Author name code: staude
ADS astronomy entries on 2022-09-14
author:"Staude, Juergen" 
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Title: Spectropolarimetric Observations of an Arch Filament System
    with GREGOR
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
   Kuckein, C.; Kučera, A.; Schwartz, P.; Berkefeld, T.; Collados, M.;
   Denker, C.; Feller, A.; Hofmann, A.; Schlichenmaier, R.; Schmidt,
   D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau,
   D.; Staude, J.; Strassmeier, K. G.; von der Lühe, O.
Bibcode: 2019ASPC..526..217B
Altcode: 2018arXiv180401789B
  We observed an arch filament system (AFS) in a sunspot group with the
  GREGOR Infrared Spectrograph attached to the GREGOR solar telescope. The
  AFS was located between the leading sunspot of negative polarity and
  several pores of positive polarity forming the following part of the
  sunspot group. We recorded five spectro-polarimetric scans of this
  region. The spectral range included the spectral lines Si I 1082.7
  nm, He I 1083.0 nm, and Ca I 1083.9 nm. In this work we concentrate
  on the silicon line which is formed in the upper photosphere. The
  line profiles are inverted with the code 'Stokes Inversion based
  on Response functions' to obtain the magnetic field vector. The
  line-of-sight velocities are determined independently with a Fourier
  phase method. Maximum velocities are found close to the ends of AFS
  fibrils. These maximum values amount to 2.4 km s<SUP>-1</SUP> next
  to the pores and to 4 km s<SUP>-1</SUP> at the sunspot side. Between
  the following pores, we encounter an area of negative polarity that
  is decreasing during the five scans. We interpret this by new emerging
  positive flux in this area canceling out the negative flux. In summary,
  our findings confirm the scenario that rising magnetic flux tubes
  cause the AFS.

Title: Photospheric Magnetic Fields of the Trailing Sunspots in
    Active Region NOAA 12396
Authors: Verma, M.; Balthasar, H.; Denker, C.; Böhm, F.; Fischer,
   C. E.; Kuckein, C.; González Manrique, S. J.; Sobotka, M.; Bello
   González, N.; Diercke, A.; Berkefeld, T.; Collados, M.; Feller, A.;
   Hofmann, A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar,
   A.; Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
   M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K.; Volkmer,
   R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2019ASPC..526..291V
Altcode: 2018arXiv180507752V
  The solar magnetic field is responsible for all aspects of solar
  activity. Sunspots are the main manifestation of the ensuing solar
  activity. Combining high-resolution and synoptic observations has
  the ambition to provide a comprehensive description of the sunspot
  growth and decay processes. Active region NOAA 12396 emerged on 2015
  August 3 and was observed three days later with the 1.5-meter GREGOR
  solar telescope on 2015 August 6. High-resolution spectropolarimetric
  data from the GREGOR Infrared Spectrograph (GRIS) are obtained in the
  photospheric lines Si I λ1082.7 nm and Ca I λ1083.9 nm, together
  with the chromospheric He I λ1083.0 nm triplet. These near-infrared
  spectropolarimetric observations were complemented by synoptic
  line-of-sight magnetograms and continuum images of the Helioseismic
  and Magnetic Imager (HMI) and EUV images of the Atmospheric Imaging
  Assembly (AIA) on board the Solar Dynamics Observatory (SDO).

Title: Flows along arch filaments observed in the GRIS `very fast
    spectroscopic mode'
Authors: González Manrique, S. J.; Denker, C.; Kuckein, C.; Pastor
   Yabar, A.; Collados, M.; Verma, M.; Balthasar, H.; Diercke, A.;
   Fischer, C. E.; Gömöry, P.; Bello González, N.; Schlichenmaier,
   R.; Cubas Armas, M.; Berkefeld, T.; Feller, A.; Hoch, S.; Hofmann,
   A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Schmidt, D.; Schmidt,
   W.; Sigwarth, M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude,
   J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2017IAUS..327...28G
Altcode: 2017arXiv170102206G
  A new generation of solar instruments provides improved spectral,
  spatial, and temporal resolution, thus facilitating a better
  understanding of dynamic processes on the Sun. High-resolution
  observations often reveal multiple-component spectral line profiles,
  e.g., in the near-infrared He i 10830 Å triplet, which provides
  information about the chromospheric velocity and magnetic fine
  structure. We observed an emerging flux region, including two small
  pores and an arch filament system, on 2015 April 17 with the `very
  fast spectroscopic mode' of the GREGOR Infrared Spectrograph (GRIS)
  situated at the 1.5-meter GREGOR solar telescope at Observatorio del
  Teide, Tenerife, Spain. We discuss this method of obtaining fast (one
  per minute) spectral scans of the solar surface and its potential to
  follow dynamic processes on the Sun. We demonstrate the performance
  of the `very fast spectroscopic mode' by tracking chromospheric
  high-velocity features in the arch filament system.

