twice the largest energy
  flux found in previous works. Our estimate lies within a factor of
  two of the energy flux needed to balance radiative losses from the
  chromosphere according to the estimates of Anderson &amp; Athay and
  revives interest in acoustic waves for transporting energy to the
  chromosphere. The acoustic flux is mainly found in the intergranular
  lanes but also in small rapidly evolving granules and at the bright
  borders, forming dark dots and lanes of splitting granules.

Title: Magnetic Loops in the Quiet Sun
Authors: Wiegelmann, T.; Solanki, S. K.; Borrero, J. M.; Martínez
   Pillet, V.; del Toro Iniesta, J. C.; Domingo, V.; Bonet, J. A.;
   Barthol, P.; Gandorfer, A.; Knölker, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.185W
Altcode: 2010arXiv1009.4715W
  We investigate the fine structure of magnetic fields in the atmosphere
  of the quiet Sun. We use photospheric magnetic field measurements from
  SUNRISE/IMaX with unprecedented spatial resolution to extrapolate
  the photospheric magnetic field into higher layers of the solar
  atmosphere with the help of potential and force-free extrapolation
  techniques. We find that most magnetic loops that reach into the
  chromosphere or higher have one footpoint in relatively strong magnetic
  field regions in the photosphere. Ninety-one percent of the magnetic
  energy in the mid-chromosphere (at a height of 1 Mm) is in field
  lines, whose stronger footpoint has a strength of more than 300 G,
  i.e., above the equipartition field strength with convection. The
  loops reaching into the chromosphere and corona are also found to be
  asymmetric in the sense that the weaker footpoint has a strength B &lt;
  300 G and is located in the internetwork (IN). Such loops are expected
  to be strongly dynamic and have short lifetimes, as dictated by the
  properties of the IN fields.

Title: SUNRISE/IMaX Observations of Convectively Driven Vortex Flows
    in the Sun
Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Palacios,
   J.; Martínez Pillet, V.; Solanki, S. K.; del Toro Iniesta, J. C.;
   Domingo, V.; Berkefeld, T.; Schmidt, W.; Gandorfer, A.; Barthol, P.;
   Knölker, M.
Bibcode: 2010ApJ...723L.139B
Altcode: 2010arXiv1009.1992B
  We characterize the observational properties of the convectively driven
  vortex flows recently discovered on the quiet Sun, using magnetograms,
  Dopplergrams, and images obtained with the 1 m balloon-borne SUNRISE
  telescope. By visual inspection of time series, we find some 3.1
  × 10<SUP>-3</SUP> vortices Mm<SUP>-2</SUP> minute<SUP>-1</SUP>,
  which is a factor of ~1.7 larger than previous estimates. The mean
  duration of the individual events turns out to be 7.9 minutes, with
  a standard deviation of 3.2 minutes. In addition, we find several
  events appearing at the same locations along the duration of the time
  series (31.6 minutes). Such recurrent vortices show up in the proper
  motion flow field map averaged over the time series. The typical
  vertical vorticities are lsim6 × 10<SUP>-3</SUP> s<SUP>-1</SUP>,
  which corresponds to a period of rotation of some 35 minutes. The
  vortices show a preferred counterclockwise sense of rotation, which
  we conjecture may have to do with the preferred vorticity impinged by
  the solar differential rotation.

Title: Retrieval of solar magnetic fields from high-spatial resolution
filtergraph data: the Imaging Magnetograph eXperiment (IMaX)
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Martínez Pillet,
   V.; Bonet, J. A.; Vargas Domínguez, S.; Del Toro Iniesta, J. C.
Bibcode: 2010A&A...522A.101O
Altcode: 2010arXiv1006.5510O
  Context. The design of modern instruments does not only imply thorough
  studies of instrumental effects but also a good understanding of the
  scientific analysis planned for the data. <BR /> Aims: We investigate
  the reliability of Milne-Eddington (ME) inversions of high-resolution
  magnetograph measurements such as those to be obtained with the Imaging
  Magnetograph eXperiment (IMaX) aboard the Sunrise balloon. We also
  provide arguments to choose either Fe I 525.02 or 525.06 nm as the
  most suitable line for IMaX. <BR /> Methods: We reproduce an IMaX
  observation using magnetoconvection simulations of the quiet Sun
  and synthesizing the four Stokes profiles emerging from them. The
  profiles are degraded by spatial and spectral resolution, noise,
  and limited wavelength sampling, just as real IMaX measurements. We
  invert these data and estimate the uncertainties in the retrieved
  physical parameters caused by the ME approximation and the spectral
  sampling. <BR /> Results: It is possible to infer the magnetic field
  strength, inclination, azimuth, and line-of-sight velocity from
  standard IMaX measurements (4 Stokes parameters, 5 wavelength points,
  and a signal-to-noise ratio of 1000) applying ME inversions to any
  of the Fe I lines at 525 nm. We also find that telescope diffraction
  has important effects on the spectra coming from very high resolution
  observations of inhomogeneous atmospheres. Diffration reduces the
  amplitude of the polarization signals and changes the asymmetry of
  the Stokes profiles. <BR /> Conclusions: The two Fe I lines at 525 nm
  meet the scientific requirements of IMaX, but Fe I 525.02 nm is to be
  preferred because it leads to smaller uncertainties in the retrieved
  parameters and offers a better detectability of the weakest (linear)
  polarization signals prevailing in the quiet Sun.

Title: Surface Waves in Solar Granulation Observed with SUNRISE
Authors: Roth, M.; Franz, M.; Bello González, N.; Martínez Pillet,
   V.; Bonet, J. A.; Gandorfer, A.; Barthol, P.; Solanki, S. K.;
   Berkefeld, T.; Schmidt, W.; del Toro Iniesta, J. C.; Domingo, V.;
   Knölker, M.
Bibcode: 2010ApJ...723L.175R
Altcode: 2010arXiv1009.4790R
  Solar oscillations are expected to be excited by turbulent flows in
  the intergranular lanes near the solar surface. Time series recorded
  by the IMaX instrument on board the SUNRISE observatory reveal solar
  oscillations at high spatial resolution, which allow the study of
  the properties of oscillations with short wavelengths. We analyze
  two time series with synchronous recordings of Doppler velocity and
  continuum intensity images with durations of 32 minutes and 23 minutes,
  respectively, recorded close to the disk center of the Sun to study
  the propagation and excitation of solar acoustic oscillations. In
  the Doppler velocity data, both the standing acoustic waves and the
  short-lived, high-degree running waves are visible. The standing
  waves are visible as temporary enhancements of the amplitudes of the
  large-scale velocity field due to the stochastic superposition of
  the acoustic waves. We focus on the high-degree small-scale waves by
  suitable filtering in the Fourier domain. Investigating the propagation
  and excitation of f- and p <SUB>1</SUB>-modes with wavenumbers k&gt;1.4
  Mm<SUP>-1</SUP>, we also find that exploding granules contribute to
  the excitation of solar p-modes in addition to the contribution of
  intergranular lanes.

Title: Fully Resolved Quiet-Sun Magnetic flux Tube Observed with
    the SUNRISE/IMAX Instrument
Authors: Lagg, A.; Solanki, S. K.; Riethmüller, T. L.; Martínez
   Pillet, V.; Schüssler, M.; Hirzberger, J.; Feller, A.; Borrero,
   J. M.; Schmidt, W.; del Toro Iniesta, J. C.; Bonet, J. A.; Barthol, P.;
   Berkefeld, T.; Domingo, V.; Gandorfer, A.; Knölker, M.; Title, A. M.
Bibcode: 2010ApJ...723L.164L
Altcode: 2010arXiv1009.0996L
  Until today, the small size of magnetic elements in quiet-Sun areas has
  required the application of indirect methods, such as the line-ratio
  technique or multi-component inversions, to infer their physical
  properties. A consistent match to the observed Stokes profiles could
  only be obtained by introducing a magnetic filling factor that specifies
  the fraction of the observed pixel filled with magnetic field. Here,
  we investigate the properties of a small magnetic patch in the quiet
  Sun observed with the IMaX magnetograph on board the balloon-borne
  telescope SUNRISE with unprecedented spatial resolution and low
  instrumental stray light. We apply an inversion technique based on
  the numerical solution of the radiative transfer equation to retrieve
  the temperature stratification and the field strength in the magnetic
  patch. The observations can be well reproduced with a one-component,
  fully magnetized atmosphere with a field strength exceeding 1 kG and
  a significantly enhanced temperature in the mid to upper photosphere
  with respect to its surroundings, consistent with semi-empirical flux
  tube models for plage regions. We therefore conclude that, within the
  framework of a simple atmospheric model, the IMaX measurements resolve
  the observed quiet-Sun flux tube.

Title: Quiet-sun Intensity Contrasts in the Near-ultraviolet as
    Measured from SUNRISE
Authors: Hirzberger, J.; Feller, A.; Riethmüller, T. L.; Schüssler,
   M.; Borrero, J. M.; Afram, N.; Unruh, Y. C.; Berdyugina, S. V.;
   Gandorfer, A.; Solanki, S. K.; Barthol, P.; Bonet, J. A.; Martínez
   Pillet, V.; Berkefeld, T.; Knölker, M.; Schmidt, W.; Title, A. M.
Bibcode: 2010ApJ...723L.154H
Altcode:
  We present high-resolution images of the Sun in the near-ultraviolet
  spectral range between 214 nm and 397 nm as obtained from the first
  science flight of the 1 m SUNRISE balloon-borne solar telescope. The
  quiet-Sun rms intensity contrasts found in this wavelength range are
  among the highest values ever obtained for quiet-Sun solar surface
  structures—up to 32.8% at a wavelength of 214 nm. We compare the
  rms contrasts obtained from the observational data with theoretical
  intensity contrasts obtained from numerical magnetohydrodynamic
  simulations. For 388 nm and 312 nm the observations agree well with
  the numerical simulations whereas at shorter wavelengths discrepancies
  between observed and simulated contrasts remain.

Title: Quiet-Sun intensity contrasts in the near ultraviolet
Authors: Hirzberger, Johann; Feller, Alex; Riethmüller, Tino L.;
   Schüssler, Manfred; Borrero, Juan M.; Afram, Nadine; Unruh, Yvonne C.;
   Berdyugina, Svetlana V.; Gandorfer, Achim; Solanki, Sami K.; Barthol,
   Peter; Bonet, Jose A.; Martínez Pillet, Valentin; Berkefeld, Thomas;
   Knölker, Michael; Schmidt, Wolfgang; Title, Alan M.
Bibcode: 2010arXiv1009.1050H
Altcode:
  We present high-resolution images of the Sun in the near ultraviolet
  spectral range between 214 nm and 397 nm as obtained from the first
  science flight of the 1-m Sunrise balloon-borne solar telescope. The
  quiet-Sun rms intensity contrasts found in this wavelength range
  are among the highest values ever obtained for quiet-Sun solar
  surface structures - up to 32.8% at a wavelength of 214 nm. We
  compare with theoretical intensity contrasts obtained from numerical
  magneto-hydrodynamic simulations. For 388 nm and 312 nm the observations
  agree well with the numerical simulations whereas at shorter wavelengths
  discrepancies between observed and simulated contrasts remain.

Title: Characterization of horizontal flows around solar pores from
    high-resolution time series of images
Authors: Vargas Domínguez, S.; de Vicente, A.; Bonet, J. A.; Martínez
   Pillet, V.
Bibcode: 2010A&A...516A..91V
Altcode: 2010arXiv1003.2134V
  Context. Though there is increasing evidence linking the moat flow and
  the Evershed flow along the penumbral filaments, there is not a clear
  consensus regarding the existence of a moat flow around umbral cores
  and pores, and the debate is still open. Solar pores appear to be a
  suitable scenario to test the moat-penumbra relation as they correspond
  to a direct interaction between the umbra and the convective plasma
  in the surrounding photosphere without any intermediate structure in
  between. <BR /> Aims: We study solar pores based on high-resolution
  ground-based and satellite observations. <BR /> Methods: Local
  correlation tracking techniques were applied to different-duration
  time series to analyze the horizontal flows around several solar
  pores. <BR /> Results: Our results establish that the flows calculated
  from different solar pore observations are coherent among each other
  and show the determining and overall influence of exploding events in
  the granulation around the pores. We do not find any sign of moat-like
  flows surrounding solar pores, but a clearly defined region of inflows
  surrounding them. <BR /> Conclusions: The connection between moat
  flows and flows associated to penumbral filaments is hereby reinforced.

Title: Magnetic Bright Points in the Quiet Sun
Authors: Sánchez Almeida, J.; Bonet, J. A.; Viticchié, B.; Del
   Moro, D.
Bibcode: 2010ApJ...715L..26S
Altcode: 2010arXiv1004.1885S
  We present a visual determination of the number of bright points
  (BPs) existing in the quiet Sun, which are structures though to trace
  intense kG magnetic concentrations. The measurement is based on a
  0farcs1 angular resolution G-band movie obtained with the Swedish Solar
  Telescope at the solar disk center. We find 0.97 BPs Mm<SUP>-2</SUP>,
  which is a factor 3 larger than any previous estimate. It corresponds to
  1.2 BPs per solar granule. Depending on the details of the segmentation,
  the BPs cover between 0.9% and 2.2% of the solar surface. Assuming their
  field strength to be 1.5 kG, the detected BPs contribute to the solar
  magnetic flux with an unsigned flux density between 13 G and 33 G. If
  network and inter-network regions are counted separately, they contain
  2.2 BPs Mm<SUP>-2</SUP> and 0.85 BPs Mm<SUP>-2</SUP>, respectively.

Title: Magnetic bright points in the quiet Sun
Authors: Sánchez Almeida, J.; Bonet, J. A.; Viticchie, B.; Del
   Moro, D.
Bibcode: 2010iac..talk...95S
Altcode: 2010iac..talk..157S
  No abstract at ADS

Title: Convectively Driven Vortex Flows in the Sun
Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Cabello,
   I.; Domingo, V.
Bibcode: 2008ApJ...687L.131B
Altcode: 2008arXiv0809.3885B
  We have discovered small whirlpools in the Sun, with a size similar to
  terrestrial hurricanes (lesssim0.5 Mm). The theory of solar convection
  predicts them, but they had remained elusive so far. The vortex flows
  are created at the downdrafts where the plasma returns to the solar
  interior after cooling down, and we detect them because some magnetic
  bright points (BPs) follow a logarithmic spiral on their way to being
  engulfed by a downdraft. Our disk-center observations show 0.9 ×
  10<SUP>-2</SUP> vortexes per Mm<SUP>2</SUP>, with a lifetime of the
  order of 5 minutes, and with no preferred sense of rotation. They are
  not evenly spread out over the surface, but they seem to trace the
  supergranulation and the mesogranulation. These observed properties are
  strongly biased by our type of measurement, unable to detect vortexes
  except when they are engulfing magnetic BPs.

Title: Convectively driven vortex flows in the Sun
Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.; Cabello,
   I.; Domingo, V.
Bibcode: 2008iac..talk..143B
Altcode: 2008iac..talk...26B
  No abstract at ADS

Title: Moat Flow in the Vicinity of Sunspots for Various Penumbral
    Configurations
Authors: Vargas Domínguez, S.; Rouppe van der Voort, L.; Bonet,
   J. A.; Martínez Pillet, V.; Van Noort, M.; Katsukawa, Y.
Bibcode: 2008ApJ...679..900V
Altcode: 2008arXiv0802.1457V
  High-resolution time series of sunspots have been obtained with
  the Swedish 1 m Solar Telescope between 2003 and 2006 at different
  locations on the solar disk. Proper motions in seven different active
  regions have been studied. The analysis was performed by applying local
  correlation tracking to every series of sunspots, each of them more than
  40 minutes long. The sunspots' shapes include a different variety of
  penumbral configurations. We report on the systematic behavior of the
  large-scale outflows surrounding the sunspots, commonly known as moat
  flows, that are essentially present only when preceded by a penumbra
  not tangential but perpendicular to the sunspot border. We present
  one case for which this rule appears not to be confirmed. We speculate
  that the magnetic neutral line, which is located in the vicinity of the
  anomalous region, might be responsible for blocking the outflow. These
  new results confirm the systematic and strong relation between the
  moat flows and the existence of penumbrae. A comparative statistical
  study between moats and standard granulation is also performed.

Title: Small magnetic structures in the photosphere, radiative
    properties
Authors: Palacios, Judith; Domingo, Vicente; Cabello, Iballa; Bonet,
   José Antonio; Sánchez Almeida, Jorge
Bibcode: 2008cosp...37.2331P
Altcode: 2008cosp.meet.2331P
  The three dimensional structure of small magnetic field features in the
  photosphere, their dynamic behavior and their radiative properties are
  studied. We analyze data obtained in simultaneous observations made on
  Sept 29 and 30, 2007 with the HINODE spacecraft and the Swedish Solar
  Telescope (SST) in La Palma in different wavelengths, such as CaII
  (396.85 nm) and CN (388.35 nm) and other with Hinode data; and Gband
  (430.56 nm) with SST. Tha analysis is completed with high resolution
  Gband and Gcontinuum (436.39 nm) images from SST obtained on 2005 and
  2006. Magnetograms have been obtained from both observatories. SST
  images have been processed with MOMFB code. Ribbon-like structures and
  "flowers" are studied in detail. Comparisons with solar atmospheric
  models are presented.

Title: Relationships between magnetic foot points and G-band bright
    structures
Authors: Ishikawa, R.; Tsuneta, S.; Kitakoshi, Y.; Katsukawa, Y.;
   Bonet, J. A.; Vargas Domínguez, S.; Rouppe van der Voort, L. H. M.;
   Sakamoto, Y.; Ebisuzaki, T.
Bibcode: 2007A&A...472..911I
Altcode: 2008arXiv0802.1765I
  Aims:Magnetic elements are thought to be described by flux tube models,
  and are well reproduced by MHD simulations. However, these simulations
  are only partially constrained by observations. We observationally
  investigate the relationship between G-band bright points and magnetic
  structures to clarify conditions, which make magnetic structures
  bright in G-band. <BR />Methods: The G-band filtergrams together with
  magnetograms and dopplergrams were taken for a plage region covered
  by abnormal granules as well as ubiquitous G-band bright points,
  using the Swedish 1-m Solar Telescope (SST) under very good seeing
  conditions. <BR />Results: High magnetic flux density regions are
  not necessarily associated with G-band bright points. We refer to the
  observed extended areas with high magnetic flux density as magnetic
  islands to separate them from magnetic elements. We discover that G-band
  bright points tend to be located near the boundary of such magnetic
  islands. The concentration of G-band bright points decreases with inward
  distance from the boundary of the magnetic islands. Moreover, G-band
  bright points are preferentially located where magnetic flux density is
  higher, given the same distance from the boundary. There are some bright
  points located far inside the magnetic islands. Such bright points have
  higher minimum magnetic flux density at the larger inward distance from
  the boundary. Convective velocity is apparently reduced for such high
  magnetic flux density regions regardless of whether they are populated
  by G-band bright points or not. The magnetic islands are surrounded by
  downflows. <BR />Conclusions: These results suggest that high magnetic
  flux density, as well as efficient heat transport from the sides or
  beneath, are required to make magnetic elements bright in G-band.

Title: On the Moat-Penumbra Relation
Authors: Vargas Domínguez, S.; Bonet, J. A.; Martínez Pillet, V.;
   Katsukawa, Y.; Kitakoshi, Y.; Rouppe van der Voort, L.
Bibcode: 2007ApJ...660L.165V
Altcode: 2007astro.ph..2713V
  Proper motions in a sunspot group with a δ-configuration and close to
  the solar disk center have been studied by employing local correlation
  tracking techniques. The analysis is based on a more than 1 hr time
  series of G-band images. Radial outflows with a mean speed of 0.67
  km s<SUP>-1</SUP> have been detected around the spots, the well-known
  sunspots moats. However, these outflows are not found in those umbral
  core sides without penumbra. Moreover, moat flows are only found
  in those sides of penumbrae located in the direction marked by the
  penumbral filaments. Penumbral sides perpendicular to them show no
  moat flow. These results strongly suggest a relation between the
  moat flow and the well-known, filament-aligned Evershed flow. The
  standard picture of a moat flow originating from a blocking of the
  upward propagation of heat is discussed in some detail.

Title: The Evershed Effect Observed with 0.2" Angular Resolution
Authors: Sánchez Almeida, J.; Márquez, I.; Bonet, J. A.; Domínguez
   Cerdeña, I.
Bibcode: 2007ApJ...658.1357S
Altcode: 2006astro.ph.11523S
  We present an analysis of the Evershed effect observed with a resolution
  of 0.2". Using the new Swedish 1 m Solar Telescope and its Littrow
  spectrograph, we scan a significant part of a sunspot penumbra. Spectra
  of the nonmagnetic line Fe I λ7090.4 allows us to measure Doppler
  shifts without magnetic contamination. The observed line profiles are
  asymmetric. The Doppler shift depends on the part of the line used for
  measuring, indicating that the velocity structure of penumbrae remains
  unresolved, even with our angular resolution. The observed line profiles
  are properly reproduced if two components with velocities between zero
  and several km s<SUP>-1</SUP> coexist in the resolution elements. Using
  Doppler shifts at fixed line depths, we find a local correlation
  between upflows and bright structures and between downflows and dark
  structures. This association is not specific to the outer penumbra,
  but it also occurs in the inner penumbra. The existence of such a
  correlation was originally reported in 1969 by Beckers and Schröter,
  and it is suggestive of energy transport by convection in penumbrae.

Title: Evidence Of An Association Between The Presence Of Penumbrae
    And Strong Radial Outflows In Sunspots
Authors: Santiago, Vargas Domínguez; Bonet, J. A.; Martinez Pillet,
   V.; Katsukawa, Y.
Bibcode: 2007ESASP.641E..87S
Altcode:
  Time series of high-resolution images of the complex ac-tive region NOAA
  10786 are studied. The observations were performed in G-band (430.5 nm)
  and in the nearby continuum (463.3 nm), on July 9, 2005 at the Swedish
  1-meter Solar Telecope (SST) in La Palma. Granular proper motions in the
  surroundings of the sunspots have been quantified. A large-scale radial
  outflow in the velocity range 0.3 - 1 km s-1 has been measured around
  the sunspots by using local correlation tracking techniques. However,
  this outflow is not found in those regions around the sunspots with
  no penumbral structure. This result evidences an association between
  penumbrae and the existence of strong horizontal outflows (the moat)
  in sunspots.

Title: S im ulation And Analysis Of VIM Measurements: Feedback On
    Design Parameters
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; Vargas, S.; Bonet,
   J. A.; Martíez Pillet, V.; del Toro Iniesta, J. C.
Bibcode: 2007ESASP.641E..49O
Altcode: 2006astro.ph.11443O
  The Visible-light Imager and Magnetograph (VIM) proposed for the
  ESA Solar Orbiter mission will observe a photo spheric spectral
  line at high spatial resolution. Here we simulate and interpret VIM
  measurements. Realistic MHD models are used to synthesize "observed"
  Stokes profiles of the photospheric Fe I 617.3 nm line. The profiles are
  degraded by telescope diffraction and detector pixel size to a spatial
  resolution of 162 km on the solar surface. We stufy the influence
  of spectral resolving power, noise, and limited wavelength sampling
  on the vector magnetic fields and line-of-sight velocities derived
  from Milne-Eddington inversions of the simulated measurements. VIM
  will provide reasonably accurate values of the atmospheric parametes
  even with the filter widths of 120 Å and 3 wavelength positions plus
  continuum, as long as the noise level is kept below 10-3 Ic.

Title: Proper Motions in Sunspot Penumbrae: Signs of Convection
Authors: Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.
Bibcode: 2006ASPC..358...80B
Altcode:
  Proper motions in penumbra have been measured using local correlation
  tracking techniques in a high spatial resolution series of images
  (∼0.12 arcsec). Assuming these motions to trace true plasma motions,
  we have detected converging flows that arrange the plasma in long
  narrow filaments mostly placed along dark penumbral filaments. These
  converging flows suggest downflows in the filaments of ∼ 200 m
  s<SUP>-1</SUP>. We interpret the association between downflows and
  dark features as a sign of convection that, once several observational
  biases are considered, could transport enough energy to balance the
  radiative losses of penumbra.