Title: Slipping reconnection in a solar flare observed in high
    resolution with the GREGOR solar telescope
Authors: Sobotka, M.; Dudík, J.; Denker, C.; Balthasar, H.; Jurčák,
   J.; Liu, W.; Berkefeld, T.; Collados Vera, M.; Feller, A.; Hofmann,
   A.; Kneer, F.; Kuckein, C.; Lagg, A.; Louis, R. E.; von der Lühe, O.;
   Nicklas, H.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
   M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.;
   Volkmer, R.; Waldmann, T.
Bibcode: 2016A&A...596A...1S
Altcode: 2016arXiv160500464S
  A small flare ribbon above a sunspot umbra in active region 12205 was
  observed on November 7, 2014, at 12:00 UT in the blue imaging channel
  of the 1.5 m GREGOR telescope, using a 1 Å Ca II H interference
  filter. Context observations from the Atmospheric Imaging Assembly
  (AIA) onboard the Solar Dynamics Observatory (SDO), the Solar Optical
  Telescope (SOT) onboard Hinode, and the Interface Region Imaging
  Spectrograph (IRIS) show that this ribbon is part of a larger one
  that extends through the neighboring positive polarities and also
  participates in several other flares within the active region. We
  reconstructed a time series of 140 s of Ca II H images by means of the
  multiframe blind deconvolution method, which resulted in spatial and
  temporal resolutions of 0.1″ and 1 s. Light curves and horizontal
  velocities of small-scale bright knots in the observed flare ribbon
  were measured. Some knots are stationary, but three move along the
  ribbon with speeds of 7-11 km s<SUP>-1</SUP>. Two of them move in the
  opposite direction and exhibit highly correlated intensity changes,
  which provides evidence of a slipping reconnection at small spatial
  scales. <P />Movies associated to Figs. 1 and 2 are available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201527966/olm">http://www.aanda.org</A>

Title: Deep probing of the photospheric sunspot penumbra: no evidence
    of field-free gaps
Authors: Borrero, J. M.; Asensio Ramos, A.; Collados, M.;
   Schlichenmaier, R.; Balthasar, H.; Franz, M.; Rezaei, R.; Kiess, C.;
   Orozco Suárez, D.; Pastor Yabar, A.; Berkefeld, T.; von der Lühe,
   O.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Soltau, D.; Volkmer, R.;
   Waldmann, T.; Denker, C.; Hofmann, A.; Staude, J.; Strassmeier, K. G.;
   Feller, A.; Lagg, A.; Solanki, S. K.; Sobotka, M.; Nicklas, H.
Bibcode: 2016A&A...596A...2B
Altcode: 2016arXiv160708165B
  Context. Some models for the topology of the magnetic field in
  sunspot penumbrae predict regions free of magnetic fields or with
  only dynamically weak fields in the deep photosphere. <BR /> Aims:
  We aim to confirm or refute the existence of weak-field regions in
  the deepest photospheric layers of the penumbra. <BR /> Methods:
  We investigated the magnetic field at log τ<SUB>5</SUB> = 0 is
  by inverting spectropolarimetric data of two different sunspots
  located very close to disk center with a spatial resolution of
  approximately 0.4-0.45''. The data have been recorded using the GRIS
  instrument attached to the 1.5-m solar telescope GREGOR at the El
  Teide observatory. The data include three Fe I lines around 1565 nm,
  whose sensitivity to the magnetic field peaks half a pressure scale
  height deeper than the sensitivity of the widely used Fe I spectral
  line pair at 630 nm. Before the inversion, the data were corrected
  for the effects of scattered light using a deconvolution method with
  several point spread functions. <BR /> Results: At log τ<SUB>5</SUB>
  = 0 we find no evidence of regions with dynamically weak (B&lt;
  500 Gauss) magnetic fields in sunspot penumbrae. This result is much
  more reliable than previous investigations made on Fe I lines at 630
  nm. Moreover, the result is independent of the number of nodes employed
  in the inversion, is independent of the point spread function used to
  deconvolve the data, and does not depend on the amount of stray light
  (I.e., wide-angle scattered light) considered.

Title: Spectropolarimetric observations of an arch filament system
    with the GREGOR solar telescope
Authors: Balthasar, H.; Gömöry, P.; González Manrique, S. J.;
   Kuckein, C.; Kavka, J.; Kučera, A.; Schwartz, P.; Vašková, R.;
   Berkefeld, T.; Collados Vera, M.; Denker, C.; Feller, A.; Hofmann,
   A.; Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pastor Yabar, A.;
   Rezaei, R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth,
   M.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1050B
Altcode: 2016arXiv160901514B
  Arch filament systems occur in active sunspot groups, where a fibril
  structure connects areas of opposite magnetic polarity, in contrast to
  active region filaments that follow the polarity inversion line. We
  used the GREGOR Infrared Spectrograph (GRIS) to obtain the full
  Stokes vector in the spectral lines Si I λ1082.7 nm, He I λ1083.0
  nm, and Ca I λ1083.9 nm. We focus on the near-infrared calcium line
  to investigate the photospheric magnetic field and velocities, and
  use the line core intensities and velocities of the helium line to
  study the chromospheric plasma. The individual fibrils of the arch
  filament system connect the sunspot with patches of magnetic polarity
  opposite to that of the spot. These patches do not necessarily coincide
  with pores, where the magnetic field is strongest. Instead, areas are
  preferred not far from the polarity inversion line. These areas exhibit
  photospheric downflows of moderate velocity, but significantly higher
  downflows of up to 30 km s<SUP>-1</SUP> in the chromospheric helium
  line. Our findings can be explained with new emerging flux where the
  matter flows downward along the field lines of rising flux tubes,
  in agreement with earlier results.