Title: The Evershed Effect with 0.2 arcsec Angular Resolution
Authors: Márquez, I.; Bonet, J. A.; Sánchez Almeida, J.; Domínguez
   Cerdeña, I.
Bibcode: 2006ASPC..358...96M
Altcode:
  We present a preliminary analysis of penumbral spectra observed with
  unprecedented angular resolution (0.2 arcsec) using the new Swedish 1-m
  Solar Telescope. The use of a non-magnetic line allows us to measure
  Doppler shifts without magnetic contamination. <P />The observed
  Doppler shifts depend on the part of the line used for measuring,
  indicating that the velocity structure of penumbrae remains unresolved
  even with our resolution. <P />We find a correlation between upflows
  and bright filaments. This association is not specific of the outer
  penumbra but it also occurs in the inner penumbra. <P />The existence
  of such correlation was originally reported by tet{m1 BS69}, <P />and
  it is suggestive of energy transport by convection in penumbrae.

Title: Evidence of an association between the presence of penumbrae
    and strong radial outflows in sunspots
Authors: Vargas Domínguez, S.; Bonet, J. A.; Martinez Pillet, V.;
   Katsukawa, Y.
Bibcode: 2006astro.ph.11500V
Altcode:
  Time series of high-resolution images of the complex active region NOAA
  10786 are studied. The observations were performed in G-band (430.5 nm)
  and in the nearby continuum (463.3 nm), on July 9, 2005 at the Swedish
  1-meter Solar Telecope (SST) in La Palma. Granular proper motions in the
  surroundings of the sunspots have been quantified. A large-scale radial
  outflow in the velocity range 0.3 - 1 km s^[-1] has been measured around
  the sunspots by using local correlation tracking techniques. However,
  this outflow is not found in those regions around the sunspots with
  no penumbral structure. This result evidences an association between
  penumbrae and the existence of strong horizontal outflows (the moat)
  in sunspots.

Title: Detailed design of the imaging magnetograph experiment (IMaX):
    a visible imager magnetograph for the Sunrise mission
Authors: Álvarez-Herrero, A.; Belenguer, T.; Pastor, C.; González,
   L.; Heredero, R. L.; Ramos, G.; Reina, M.; Sánchez, A.; Villanueva,
   J.; Sabau, L.; Martínez Pillet, V.; Bonet, J. A.; Collados, M.;
   Jochum, L.; Ballesteros, E.; Medina Trujillo, J. L.; Ruiz, Cobo B.;
   González, J. C.; del Toro Iniesta, J. C.; López Jiménez, A. C.;
   Castillo Lorenzo, J.; Herranz, M.; Jerónimo, J. M.; Mellado, P.;
   Morales, R.; Rodríguez, J.; Domingo, V.; Gasent, J. L.; Rodríquez, P.
Bibcode: 2006SPIE.6265E..4CA
Altcode: 2006SPIE.6265E.132A
  In this work, it is described the Imaging Magnetograph eXperiment,
  IMaX, one of the three postfocal instruments of the Sunrise mission. The
  Sunrise project consists on a stratospheric balloon with a 1 m aperture
  telescope, which will fly from the Antarctica within the NASA Long
  Duration Balloon Program. IMaX will provide vector magnetograms
  of the solar surface with a spatial resolution of 70 m. This data
  is relevant for understanding how the magnetic fields emerge in
  the solar surface, how they couple the photospheric base with the
  million degrees of temperature of the solar corona and which are the
  processes that are responsible of the generation of such an immense
  temperatures. To meet this goal IMaX should work as a high sensitivity
  polarimeter, high resolution spectrometer and a near diffraction
  limited imager. Liquid Crystal Variable Retarders will be used as
  polarization modulators taking advantage of the optical retardation
  induced by application of low electric fields and avoiding mechanical
  mechanisms. Therefore, the interest of these devices for aerospace
  applications is envisaged. The spectral resolution required will be
  achieved by using a LiNbO <SUB>3</SUB> Fabry-Perot etalon in double
  pass configuration as spectral filter before the two CCDs detectors. As
  well phase-diversity techniques will be implemented in order to improve
  the image quality. Nowadays, IMaX project is in the detailed design
  phase before fabrication, integration, assembly and verification. This
  paper briefly describes the current status of the instrument and the
  technical solutions developed to fulfil the scientific requirements.

Title: High-Resolution Proper Motions in a Sunspot Penumbra
Authors: Márquez, I.; Sánchez Almeida, J.; Bonet, J. A.
Bibcode: 2006ApJ...638..553M
Altcode: 2005astro.ph.10220M
  Local correlation tracking techniques are used to measure proper
  motions in a series of high angular resolution (~0.1") penumbra
  images. If these motions trace true plasma motions, then we have
  detected converging flows that arrange the plasma in long narrow
  filaments cospatial with dark penumbral filaments. Assuming that these
  flows are stationary, the vertical stratification of the atmosphere
  and the conservation of mass suggest downflows in the filaments on
  the order of 200 m s<SUP>-1</SUP>. The association between downflows
  and dark features may be a sign of convection, as it happens with the
  nonmagnetic granulation. Insufficient spatial resolution may explain
  why the estimated vertical velocities are not fast enough to supply
  the radiative losses of penumbrae.

Title: Time series of high resolution photospheric spectra in a
    quiet region of the Sun.  II. Analysis of the variation of physical
    quantities of granular structures
Authors: Puschmann, K. G.; Ruiz Cobo, B.; Vázquez, M.; Bonet, J. A.;
   Hanslmeier, A.
Bibcode: 2005A&A...441.1157P
Altcode: 2012arXiv1205.1725P
  From the inversion of a time series of high resolution slit spectrograms
  obtained from the quiet sun, the spatial and temporal distribution
  of the thermodynamical quantities and the vertical flow velocity is
  derived as a function of optical depth (logτ) and geometrical height
  (z). Spatial coherence and phase shift analyses between temperature
  and vertical velocity depict the height variation of these physical
  quantities for structures of different size. An average granular
  cell model is presented, showing the granule-intergranular lane
  stratification of temperature, vertical velocity, gas pressure and
  density as a function of logτ and z. Studies of a specific small
  and a specific large granular cell complement these results. A strong
  decay of the temperature fluctuations with increasing height together
  with a less efficient penetration of smaller cells is revealed. The
  T-T coherence at all granular scales is broken already at logτ = -1
  or z ~ 170 km. At the layers beyond, an inversion of the temperature
  contrast at granular scales &gt;1.5 arcsec is revealed, both in logτ
  and z. At deeper layers the temperature sensitivity of the H<SUP>-</SUP>
  opacity leeds to much smaller temperature fluctuations at equal logτ
  than at equal z, in concordance with Stein &amp; Nordlund (1998, ApJ,
  499, 914). Vertical velocities are in phase throughout the photosphere
  and penetrate into the highest layers under study. Velocities at the
  largest granular scales (~ 4´´) are still found even at logτ ~ -2.8
  or z ~ 370 km. Again a less efficient height penetration of smaller
  cells concerning convective velocities is revealed, although still
  at logτ ~ -2 or z ~ 280 km structures &gt;1.4 arcsec are detected. A
  similar size distribution of velocity and temperature structures with
  height provides observational evidence for substantial overshoot into
  the photosphere. At deep photospheric layers, the behaviour of the
  vertical velocities reflected in simulations is for the first time
  qualitatively reproduced by observations: intergranular velocities
  are larger than the granular ones and, both reach extrema, where the
  granular one is shifted towards higher layers.

Title: First Implementation Of Phase Diversity At Themis
Authors: Criscuoli, S.; Moro, D. Del; Bonet, J. A.; Márquez, I.
Bibcode: 2005SoPh..228..177C
Altcode:
  Phase diversity techniques are robust post-processing tools for image
  enhancement and correction of telescopic and atmospheric induced
  aberrations. We present results obtained applying the Partitioned
  Phase-Diverse Speckle (PPDS) technique to images acquired at THEMIS. We
  also present an image quality estimator based on image power spectrum
  content we developed in order to automatically evaluate the results
  of large amount of data.

Title: Phase diversity restoration of sunspot images. II. Dynamics
    around a decaying sunspot
Authors: Bonet, J. A.; Márquez, I.; Muller, R.; Sobotka, M.;
   Roudier, Th.
Bibcode: 2005A&A...430.1089B
Altcode:
  Two time series, taken simultaneously in the G-band and in white-light,
  and corrected for telescope aberrations and turbulence perturbations
  using the method of phase diversity, are employed to study the motions
  of granules and G-band bright points (GBPs) in the moat of an old
  regular sunspot. Local correlation tracking and feature tracking have
  been utilized for this purpose. A large-scale radial outflow with
  a mean velocity of 0.51 km s<SUP>-1</SUP> has been measured in the
  sunspot moat. Centres of diverging horizontal motions, identified
  with families of granules formed by repeatedly splitting granules,
  move away from the sunspot. Most of the GBPs in the moat also move
  outwards through radially orientated ``channels'' (confined between
  the borders of adjacent families) with velocities comparable to those
  of the adjacent granules. However, 6% of the GBPs move faster (&gt;1.4
  km s<SUP>-1</SUP>) than the neighbouring granules. GBPs in the moat
  are not regularly distributed but they are less frequent on its solar
  centre side.

Title: The imaging magnetograph eXperiment for the SUNRISE balloon
    Antarctica project
Authors: Martinez Pillet, Valentin; Bonet, Jose A.; Collados, Manuel
   V.; Jochum, Lieselotte; Mathew, S.; Medina Trujillo, J. L.; Ruiz Cobo,
   B.; del Toro Iniesta, Jose Carlos; Lopez Jimenez, A. C.; Castillo
   Lorenzo, J.; Herranz, M.; Jeronimo, J. M.; Mellado, P.; Morales, R.;
   Rodriguez, J.; Alvarez-Herrero, Alberto; Belenguer, Tomas; Heredero,
   R. L.; Menendez, M.; Ramos, G.; Reina, Manuel; Pastor, C.; Sanchez,
   A.; Villanueva, J.; Domingo, Vicente; Gasent, J. L.; Rodriguez, P.
Bibcode: 2004SPIE.5487.1152M
Altcode:
  The SUNRISE balloon project is a high-resolution mission to study solar
  magnetic fields able to resolve the critical scale of 100 km in the
  solar photosphere, or about one photon mean free path. The Imaging
  Magnetograph eXperiment (IMaX) is one of the three instruments that
  will fly in the balloon and will receive light from the 1m aperture
  telescope of the mission. IMaX should take advantage of the 15 days
  of uninterrupted solar observations and the exceptional resolution
  to help clarifying our understanding of the small-scale magnetic
  concentrations that pervade the solar surface. For this, IMaX should
  act as a diffraction limited imager able to carry out spectroscopic
  analysis with resolutions in the 50.000-100.000 range and capable
  to perform polarization measurements. The solutions adopted by the
  project to achieve all these three demanding goals are explained in this
  article. They include the use of Liquid Crystal Variable Retarders for
  the polarization modulation, one LiNbO<SUB>3</SUB> etalon in double pass
  and two modern CCD detectors that allow for the application of phase
  diversity techniques by slightly changing the focus of one of the CCDs.

Title: Phase diversity restoration of sunspot images. I. Relations
    between penumbral and photospheric features
Authors: Bonet, J. A.; Márquez, I.; Muller, R.; Sobotka, M.;
   Tritschler, A.
Bibcode: 2004A&A...423..737B
Altcode: 2004astro.ph..5542B
  We investigate the dynamics of and the relations between small-scale
  penumbral and photospheric features near the outer penumbral
  boundary: penumbral grains (PGs), dark penumbral fibrils, granules,
  and photospheric G-band bright points. The analysis is based on a 2 h
  time sequence of a sunspot close to disc center, taken simultaneously
  in the G-band and in the blue continuum at 450.7 nm. Observations
  were performed at the Swedish Vacuum Solar Telescope (La Palma)
  in July 1999. A total of 2564 images (46 arcsec × 75 arcsec) were
  corrected for telescope aberrations and turbulence perturbations by
  applying the inversion method of phase diversity. Our findings can by
  summarized as follows: (a) one third of the outward-moving PGs pass
  through the outer penumbral boundary and then either continue moving
  as small bright features or expand and develop into granules. (b)
  Former PGs and G-band bright points next to the spot reveal a different
  nature. The latter have not been identified as a continuation of PGs
  escaping from the penumbra. The G-band bright points are mostly born
  close to dark penumbral fibrils where the magnetic field is strong,
  whereas PGs stem from the less-magnetized penumbral component and
  evolve presumably to non-magnetic granules or small bright features.

Title: Bright Points in the Internetwork Quiet Sun
Authors: Sánchez Almeida, J.; Márquez, I.; Bonet, J. A.; Domínguez
   Cerdeña, I.; Muller, R.
Bibcode: 2004ApJ...609L..91S
Altcode: 2004astro.ph..5515S; 2004astro.ph..5515A
  High-resolution G-band images of the interior of a supergranulation
  cell show ubiquitous bright points (BPs; some 0.3 BPs per
  Mm<SUP>2</SUP>). They are located in intergranular lanes and often
  form chains of elongated blobs whose smallest dimension is at
  the resolution limit (135 km on the Sun). Most of them live for a
  few minutes, having peak intensities from 0.8 to 1.8 times the mean
  photospheric intensity. These BPs are probably tracing intense magnetic
  concentrations, whose existence has been inferred in spectropolarimetric
  measurements. Our finding provides a new convenient tool for the study
  of the internetwork magnetism, so far restricted to the interpretation
  of weak polarimetric signals.

Title: Motions of photospheric features in a sunspot moat
Authors: Sobotka, M.; Bonet, J. A.; Márquez, I.; Muller R.;
   Roudier, Th.
Bibcode: 2004HvaOB..28...27S
Altcode:
  Two time series, taken simultaneously in the G-band and the blue
  continuum, corrected for instrumental and atmospheric degradation
  using the method of phase diversity, are employed to study the motions
  of granules and G-band bright points (GBPs) in the moat of an old
  regular sunspot. Centres of diverging horizontal motions, identified
  with families of granules formed by recurrently splitting granules,
  move away from the sunspot. Most of GBPs show radially oriented motions
  in the same direction, with velocities comparable to those of adjacent
  granules. However, 7 % of GBPs move faster (&gt;1.4 km s<SUP>-1</SUP>)
  than the neighbouring granules.

Title: Time series of high resolution photospheric spectra in a quiet
    region of the sun. I. Analysis of global and spatial variations of
    line parameters
Authors: Puschmann, K.; Vázquez, M.; Bonet, J. A.; Ruiz Cobo, B.;
   Hanslmeier, A.
Bibcode: 2003A&A...408..363P
Altcode: 2012arXiv1205.1723P
  A 50 min time series of one-dimensional slit-spectrograms, taken in
  quiet sun at disk centre, observed at the German Vacuum Tower Telescope
  (Observatorio del Teide), was used to study the global and spatial
  variations of different line parameters. In order to determine the
  vertical structure of the photosphere two lines with well separated
  formation heights have been considered. The data have been filtered of
  p-modes to isolate the pure convective phenomenon. From our studies
  of global correlation coefficients and coherence and phase shift
  analyses between the several line parameters, the following results
  can be reported. The convective velocity pattern preserves structures
  larger than 1.0 arcs to the highest layers of the photosphere (
  ~ 435 km). However, at these layers, in the intensity pattern only
  structures larger than 2.0 arcs are still connected with those at the
  continuum level although showing inverted brightness contrast. This
  confirms an inversion of temperature that we have found at a height
  of ~ 140 km. A possible evidence of gravity waves superimposed to
  the convective motions is derived from the phase shift analysis. We
  interprete the behaviour of the full width at half maximum and the
  equivalent width as a function of the distance to the granular borders,
  as a consequence of enhanced turbulence and/or strong velocity gradients
  in the intergranular lanes.

Title: IMax: a visible magnetograph for SUNRISE
Authors: Jochum, Lieselotte; Collados, Manuel; Martínez Pillet,
   Valentin; Bonet, Jose A.; del Toro Iniesta, Jose Carlos; Lopez,
   Antonio; Alvarez-Herrero, Alberto; Reina, Manuel; Fabregat, Juan;
   Domingo, Vicente
Bibcode: 2003SPIE.4843...20J
Altcode:
  The description of the Imaging Magnetograph eXperiment (IMaX) is
  presented in this contribution. This is a magnetograph which will
  fly by the end of 2006 on a stratospheric balloon, together with
  other instruments (to be described elsewhere). Especial emphasis
  is put on the scientific requirements to obtain diffraction-limited
  visible magnetograms, on the optical design and several constraining
  characteristics, such as the wavelength tuning or the crosstalk between
  the Stokes parameters.

Title: Granule and Supergranule properties derived from solar
    timeseries
Authors: Del Moro, D.; Berrilli, F.; Bonet, J. A.; Consolini, G.;
   Kosovichev, A.; Pietropaolo, E.
Bibcode: 2003MmSAI..74..584D
Altcode:
  In this paper we mainly aim at the understanding of temporal evolution
  and spatial characterization of solar granular and supergranular
  features. For this purpose we apply an automatic feature-tracking
  algorithm to three different solar granulation timeseries and to a
  supergranular timeseries of near-surface divergence fields. The single
  lifetimes are calculated measuring the time elapsing between the birth
  and death of each target. In addition, we investigate spatial order of
  surface flows studying the g<SUB>2</SUB>(r) function of time-averaged
  supergranular fields.

Title: Phase diversity at THEMIS : first implementation
Authors: Del Moro, D.; Criscuoli, S.; Bonet, J. A.; Márquez, I.;
   Lemen, C.; Briand, C.
Bibcode: 2003MmSAI..74..811D
Altcode:
  Phase diversity techniques actually provide robust post-processing
  methods to restore solar images degraded by seeing-optical
  aberrations. We present preliminary results of the application of a
  Partitioned Phase-Diverse Speckle (PPDS) technique at THEMIS. The images
  have been acquired using the IPM broad-band CCD camera and reduced
  using a suitable IDL code. The spectral analysis of unrestored/restored
  images shows a significant improvement of image quality, achieving
  diffraction limited resolution.

Title: Infrared photometry of a sunspot near the disk center
Authors: Stangl, S.; Sobotka, M.; Bonet, J. A.; Vázquez, M.;
   Hanslmeier, A.
Bibcode: 2003AN....324..376S
Altcode:
  A time series of broadband images of a sunspot near the disk center
  was obtained simultaneously in two wavelength bands at 0.56 mu m and
  1.55 mu m at the German VTT on June 17, 1998. We computed intensity
  difference images of the best frame pairs which reveal information
  about the facular distribution in the present field of view. Faculae
  are found around pores, in the quiet granulation and as well around
  the sunspot penumbra.

Title: Phase diversity at THEMIS : first implementation
Authors: Del Moro, D.; Lemen, C.; Bonet, J. A.; Márquez, I.;
   Criscuoli, S.; Briand, C.
Bibcode: 2003AN....324..299D
Altcode:
  No abstract at ADS

Title: Models of a mean granular cell
Authors: Puschmann, K.; Ruiz Cobo, B.; Vázquez, M.; Bonet, J. A.;
   Hanslmeier, A.
Bibcode: 2003AN....324..352P
Altcode:
  From inversion of a time series of slit spectra, observed in a quiet
  region of the solar photosphere, averaged models of a granular cell
  have been obtained showing the stratification of physical quantities
  versus optical depth and geometrical height. Furthermore a semi-empiric
  dynamic model of a mean granular cell has been derived and the results
  are presented.

Title: Centre-to-limb variation of solar granulation in the infrared
Authors: Sánchez Cuberes, M.; Vázquez, M.; Bonet, J. A.; Sobotka, M.
Bibcode: 2003A&A...397.1075S
Altcode:
  Broad-band images have been obtained at the extremes of the continuum
  absorption coefficient of the solar atmosphere, at lambda 0.8 mu m
  and lambda 1.55 mu m. Quiet regions have been observed for different
  heliocentric angles. The centre-to-limb variation of granulation
  contrast has been computed in both wavelength ranges and a steeper
  decrease in the contrast is obtained for lambda 0.8 mu m than for
  lambda 1.55 mu m. For positions near the solar limb the granulation
  contrast shows a tendency to increase at both wavelengths. Mean
  granular sizes vary from 1.25 arcsec<SUP>2</SUP> at the disc centre
  to 2 arcsec<SUP>2</SUP> at mu =0.6 in the lambda 0.8 mu m images and
  from 1.24 arcsec<SUP>2</SUP> to 1.85 arcsec<SUP>2</SUP> at lambda
  1.55 mu m. Observations close to the limb detect granular structures
  of 0.\arcsec 96 or even smaller at a distance from the limb of d=
  0.\arcsec 32, equal to the diffraction limit of the telescope at
  lambda 8000 Å. Using an Eddington-Barbier approximation this implies a
  penetration of the temperature fluctuations associated with granulation
  up to approximately z ~ 220 km, although the calculation of response
  functions defines a broader interval.

Title: Phase Diversity Reconstruction of Long Time Series Observations
    at the SVST
Authors: Bonet, J. A.; Márquez, I.
Bibcode: 2003ASPC..307..137B
Altcode:
  No abstract at ADS

Title: Infrared photometric results of a sunspot
Authors: Stangl, S.; Hanslmeier, A.; Sobotka, M.; Bonet, J. A.;
   Vázquez, M.
Bibcode: 2002ESASP.506..473S
Altcode: 2002ESPM...10..473S; 2002svco.conf..473S
  We obtained simultaneously recorded time series of broadband
  images of a sunspot close to the disk center at the German Vacuum
  Tower Telescope, Tenerife, in two wavelength bands at 0.56 μm and
  1.55 μm. Maps of brightness difference images T<SUB>b</SUB>(1.55
  μm) and T<SUB>b</SUB>(0.56 μm) were computed for the best image
  pairs. Furthermore, a scatter plot of the brightness temperatures
  was made where five different magnetic and nonmagnetic regions -
  quiet region (QR), faculae, pores, penumbra, and umbra - in the
  field of view can be clearly distinguished. Pores as well as the
  penumbra are surrounded by the facular regions consisting of several
  single facular elements. However, facular regions are also found in
  non-magnetic vicinity.

Title: Properties of horizontal flows inside and outside a solar pore
Authors: Roudier, Th.; Bonet, J. A.; Sobotka, M.
Bibcode: 2002A&A...395..249R
Altcode:
  Horizontal velocities and their temporal variations inside a large pore
  and in the surrounding granulation are studied from a 73 min sequence
  of white light frames, acquired at the Swedish Vacuum Solar Telescope
  (La Palma). The local correlation tracking technique with high spatial
  (0\farcs 31) and temporal (5 min) resolution was applied to binarized
  images, yielding 14 independent velocity maps. A ring of divergence
  centres around the pore was observed in all the maps. Motions directed
  into the pore, deposited by the divergence centres, continue also within
  the pore but with magnitudes smaller by factor of 2-3. A link between
  the variations of large velocity amplitudes around the pore and the
  brightness fluctuations of umbral dots is suggested. A phase delay
  between velocity and intensity changes at the periphery of the pore,
  probably related to the penetration of bright features inwards across
  the pore's border, was observed.

Title: Evolution of small-scale features at the penumbra-photosphere
    border
Authors: Sobotka, M.; Muller, R.; Bonet, J. A.; Márquez, I.
Bibcode: 2002ESASP.505..579S
Altcode: 2002IAUCo.188..579S; 2002solm.conf..579S
  Time series of images of a sunspot, acquired simultaneously
  in blue light and in G-band at the SVST, La Palma, are used to
  study horizontal motions of granules in the vicinity of the spot
  and evolution of penumbral grains (PGs) near the outer penumbral
  border. Local correlation tracking and feature tracking algorithms
  have been utilized for this purpose. Around sunspots and pores we
  can observe numerous centers of diverging local horizontal motions,
  caused mostly by exploding granules. Around developed spots we find an
  organized motion directed out from the penumbra. The divergence centers
  are carried away from the spot by this motion. In the outer penumbra,
  PGs move mostly outwards, toward the surrounding granulation. About 2/3
  of PGs disappear near the penumbra-granulation border. The remaining
  PGs move across the border, they transform either to granules or to
  small bright features, and continue moving away from the sunspot.

Title: Infrared Photometry of Solar Photospheric
    Structures. II. Center-to-Limb Variation of Active Regions
Authors: Sánchez Cuberes, M.; Vázquez, M.; Bonet, J. A.; Sobotka, M.
Bibcode: 2002ApJ...570..886S
Altcode:
  Simultaneous broadband single images and time series of images have
  been obtained at λ0.8 and λ1.55 μm, which are at the extremes of
  the continuum absorption coefficient of the solar atmosphere. Active
  regions have been observed for different heliocentric angles. Weighted
  difference images between the two wavelength bands have been used
  to identify faculae. Center-to-limb variations of facular relative
  intensity distribution, facular size distribution, and facular
  size-intensity relations have been obtained. At the spatial resolution
  of the observations, faculae show no contrast at the disk center
  at λ0.8 μm, while dark faculae are observed at λ1.55 μm. The
  transition from dark to bright faculae occurs between μ=0.6 and
  0.5 in λ1.55 μm images. The maximum of the mean facular relative
  intensity is found at μ=0.3 for both wavelengths. However, the peak
  of the facular relative intensity is greater and appears closer to
  the limb the larger the faculae are. Brightness temperature maps
  have been computed for the best pairs of images, and temperature
  difference images have been derived. The temperature difference
  T<SUB>b</SUB>(1.55μm)-T<SUB>b</SUB>(0.8μm) in pores is larger than
  that in the quiet photosphere at the disk center, but smaller near
  the limb. Faculae show smaller temperature differences than the quiet
  photosphere at the disk center, but the temperature differences near
  the limb are almost equal. Pores are surrounded by ringlike structures
  of low temperature difference at the disk center. Near the limb these
  ringlike structures appear bright in the brightness temperature maps and
  show a temperature difference similar to that of the quiet photosphere.

Title: Fine structure and dynamics in a light bridge inside a
    solar pore
Authors: Hirzberger, J.; Bonet, J. A.; Sobotka, M.; Vázquez, M.;
   Hanslmeier, A.
Bibcode: 2002A&A...383..275H
Altcode:
  A photometric analysis of the sub-structure of a granular light
  bridge in a large solar pore is performed. The data consist of a
  66 min time series of white light images (lambda = 5425 Å,+/- 50
  Å) of an active region NOAA 7886 obtained at the Swedish Vacuum
  Solar Telescope on La Palma, Canary Islands. The light bridge can
  be resolved into an assembly of small grains embedded in a diffuse
  background with an intensity of about 85% of the mean photospheric
  intensity (I<SUB>phot</SUB>). Following the temporal evolution of these
  sub-structures in their irregular motions inside the light bridge,
  proper motions with velocities up to 1.5 km s<SUP>-1</SUP> can be
  detected. Their lifetime distribution shows a maximum at 5 min and a
  second peak at approximately 20 min. The origin and the decay of these
  sub-structures is very similar to those of granules, i.e. fragmentation,
  merging and spontaneous origination from, and dissolution into, the
  background can be observed. Some of them are able to escape from the
  light bridge into the umbra where they cannot be distinguished from
  adjacent umbral dots. Generally, this study presents evidence that
  the observed phenomenon represents convective motions.

Title: High Resolution Observations of a Photospheric Light Bridge
Authors: Hirzberger, J.; Hanslmeier, A.; Bonet, J. A.; Vázquez, M.
Bibcode: 2001ASSL..259..271H
Altcode: 2001dysu.conf..271H
  We analyzed a 66 min time series of spatially highly resolved white
  light images to study the dynamics of photospheric light bridges
  which we assumed to be a restoration of the quiet surface inside
  sunspots. Similar decaying mechanisms were found as for normal
  photospheric dynamics for granulation.

Title: A Photometric and Magnetic Analysis of the Wilson Effect
Authors: Steinegger, M.; Bonet, J. A.; Vázquez, M.; Martinez
   Pillet, V.
Bibcode: 2001ASSL..259..279S
Altcode: 2001dysu.conf..279S
  For two sunspot groups observed in June 1992 we analyze the
  center-to-limb variation and height dependence of various geometrical
  parameters describing the Wilson effect by using continuum observations
  and simultaneously obtained images of the degree of polarization.

Title: Infrared Photometry of Solar Photospheric Structures. I. Active
    Regions at the Center of the Disk
Authors: Sobotka, M.; Vázquez, M.; Sánchez Cuberes, M.; Bonet,
   J. A.; Hanslmeier, A.
Bibcode: 2000ApJ...544.1155S
Altcode:
  Simultaneous time series of broadband images of two active regions
  close to the disk center were acquired at the Swedish Vacuum
  Solar Telescope, La Palma, in the infrared bands at 1.55 and 0.80
  μm, corresponding to the minimum and maximum continuum opacities,
  respectively. Dark faculae are detected in images obtained as weighted
  intensity differences between both wavelength bands. Maps of brightness
  temperatures T<SUB>b</SUB> (1.55 μm) and T<SUB>b</SUB> (0.80 μm)
  were computed for the best pairs of images. In the scatter plots
  T<SUB>b</SUB> (1.55) versus T<SUB>b</SUB> (0.80), the elements of
  quiet regions can be clearly distinguished from those of faculae and
  pores, while the transition between faculae and pores is smooth. The
  temperature difference T<SUB>b</SUB>(1.55)-T<SUB>b</SUB>(0.80) in
  faculae is lower than that in the quiet photosphere but increases with
  decreasing T<SUB>b</SUB> and is higher inside pores. Most of the pores
  are surrounded by ringlike regions of low temperature difference. The
  minimum intensity of pores at both wavelengths decreases with increasing
  diameter. Maps of horizontal motions of dark faculae and pores were
  derived from time series of intensity-difference images, using the
  local correlation tracking technique. Velocities corresponding to
  large-scale separation of polarities, an emergence of magnetic flux,
  twist and contraction related to a pore formation, shear motions,
  and a twist in dark faculae were measured.

Title: Center-to-Limb Variation of Solar Granulation from Partial
    Eclipse Observations
Authors: Sánchez Cuberes, M.; Bonet, J. A.; Vázquez, M.; Wittmann,
   A. D.
Bibcode: 2000ApJ...538..940S
Altcode:
  We have measured the center-to-limb variation (CLV) of parameters
  describing geometric and photometric statistical properties of the
  solar granulation at 6708 Å. This work is based on an excellent
  series of white-light images obtained with the Swedish Vacuum Solar
  Telescope at Roque de los Muchachos Observatory, La Palma, during the
  partial solar eclipse of 1994 May 10. The lunar limb profile, which is
  visible in each frame, was used as a calibration tool for estimating
  the point-spread function of the combined optical system formed by the
  atmosphere and the telescope. Before restoration, noise was removed
  from the images by a novel application of the so-called optimum filter
  for two-dimensional objects. The latter was optimized in terms of
  rms error and was constructed from very precise smoothed models of the
  specific power spectrum of the granulation at each position on the solar
  disk. The determination of the positions on the solar disk was achieved
  with high accuracy by matching the position of the Moon's limb in our
  images to a numerical simulation of the eclipse geometry. The CLV curve
  of the ΔI<SUB>rms</SUB> granular contrast shows one of the steepest
  gradients among those reported in the literature and quite a high value
  (9.6%) at the disk center considering that our working wavelength is
  in the far-red range of the solar spectrum. The elliptical shape of
  the restored power spectra with ellipticities equal to those expected
  just from foreshortening proves that radiative transfer effects do not
  alter the isotropy of the horizontal intensity pattern of the solar
  granulation, at least up to μ=0.4. The mean wavenumber, k, derived
  from the two-dimensional power spectra azimuthally integrated along
  the ellipses amounts to a value of 6.15 Mm<SUP>-1</SUP> at the center
  of the solar disk and then shows a decrease toward the limb. Apart
  from the power spectra analysis, a direct statistical study of the
  granulation size and brightness, based on the image segmentation for
  defining granular contours, has also been performed. A general increase
  in both granular and intergranular areas is found as we move toward the
  solar limb. The mean granular cell area varies from 1.36 Mm<SUP>2</SUP>
  at μ=1 up to 2.06 Mm<SUP>2</SUP> at μ=0.6, and in parallel, the
  granular filling factor (the percentage of area of the image covered
  by granules) decreases from 44.2% to 42.8%. In the small area range,
  the granular brightness increases linearly with the granular cell size
  and is preserved constant, on average, for granular cells larger than
  ~2.0". No slope variation is found for the intergranular intensities
  versus granular cell areas. Observations close to the solar limb detect
  granular structures as small as 0.53" or even smaller up to a distance
  of at least ~0.5" from the limb, showing that the ΔT associated
  with the granulation persist at least until z~200 km. However, this
  penetration could be different for small and large granules because we
  find several hints indicating the progressive disappearance of small
  structures toward the limb.

Title: Infrared Photometry of Solar Active Regions
Authors: Sobotka, M.; Vázquez, M.; Cuberes, M. S.; Bonet, J. A.;
   Hanslmeier, P.
Bibcode: 2000JApA...21..289S
Altcode:
  No abstract at ADS

Title: Long-Term Observations of Solar Active Regions at the VNT
Authors: Bonet, J. A.; Casas, R.; Giammanco, C.; Martinez Pillet,
   V.; Vazquez
Bibcode: 2000ESASP.463..635B
Altcode: 2000sctc.proc..635B
  No abstract at ADS

Title: Time Series of Solar Granulation Images. III. Dynamics of
    Exploding Granules and Related Phenomena
Authors: Hirzberger, J.; Bonet, J. A.; Vázquez, M.; Hanslmeier, A.
Bibcode: 1999ApJ...527..405H
Altcode:
  The evolution of exploding granules is studied by using a spatially as
  well as temporally highly resolved time series of white-light images of
  80 minute duration. The results of this study show that the dynamics
  of exploding granules is strongly affected by their surroundings and
  that their appearance is closely related to the mesogranular flow
  field. Comparing the behavior of exploding granules with that of
  smaller dark structures--so-called dark dots--and with the results of
  model simulations leads to the conclusion that both phenomena, as well
  as a third newly found phenomenon (dark structures occurring in the
  centers of granules that are approximately twice as large as dark dots
  but smaller than typical centers of exploding granules) are different
  types of strong downflows developing in the centers of granules. The
  motions of all these three phenomena--the expansion of exploding
  granules and the proper motions of the smaller dark structures,
  respectively--can reach velocities close to the sound speed in the solar
  photosphere. Another type of structure--narrow intergranular connections
  between granules--has also been studied. Our results show that these
  structures are real solar phenomena and are not caused by a variation
  of the image quality. Therefore, in following and describing their
  evolution, we try to find an explanation for their frequent occurrence.

Title: Interaction of Convective Structures with the Magnetic Field
    of Solar Pores
Authors: Sobotka, M.; Vázquez, M.; Bonet, J. A.; Hanslmeier, A.
Bibcode: 1999ASPC..184...60S
Altcode:
  Time series of high-resolution white-light images of solar pores are
  analyzed. Granular motions in the vicinity of pores are driven by
  mesogranular flows: Motions toward the pore dominate in the 2 arcsec
  zone around the pore boundary, while at larger distances the granules
  move away from the pore. Triggered by these motions, small granules
  and granular fragments located close to the pore border penetrate into
  the pore, where they move inwards as short-lived bright features very
  similar to umbral dots. The formation of a transitory penumbra-like
  structure at the border of a large pore was observed simultaneously
  with a temporary reorganization of adjacent granular field to expanding
  elongated granules separated by dark filaments.

Title: Time Series of Solar Granulation Images. II. Evolution of
    Individual Granules
Authors: Hirzberger, J.; Bonet, J. A.; Vázquez, M.; Hanslmeier, A.
Bibcode: 1999ApJ...515..441H
Altcode:
  The properties of the evolution of solar granulation have been
  studied using an 80 minute time series of high spatial resolution
  white-light images obtained with the Swedish Vacuum Solar Telescope at
  the Observatorio del Roque de los Muchachos, La Palma. An automatic
  tracking algorithm has been developed to follow the evolution of
  individual granules, and a sample of 2643 granules has been analyzed. To
  check the reliability of this automatic procedure, we have manually
  tracked a sample of 481 solar granules and compared the results of both
  procedures. An exponential law gives a good fit to the distribution of
  granular lifetimes, T. Our estimated mean lifetime is about 6 minutes,
  which is at the lower limit of the ample range of values reported
  in the literature. We note a linear increase in the time-averaged
  granular sizes and intensities with the lifetime. T=12 minutes marks
  a sizeable change in the slopes of these linear trends. Regarding
  the location of granules with respect to the meso- and supergranular
  flow field, we find only a small excess of long-lived granules in the
  upflows. Fragmentation, merging, and emergence from (or dissolution
  into) the background are the birth and death mechanisms detected,
  resulting in nine granular families from the combination of these
  six possibilities. A comparative study of these families leads to
  the following conclusions: (1) fragmentation is the most frequent
  birth mechanism, while merging is the most frequent death mechanism;
  (2) spontaneous emergence from the background occurs very rarely,
  but dissolution into the background is much more frequent; and (3)
  different granular mean lifetimes are determined for each of these
  families; the granules that are born and die by fragmentation have
  the longest mean lifetime (9.23 minutes). From a comparison of the
  evolution of granules belonging to the most populated families, two
  critical values appear for the initial area in a granular evolution:
  0.8 Mm<SUP>2</SUP> (d<SUB>g</SUB>=1.39") and 1.3 Mm<SUP>2</SUP>
  (d<SUB>g</SUB>=1.77"). These values mark limits characterizing the birth
  mechanism of a granule, and predict its evolution to some extent. The
  findings of the present work complement the earlier results presented
  in this series of papers and reinforce with new inputs, as far as
  the evolutionary aspects are concerned, the conclusion stated there
  that granules can be classified into two populations with different
  underlying physics. The boundary between these two classes could be
  established at the scale of d<SUB>g</SUB>=1.4".

Title: Implementation of a Filter for the Restoration of Solar
    Granulation Images
Authors: Sánchez Cuberes, M.; Bonet, J.; Vázquez, M.; Wittmann, A.
Bibcode: 1999ASPC..183..515S
Altcode: 1999hrsp.conf..515S
  No abstract at ADS

Title: The Spectrum of Intensity Fluctuations Across Penumbral
    Filaments
Authors: Sánchez Almeida, J.; Bonet, J.
Bibcode: 1999ASPC..183...87S
Altcode: 1999hrsp.conf...87S
  No abstract at ADS

Title: Temporal Evolution of Fine Structures in and around Solar Pores
Authors: Sobotka, Michal; Vázquez, Manuel; Bonet, José Antonio;
   Hanslmeier, Arnold; Hirzberger, Johann
Bibcode: 1999ApJ...511..436S
Altcode:
  Time series of high-resolution white-light images of six solar pores,
  observed in 1993 and 1995 at the Swedish Vacuum Solar Telescope (La
  Palma), are analyzed. The pores constitute an almost ideal laboratory
  in which to study the interaction of a vertical magnetic field with
  surrounding convective motions, without the perturbation of the inclined
  magnetic field in the penumbra. Umbral dots observed in a large (D=8.9")
  pore are similar to those in mature umbrae, but they live longer, are
  brighter, and have a higher filling factor. Granular motions in the
  vicinity of pores are driven by mesogranular flows. Motions toward the
  pore dominate in the 2" zone around the pore boundary, while at larger
  distances the granules move away from the pore. Pushed by these motions,
  small granules and granular fragments located close to the pore border
  sometimes penetrate into the pore, where they move inward as bright
  short-lived features very similar to umbral dots. The capture of bright
  features by the pore is probably a microscale manifestation of the
  ``turbulent erosion,'' which results in the decay of the pore. Formation
  of a transitory penumbra-like structure at the border of the large
  pore was observed simultaneously with the appearance of expanding
  elongated granules, separated by dark filaments, in an adjacent
  granular field. These effects can be interpreted as a consequence of
  emerging bipolar magnetic ``loops'' caused by a temporary protrusion
  of opposite magnetic polarity.

Title: Time Evolution of Solar Granulation
Authors: Hirzberger, J.; Hanslmeier, A.; Bonet, J.; Vázquez, M.
Bibcode: 1999ASPC..183..507H
Altcode: 1999hrsp.conf..507H
  No abstract at ADS

Title: Time Series of Solar Photospheric Spectrograms Bisector
    Analysis
Authors: Hanslmeier, A.; Bonet, J.; Vázquez, M.
Bibcode: 1999ASPC..183..479H
Altcode: 1999hrsp.conf..479H
  No abstract at ADS

Title: Granulation in active regions as compared to quiet regions
Authors: Hirzberger, J.; Bonet, J. A.; Vázquez, M.; Hanslmeier, A.;
   Sobotka, M.
Bibcode: 1999AGAb...15...88H
Altcode: 1999AGM....15..P09H
  A comparative study of the statistical properties of granulation
  in active and quiet regions is performed. The analysis is based on a
  high-resolution time series of simultaneous white light (lambda5425 Å)
  and G-band (lambda 4308 Å) images obtained at the Swedish Vacuum Solar
  Telescope, La Palma, Canary Islands. The G-band images have been used
  to discern quiet and active regions in the field of view, whereas the
  white-light images were taken to analyze the photometry, size and time
  evolution of granules in regions of different magnetic activity. Power
  spectra confirm that the granular size decreases with increasing G-band
  brightness. Granules with diameters below 0''.8 are systematically
  brighter in the abnormal granulation than in quiet regions. These
  small and bright elements are embedded in a diffuse background of
  approximately mean photospheric brightness covering all the fields of
  abnormal granulation. The granular lifetime decreases with increasing
  G-band brighness. The conclusions about the behaviour of the granulation
  have been decontaminated of the influence of magnetic elements (the
  so-called Bright Points), that have been separated using criteria
  of size (d &lt; 0''.5) and lifetime (T &gt; 6 min). A significant
  fraction of them are concentrated in regions of high G-band activity,
  an emerging flux region, and the rest are m ainly aligned outlining a
  cellular pattern (the magnetic network formed by supergranular motions).

Title: High Spatial Resolution Imaging in Solar Physics
Authors: Bonet, J. A.
Bibcode: 1999ASSL..239....1B
Altcode: 1999msa..proc....1B
  Physical processes in the Sun give rise to an ample variety of
  structures on different spatial scales that in many cases are very
  small, with sizes probably below the resolution limit of existing
  solar telescopes (see Sánchez Almeida, 1997; Sánchez Almeida and
  Bonet, 1997). Thus, the interpretation of solar phenomena requires
  the study of these structures, and consequently high spatial
  resolution observations are necessary to understand the physics
  of the Sun. These observations must be complemented by an equally
  important high-resolution spectroscopic analysis, including polarimetric
  measurements to determine the magnetic field strength (magnetic fields
  have a pervasive influence on the physical events in the Sun). However,
  in the present study we shall concentrate on the first aspect of the
  observational process, i.e. we shall describe some of the tools and
  resources available for producing high spatial resolution images.

Title: The Spectrum of Fluctuations across Penumbral Filaments
Authors: Sánchez Almeida, J.; Bonet, J. A.
Bibcode: 1998ApJ...505.1010S
Altcode:
  We estimate the typical spectrum of spatial fluctuations of intensity
  due to the penumbral filaments. High angular resolution continuum
  images are used (cut-off frequencies equivalent to 0.28" wavelength
  of about 5257 Å). The amplitude of the observed spectra follows the
  modulation transfer function of our optical system. In other words,
  the spectrum of real penumbral fluctuations seems to be flat up to the
  higher observable spatial frequency. We expect it to continue far beyond
  the artificial instrumental cutoff, which implies that the structure
  of the penumbra remains unresolved to the present solar observations.

Title: Near-infrared camera for solar research: a photometric
    application
Authors: Reyes, Marcos; Joven-Alvarez, Enrique; Collados, Manuel;
   Bonet, Jose A.; Vazquez, Manuel; Diaz, Jose J.; Fuentes, F. Javier;
   Escalera, Victor G.; Rodriguez, Luis F.; Garcia-Herrero, Jose L.
Bibcode: 1998SPIE.3410..233R
Altcode:
  We report here the main characteristics of a near IR camera devoted to
  astrophysical solar research, which has been developed by the Instituto
  de Astrofisica de Canarias (IAC). The system is now being used for
  photometric and spectroscopic applications, and it will also be used
  for spectropolarimetry in the near future. The first application is
  described below in detail. The IACs IR camera is based on a Rockwell
  256 X 256 HgCdTe NICMOS3 array, sensitive from 1 to 2.5 microns. The
  necessary cooling system is a LN2- cryostat, designed and built by IR
  labs under out requirements. The main electronics are the standard VME-
  based, FPGA programmable MCE-3 system, also developed by IR labs. We
  have implemented different readout schemes to improve sped, reduce
  noise and avoid seeing effects, taking into account each specific
  application. Data are transferred via fiber optics to a control unit,
  which re-send them to the main data acquisition system. Several
  acquisition modes to select the best images have been implemented,
  and a real- time data processing is available, the entire camera has
  been characterized and calibrated, and the main radiometric parameters
  given. Preliminary test in spectroscopic observations have been made
  in the German Towers at the Observatorio del Teide in Tenerife, Spain,
  and a series of photometric measurements performed in the Swedish Solar
  Telescope, at the Observatorio del Roque de los Muchachos in La Palma,
  Spain. As examples, some scientific results are also presented.

Title: Centre-To-Limb Variation of the Solar Granulation
Authors: Sánchez Cuberes, M.; Bonet, J. A.; Vázquez, M.; Wittmann,
   A. D.
Bibcode: 1998Ap&SS.263..343S
Altcode: 1999Ap&SS.263..343S
  An excellent series of images of solar granulation was taken during
  the partial solar eclipse of 1994 May 10 at the Swedish Vacuum Solar
  Telescope at Roque de los Muchachos Observatory. Making use of the
  lunar limb profile, images at different heliocentric positions were
  corrected for instrumental and atmospheric effects. The centre-to-limb
  variation of the granulation contrast was calculated and compared with
  previous determinations.

Title: On the Intensity Thresholds of the Network and Plage Regions
Authors: Steinegger, Michael; Bonet, Jose A.; Vázquez, Manuel;
   Jiménez, Antonio
Bibcode: 1998SoPh..177..279S
Altcode:
  A period of minimum solar activity in April and May 1996 was used to
  analyze full-disk CaK spectroheliograms with the aim of deriving the
  intensity thresholds of the quiet network and the plages by applying
  the so-called inflexion point method. The average network intensity
  threshold is found to be influenced mainly by the seeing, whereas the
  average plage threshold shows an increasing trend from disk center
  towards the solar limb. Both parameters are compared with the results
  of other authors.

Title: On the Intensity Thresholds of the Network and Plage Regions
Authors: Steinegger, Michael; Bonet, Jose A.; Vázquez, Manuel;
   Jiménez, Antonio
Bibcode: 1998sers.conf..279S
Altcode:
  No abstract at ADS

Title: Time Series of Solar Granulation Images. I. Differences
    between Small and Large Granules in Quiet Regions
Authors: Hirzberger, J.; Vázquez, M.; Bonet, J. A.; Hanslmeier, A.;
   Sobotka, M.
Bibcode: 1997ApJ...480..406H
Altcode:
  A 90 minute time series of high spatial resolution white-light images
  of solar granulation, obtained at the Swedish Vacuum Solar Tower
  (Observatorio del Roque de los Muchachos, La Palma), was analyzed
  to study how the physical properties of the granules changed with
  size. The observational material was corrected for global motions and
  for the instrumental profile, and a subsonic filter was applied. A
  definition of granular border was adopted using the inflection points
  of the intensity of the images, and the granular cells were defined
  as areas including, in addition to the granules, one-half of their
  surrounding intergranular lanes. Using time series to investigate the
  average behavior of solar granulation has three strong advantages:
  the first is the possibility of removing the acoustic waves; second,
  the possibility of estimating the effect of the variability of
  seeing on our results; and, third, the opportunity to attain high
  statistical significance in the analysis as a result of the large
  number of extracted granules (61,138). <P />It is shown that the
  granules of the sample can be classified according to their mean
  and maximum intensities and their fractal dimension into two regimes,
  with diameters smaller than and larger than 1.4", respectively. A broad
  transition region in which both regimes coexist was found. The resolved
  internal brightness structure of both the granules and the intergranular
  lanes shows a linear increase of the number of substructures with the
  granular and intergranular areas. The diameters of these substructures
  range between our effective resolution limit (~0.3") and ~1.5",
  with preferential sizes at 0.65" and 0.55", respectively. Moreover,
  it seems that large and small granules are unevenly distributed with
  respect to the large-scale vertical flows. Thus smaller granules are
  more concentrated along downdrafts whereas larger ones preferentially
  occupy the updrafts. Finally, a physical scenario compatible with the
  existence of these two granular populations is discussed.

Title: Simulation of Seeing Influences on the Photometric
    Determination of Sunspot Areas
Authors: Steinegger, Michael; Bonet, José A.; Vázquez, Manuel
Bibcode: 1997SoPh..171..303S
Altcode:
  Various methods for measuring areas of sunspots and umbrae are compared
  to test their robustness against changing seeing conditions. The
  influence of the seeing is simulated by artificially degrading
  high-resolution sunspot images. A new procedure - the so-called
  inflexion point method - for area determinations is described. It
  is based on the calculation of the inflexion point contours of the
  two-dimensional sunspot intensity distribution. The areas derived with
  this method are much more stable against seeing influences than those
  obtained by the other procedures tested. The effect of the seeing on
  the measurements of the bolometric sunspot contrast and irradiance
  deficit produced by a sunspot is also studied.

Title: The IAC's Near Infrared Camera
Authors: Collados, M.; Joven, E.; Fuentes, F. J.; Diaz, J. J.;
   Gonzalez Escalera, V.; Bonet, J. A.; Vazquez, M.
Bibcode: 1997ASPC..118..361C
Altcode: 1997fasp.conf..361C
  Here we report the main characteristics of the recently acquired near
  infrared camera. It is based on a 256x256 HgCdTe Nicmos-3 array,
  sensitive from 1 mu m to 2.5mu m. The pixel size is 40mu mx40mu
  m, adequate for the spatial and spectral scales at the different
  telescopes operating at the observatories of La Palma and Tenerife. The
  cooling system operates with LN2 with a hold time larger than 20
  hours. The camera will be used for photometric, spectroscopic and
  spectropolarimetric observations.

Title: A new method for the photometric determination of umbral and
    total sunspot areas.
Authors: Steinegger, M.; Bonet, J. A.; Vázquez, M.
Bibcode: 1997joso.proc...89S
Altcode:
  No abstract at ADS

Title: Time evolution of solar granulation phenomena.
Authors: Hirzberger, J.; Bonet, J. A.; Hanslmeier, A.; Vázquez, M.;
   Sobotka, M.
Bibcode: 1996AGAb...12..160H
Altcode:
  No abstract at ADS

Title: On the Energy Balance of Solar Active Regions
Authors: Steinegger, Michael; Vazquez, Manuel; Bonet, Jose A.; Brandt,
   Peter N.
Bibcode: 1996ApJ...461..478S
Altcode:
  Ground-based observations of the sunspot irradiance deficit Ψ
  and the excess by facular regions in the period 1989 June 3-15 are
  analyzed using photometric techniques. The results are compared with
  solar irradiance measurements taken by the Nimbus 7 satellite. The
  photographic sunspot data were obtained at the Vakuum Newton
  Teleskop, Observatorio del Teide (Tenerife), and the information on
  facular emission was derived by means of a "proxy" method from the
  analysis of full-disk Ca II K spectroheliograms taken at Sacramento
  Peak Observatory. <P />The first part of the observing period was
  characterized by a rather constant activity with sunspot groups of
  small and medium size, whereas the second part (from June 8 onward)
  exhibited a drastic increase of activity, dominated by the appearance
  of the large group NOAA 5528. <P />By increasing the pixel size of
  the digitized photographic data, the influence of the variable spatial
  resolution on the measurements is simulated. Above a certain threshold,
  the bolometric sunspot contrast falls and the spot area grows; however,
  the resulting influence on the sunspot deficit Ψ and the corresponding
  umbral parameters (area, contrast, and deficit) is negligible. <P
  />Data of areas of sunspot groups (total and umbral) from different
  observatories are compared with our measurements. Total areas show
  similar values, but umbral areas from our measurements are clearly
  larger than those estimated from full-disk images, like those from the
  Debrecen and San Fernando Observatories. <P />Analyzing the data of
  single spots, we confirm earlier findings, namely, that the bolometric
  contrast is lower than 0.32, the standard value used in the calculation
  of the photometric sunspot index, and we report that small spots exhibit
  smaller bolometric contrasts than larger ones. The intensity minimum
  of the spots is a very appropriate parameter to describe their global
  thermal properties; it is linearly proportional to the total (α) and
  umbral (α<SUB>μ</SUB>) bolometric contrasts and also correlates with
  the maximum strength of the magnetic field of the spots and with the
  spot's size. <P />The energy balance of individual active regions seems
  to depend mainly on the area ratio of the plage and the corresponding
  sunspot group. The different rates at which these areas change produces
  the temporal evolution of the energy balance. <P />The daily variations
  of the global activity indices radio flux at 10.7 cm, Mg II core-to-wing
  ratio, and the average magnetic field are well correlated with the
  fluctuations of irradiance and the spot deficit Ψ. But on the other
  hand, the equivalent width of the He I λ10830 line and the coronal
  index do not follow this behavior. <P />The irradiance fluctuations,
  as measured by Nimbus 7, can be modeled to within 60 parts per million
  (ppm) using only our ground-based determination of Ψ and Φ. By adding
  the sunspot deficit Ψ to the irradiance fluctuations, the result
  is modeled to within 25 ppm using an empirical law that combines our
  Φ with a set of global activity indices. <P />After correcting the
  irradiance measurements for the facular Φ and spot Ψ contributions,
  a residual remains with an apparent periodicity of 6 days. Different
  sources to explain this variability are discussed and the importance
  of an adequate determination of the threshold of Ca II K brightness
  for the calculation of Φ is explained.

Title: Two-dimensional, high spatial resolution, solar spectroscopy
    using a correlation tracker. I. Correlation tracker description.
Authors: Ballesteros, E.; Collados, M.; Bonet, J. A.; Lorenzo, F.;
   Viera, T.; Reyes, M.; Rodriguez Hidalgo, I.
Bibcode: 1996A&AS..115..353B
Altcode:
  In this paper the description of the Solar Correlation Tracker prototype
  built by the Instituto de Astrof isica de Canarias is presented. The
  system is mainly conceived as a solar image tranquilizer, although a
  scanning utility has also been included in order to displace the image
  on the final focal plane with sub-arcsecond steps, thus allowing to
  perform two-dimensional high spatial resolution spectroscopy. The
  behaviour of the different elements of the tracker is shown,
  as well as their influence in the performance of the system. The
  restrictions of the Absolute Differences algorithm, used to detect
  image motion when granulation fields are considered, are extensively
  discussed. Laboratory and telescope tests have demonstrated the
  capabilities of the system. The electronic components have been adapted
  to new optics and mechanics developed at the Kiepenheuer Institut to
  build an Advanced Solar Correlation Tracker. The final version of the
  system has been installed at the German VTT of the Spanish Observatorio
  del Teide. The tests carried out have demonstrated that a bandwidth
  of about 60Hz (for an attenuation factor of two) is achieved, which
  is approximately four times larger than that of previous Correlation
  Trackers, at the same level of attenuation.

Title: Numerical modelling of spectral line asymmetries in
    photospheric structures. II. Plage regions.
Authors: Marquez, I.; Bonet, J. A.; Vazquez, M.
Bibcode: 1996A&A...306..305M
Altcode:
  A numerical code has been developed for modelling the asymmetries in
  three spectral lines (K I 7699, Fe I 5576 and Fe I 5635A) formed at
  different photospheric heights and observed in plage regions near the
  solar disk center. The aim of this work was to reproduce the absolute
  line bisectors obtained from low resolution observations. The mere
  insertion of a flux tube in a model of quiet granulation, without
  mutual interaction, has proved insufficient to explain many of
  the observational results. Therefore, several models of abnormal
  granulation close to the tube, representing the influence of the
  magnetic field, are considered. The code consists of two computation
  modules, one representing a model of the unperturbed photosphere,
  and the other including a flux tube inserted in a model of altered
  granulation; various combinations of both computation modules allow
  different values of the magnetic filling factor to be simulated. The
  influence of other physical parameters and observational aspects
  on the bisector is also discussed, e.g. waves, microturbulence,
  defective time or spatial averages, etc. The proposed model reproduces
  the observed variation in the shape and in the absolute shift of the
  bisector when the filling factor increases. Likewise, the computed
  spatial distribution of intensity in the continuum fits many of the
  photometric results reported in the literature for plage regions.

Title: Numerical modelling of spectral line asymmetries in
    photospheric structures. I. Quiet Sun.
Authors: Marquez, I.; Bonet, J. A.; Vazquez, M.; Woehl, H.
Bibcode: 1996A&A...305..316M
Altcode:
  Modelling of asymmetries in spectral lines with different formation
  heights (K I 7699, Fe I 5576 and Fe I 5635A), observed in the quiet Sun
  at the disk center, has been performed with the aim of reproducing the
  absolute line bisectors obtained from low resolution observations. The
  influence of a number of physical and observational factors on the
  bisector shape and line shifts, acting together or separately, is
  discussed, e.g. mesogranular flows, waves, microturbulence, defective
  temporal and spatial averages, etc. The simulations are based on the
  VAL-C model (Vernazza et al. 1981) representing the mean photosphere,
  and the granular model by Nelson (1978). Following evidence in the
  literature, the best match to the observed absolute mean bisectors
  is obtained by including in the numerical code a gravity wave and
  a strengthening of the microturbulence in the lower layers of the
  intergranule.

Title: On the Dynamics of Bright Features in Sunspot Umbrae
Authors: Sobotka, Michal; Bonet, Jose A.; Vazquez, Manuel; Hanslmeier,
   Arnold
Bibcode: 1995ApJ...447L.133S
Altcode:
  Time series of white-light pictures of the sunspot NOAA 7522, obtained
  at the Swedish Vacuum Solar Telescope (La Palma), were analyzed
  to study the proper motion of bright features in sunspots. For the
  first time, its relation with the dark nuclei present in the umbra is
  investigated. The bright features are visible in the penumbra as bright
  grains moving into the umbra. A few of them cross the penumbra/umbra
  boundary, becoming peripheral umbral dots, which move farther into
  the umbra until they meet dark nuclei, braking their motion and
  disappearing. In some cases the encounter with a dark nucleus produces
  a brightening of the central umbral dots placed on the opposite side
  of the nucleus. A similar phenomenon is observed in the grains of a
  faint light bridge, when bright penumbral grains collide with one of
  the edges of the bridge.

Title: Photometry of sunspot pores from partial eclipse observations.
Authors: Bonet, J. A.; Sobotka, M.; Vazquez, M.
Bibcode: 1995A&A...296..241B
Altcode:
  White-light images, centered at λ6708A, were obtained at the Swedish
  Solar Telescope, La Palma, on occasion of the 1994 May 10 partial solar
  eclipse. From the recorded information, 5 frames showing several pores
  together with the moon's limb were selected for detailed photometric
  analysis. The observed intensity profile of the moon's limb projected
  against the solar disk was used to derive, from each frame, the
  Point Spread Function of the atmosphere + instrument to restore the
  images. The characteristics of the obtained PSFs -low noise and precise
  determination of the wings far away from the core- enabled us to avoid
  arbitrary assumptions about analytical approximations. The FWHM of these
  functions was typically 0.47". Several bright features were identified
  in one of the pores. After determining the photometric parameters of
  these fine umbral structures their link with the population of the
  bright features in the umbra of evolved spots is discussed in the
  framework of the dependence of sunspot properties on the spot size.

Title: Area and intensity distribution in solar granulation
Authors: Hirzberger, J.; Hanslmeier, A.; Bonet, J. A.; Vázquez, M.
Bibcode: 1995IAUS..176P.114H
Altcode:
  No abstract at ADS

Title: A High-Resolution Study of the Structure of Sunspot Light
    Bridges and Abnormal Granulation
Authors: Sobotka, Michal; Bonet, Jose A.; Vazquez, Manuel
Bibcode: 1994ApJ...426..404S
Altcode:
  Strong light bridges (SLBs) represent an abrupt change in the physical
  conditions of sunspot umbrae. They divide the umbra into separate units
  (fragments, umbral cores) and very often show a granular structure. A
  photometric and spectroscopic study of SLBs, and also of abnormal
  granulation (AG) in a region of pores, is presented. Slit-jaw images
  (bandpass 5425 +/- 50 A) and spectra (line Fe I 5434.5 A), with a
  spatial resolution of 0.3 sec, were acquired during the period 1991 July
  1-10 at the Swedish Solar Telescope at the Observatorio del Roque de
  los Muchachos (La Palma). The power spectra of intensity fluctuations
  in the slit-jaw images, were used as the primary diagnostic tool,
  complemented by the analysis of line profiles. The following results
  were obtained. 1. The structures present in SLBs and AG are generally
  smaller than the granules in the quiet photosphere. The typical size
  of SLB granules is 1.2 sec (in quiet granulation, 1.5 sec). In AG, the
  distribution of power is more complex and is characterized by peaks
  corresponding to scales of 2.5 sec, 1.3 sec, and 0.64 sec. 2. SLB
  and AG power spectra show an excess of power (compared to quiet
  granulation) at scales of 0.5 sec. This power enhancement reflects
  the presence of small bright grains, clearly visible in SLBs and AG,
  with a mean nearest neighbor distance of 0.5 sec. 3. Two of these small
  bright grains, together with a dark lane between them, were resolved
  spectroscopically in a SLB. The line shifts and bisector shapes suggest
  a convective origin of these structures. 4. The SLB power spectra in
  the log P/log k scale indicate the presence of a Kolmogorov turbulent
  cascade in the structures between 1.7 sec and 0.64 sec. However, the
  small bright grains do not pertain to the turbulent cascade. They
  are particular phenomena, probably with a convective origin. The
  power spectrum of AG does not give any indication of the presence of
  a turbulent cascade. 5. Small bright features (umbral dots or bright
  grains) can be found in unbral cores, light bridges, and AG regions as
  well. &lt;Their mean nearest neighbor distance, in the observed areas,
  decreases with increasing brightness and decreasing magnetic field
  strength. &amp;We thus propose that they are a manifestation of altered
  convection, which is modulated and maintained by the magnetic field.

Title: Spatially highly resolved time series of solar granulation
    spectra.
Authors: Hanslmeier, A.; Bonet, J. A.; Vazquez, M.
Bibcode: 1994AGAb...10..114H
Altcode:
  No abstract at ADS

Title: Active Compensation of Global Wavefront Tilts at Solar
Telescopes: Present Status of an Electronic Development
Authors: Ballesteros, E.; Viera, T.; Lorenzo, F.; Reyes, M.; Bonet,
   J. A.; Martin, C.
Bibcode: 1994ASIC..423..249B
Altcode: 1994aoa..conf..249B
  No abstract at ADS

Title: Strong light bridges and abnormal granulation
Authors: Sobotka, M.; Bonet, J. A.; Vázquez, M.
Bibcode: 1994smf..conf..197S
Altcode:
  No abstract at ADS

Title: A Solar Correlation Tracker Using a Video Motion Estimation
    Processor
Authors: Ballesteros, E.; Bonet, J. A.; Martin, C.; Fuentes, F. J.;
   Lorenzo, F.; Manescau, A.; Viera, T.; Diaz, J. J.; Joven, E.
Bibcode: 1993rtpf.conf...44B
Altcode:
  No abstract at ADS

Title: A High-Resolution Study of Inhomogeneities in Sunspot Umbrae
Authors: Sobotka, Michal; Bonet, Jose A.; Vazquez, Manuel
Bibcode: 1993ApJ...415..832S
Altcode:
  A detailed study of the brightness, size, spatial distribution,
  and filling factor of the different umbral inhomogeneities is
  presented. Many sunspots show multiple umbrae (separated by strong
  light bridges, SLBs), which behave like independent units. These are
  termed umbral cores (UCs). From the phenomenological point of view, UCs
  show two components: (1) a dark area, formed by a diffuse background
  (DB), with local intensity minima called dark nuclei (DNs), and (2)
  bright features including umbral dots (UDs) and faint light bridges
  (FLBs). <P />Slit-jaw images (bandpass 5425±50 Å) and spectra
  (line Fe I 5434.5 Å) of seven sunspots with 13 separate UCs were
  acquired using the Swedish Solar Telescope at the Observatorio
  del Roque de los Muchachos (La Palma) with a spatial resolution of
  0".3. Image restoration and inversion of the spectral line profile
  were applied, with the following results: <P />The most important
  photometric parameter of the UCs is the mean intensity of their DB
  (mean background intensity ‾I<SUB>back</SUB>). It is well correlated
  to the intensity minimum of the diffuse background and to the mean
  brightness of UDs. The relation between the size of the UCs and their
  ‾I<SUB>back</SUB> is not straightforward, but UCs with radii &lt;5"
  are in general brighter than the larger ones. The differences in the
  brightness of individual umbrae can be explained mainly by variations
  of ‾I<SUB>back</SUB> rather than in terms of variations of UD filling
  factor. <P />The linear relation between the peak intensity of UDs
  and the intensity of the adjacent DB (local background intensity)
  was confirmed in a sample of more than 1500 elements, and the
  "true" peak-to-background ratio was estimated as 3. <P />The spatial
  distribution of UDs is nonuniform. In DNs (whose size is comparable to
  that of photospheric granules) UDs appear very rarely; they prefer to
  form clusters and alignments outside the DNs. The mean nearest neighbor
  distance decreases, and the density of UDs increases with increasing
  ‾I<SUB>back</SUB>. The filling factor of UDs is in the range 3%-10%,
  and the size of UDs is similar in all UCs. The typical "true" size is
  180-300 km, and it is uncorrelated to the peak brightness of UDs. <P
  />FLBs are composed of bright grains and dark spaces between them. The
  bright grains are darker than photospheric granules. The size of the
  bright grains is similar to that of UDs, and their relative area in
  FLBs is very close to the fractional area granulum-intergranulum in the
  quiet photosphere. <P />On the basis of the obtained spectral profiles,
  working models of temperature stratification are presented for UDs,
  their adjacent DB, and DNs. <P />On the basis of observational facts
  the following is proposed: UDs and FLBs are probably demonstrations
  of some kind of altered convection, with a cell size of about 0".5,
  modulated by a smoothly varying magnetic field.

Title: High Resolution Observations of Umbral Fine Structure
Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M.
Bibcode: 1993ASPC...46...20S
Altcode: 1993mvfs.conf...20S; 1993IAUCo.141...20S
  No abstract at ADS

Title: Spectroscopic determination of intensities of umbral bright
    features and adjacent background
Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M.
Bibcode: 1992A&A...260..437S
Altcode:
  Profiles of the Na I D doublet in three bright features (clusters
  of umbral dots), located in a relatively dark umbra, were analyzed
  by means of the 'local two-component modeling' to obtain the 'true'
  continuum intensities and temperatures of the bright features and
  their dark surroundings (background). The intensities of two central
  and one peripheral bright feature were 0.31 (background 0.11), 0.33
  (0.13), and 0.40 (0.17), respectively. For the ratio of the object and
  background intensity (assumed to be constant, but unknown until now)
  the value of 2.6 +/- 0.2 was obtained.

Title: On the relation between the intensities of bright features
    and the local background in sunspot umbrae
Authors: Sobotka, M.; Bonet, J. A.; Vazquez, M.
Bibcode: 1992A&A...257..757S
Altcode:
  A photometric study of umbral bright features (umbral dots, clusters
  of umbral dots, bright grains of light bridges) in sunspots is
  presented. It is based on white-light images taken with a CCD video
  camera driven by an automatic image selection system. A direct linear
  relation between the observed brightness of the features and that
  of the surrounding background areas has been found. To eliminate the
  influence of the seeing on this result, the radiative fluxes, which
  are much less sensitive to the image degradation, have been examined
  and an analogous relation has been found. Finally, a possible physical
  explanation is suggested.

Title: A possible correlation tracker for LEST.
Authors: Bonet, J. A.; Martin, C.; Ballesteros, E.; Fuentes, F. J.;
   Lorenzo, F.; Manescau, A.; Rodriguez, L. F.; Zadrozny, A.
Bibcode: 1992LFTR...51.....B
Altcode:
  This document presents a proposal for the design of the LEST correlation
  tracker prototype. The proposed correlator, based on the absolute
  differences algorithm, is built around the LSI L64720 (Video Motion
  Estimation Processor) chip. The performances of the tracker system are
  established according to the LEST specifications and the experience
  derived from similar programmes. The design for the optomechanical
  support system to test the correlation tracker is also included.

Title: A Possible Correlation Tracker for lest
Authors: Bonet, J. A.; Martin, C.; Ballesteros, E.; Fuentes, F. J.;
   Lorenzo, F.; Manescau, A.; Rodriguez, L. F.; Zadrozny, A.
Bibcode: 1992lest.rept....1B
Altcode:
  No abstract at ADS

Title: Asymmetries and shifts of the solar K I 7699 A line and
    possible evidence for gravity waves in the quiet photosphere
Authors: Bonet, J. A.; Marquez, I.; Vazquez, M.; Woehl, H.
Bibcode: 1991A&A...244..492B
Altcode:
  A computing code has been developed to simulate the center-to-limb
  variation (CLV) of the bisector's shape, and absolute wavelength
  shift of the core in strong photospheric lines. Observational results
  concerning these aspects are also reported for the K I 7699 line. In
  the numerical simulation, granulation is represented, as a first
  approximation, by means of the granular model by Nelson (1978). It
  appears that granulation alone does not reproduce the observations and
  thus some modification has to be implemented in the dynamical model
  employed. A good match to the observed CLV of the wavelength shift
  of the line core is achieved by adding two 8-min period gravity waves
  with horizontal wavelength of the granular scale, the only difference
  between them being the sign of their horizontal wavenumber. Changes
  in the phase difference between the oscillating parameters have a
  decisive influence on the result.

Title: The Limb Effect of the KI 769. 9 nm Line in Quiet Regions
Authors: Bonet, J. A.; Marquez, I.; Vázquez, M.
Bibcode: 1989ASIC..263..299B
Altcode: 1989ssg..conf..299B
  No abstract at ADS

Title: Temporal and center-to-limb variations of the K I 769.9 NM
    line profiles in quiet and active solar regions
Authors: Bonet, J. A.; Marquez, I.; Vazquez, M.; Woehl, H.
Bibcode: 1988A&A...198..322B
Altcode:
  The temporal and spatial behaviour of the K I 769.9 nm solar line are
  investigated using several series of high spectral resolution low-noise
  photoelectric scans obtained at Kitt Peak National Observatory in
  quiet and active (plages and sunspots) regions. Corrections due
  to the instrumental profile were applied to yield the best line
  shape. A systematic center-to-limb investigation of the behaviour
  of the line shape was performed in quiet regions. Power and phase
  spectra of the main parameters defining the line shape have also
  been determined. Within several umbrae at different cos θ positions,
  an inverse C-shape or even an "S"-shape of the bisectors was found.

Title: Center-to-Limb Variation of the Asymmetries of the K 7699 Å
    line in Solar Quiet and Active Regions
Authors: Bonet, J. A.; Marquez, I.; Vázquez, M.; Wöhl, H.
Bibcode: 1987rfsm.conf...32B
Altcode:
  No abstract at ADS

Title: On the Width Distribution of Penumbral Filaments in Sunspots
Authors: Bonet, J. A.; Ponz, J. D.; Vazquez, M.
Bibcode: 1982SoPh...77...69B
Altcode:
  The mean width and distribution of penumbral filaments of a sunspot have
  been estimated, using white light photographs obtained with a vacuum,
  Newtonian type, telescope. Three areas corresponding to the penumbra
  of a sunspot have been analysed. Data were collected during the solar
  eclipse of June 1973. The photometric profiles of the Moon limb over the
  photosphere have been analysed to obtain useful information on both,
  atmospheric and instrumental perturbation on each exposure. The mean
  value of the width of penumbral filaments is 0.37 arc sec.

Title: Aspectos magneticos de la evolucion de las manchas solares.
Authors: Casanovas, J.; Vazquez, M.; Bonet, J. A.
Bibcode: 1974UrBar..59...79C
Altcode:
  The spectroscopic determinations of the solar magnetic fields are based
  on the Zeeman effect observed in relation to a number of absorption
  lines of the solar spectrum. It is attempted to deduce indirectly
  certain characteristics of the magnetic field in a sunspot, giving
  attention to morphological aspects and the magnetic polarities. The
  results of the investigation are illustrated with the aid of a number
  of pictures.