Title: Magnetic fields of opposite polarity in sunspot penumbrae
Authors: Franz, M.; Collados, M.; Bethge, C.; Schlichenmaier, R.;
   Borrero, J. M.; Schmidt, W.; Lagg, A.; Solanki, S. K.; Berkefeld,
   T.; Kiess, C.; Rezaei, R.; Schmidt, D.; Sigwarth, M.; Soltau, D.;
   Volkmer, R.; von der Luhe, O.; Waldmann, T.; Orozco, D.; Pastor Yabar,
   A.; Denker, C.; Balthasar, H.; Staude, J.; Hofmann, A.; Strassmeier,
   K.; Feller, A.; Nicklas, H.; Kneer, F.; Sobotka, M.
Bibcode: 2016A&A...596A...4F
Altcode: 2016arXiv160800513F
  Context. A significant part of the penumbral magnetic field returns
  below the surface in the very deep photosphere. For lines in the
  visible, a large portion of this return field can only be detected
  indirectly by studying its imprints on strongly asymmetric and
  three-lobed Stokes V profiles. Infrared lines probe a narrow layer
  in the very deep photosphere, providing the possibility of directly
  measuring the orientation of magnetic fields close to the solar
  surface. <BR /> Aims: We study the topology of the penumbral magnetic
  field in the lower photosphere, focusing on regions where it returns
  below the surface. <BR /> Methods: We analyzed 71 spectropolarimetric
  datasets from Hinode and from the GREGOR infrared spectrograph. We
  inferred the quality and polarimetric accuracy of the infrared data
  after applying several reduction steps. Techniques of spectral
  inversion and forward synthesis were used to test the detection
  algorithm. We compared the morphology and the fractional penumbral
  area covered by reversed-polarity and three-lobed Stokes V profiles for
  sunspots at disk center. We determined the amount of reversed-polarity
  and three-lobed Stokes V profiles in visible and infrared data of
  sunspots at various heliocentric angles. From the results, we computed
  center-to-limb variation curves, which were interpreted in the context
  of existing penumbral models. <BR /> Results: Observations in visible
  and near-infrared spectral lines yield a significant difference in the
  penumbral area covered by magnetic fields of opposite polarity. In
  the infrared, the number of reversed-polarity Stokes V profiles is
  smaller by a factor of two than in the visible. For three-lobed Stokes
  V profiles the numbers differ by up to an order of magnitude.

Title: Horizontal flow fields in and around a small active region. The
    transition period between flux emergence and decay
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
   Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
   A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
   A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
   Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
   M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016A&A...596A...3V
Altcode: 2016arXiv160507462V
  Context. The solar magnetic field is responsible for all aspects
  of solar activity. Thus, emergence of magnetic flux at the surface
  is the first manifestation of the ensuing solar activity. <BR />
  Aims: Combining high-resolution and synoptic observations aims to
  provide a comprehensive description of flux emergence at photospheric
  level and of the growth process that eventually leads to a mature
  active region. <BR /> Methods: The small active region NOAA 12118
  emerged on 2014 July 17 and was observed one day later with the 1.5-m
  GREGOR solar telescope on 2014 July 18. High-resolution time-series
  of blue continuum and G-band images acquired in the blue imaging
  channel (BIC) of the GREGOR Fabry-Pérot Interferometer (GFPI) were
  complemented by synoptic line-of-sight magnetograms and continuum
  images obtained with the Helioseismic and Magnetic Imager (HMI) onboard
  the Solar Dynamics Observatory (SDO). Horizontal proper motions and
  horizontal plasma velocities were computed with local correlation
  tracking (LCT) and the differential affine velocity estimator (DAVE),
  respectively. Morphological image processing was employed to measure
  the photometric and magnetic area, magnetic flux, and the separation
  profile of the emerging flux region during its evolution. <BR />
  Results: The computed growth rates for photometric area, magnetic
  area, and magnetic flux are about twice as high as the respective
  decay rates. The space-time diagram using HMI magnetograms of five days
  provides a comprehensive view of growth and decay. It traces a leaf-like
  structure, which is determined by the initial separation of the two
  polarities, a rapid expansion phase, a time when the spread stalls,
  and a period when the region slowly shrinks again. The separation
  rate of 0.26 km s<SUP>-1</SUP> is highest in the initial stage, and
  it decreases when the separation comes to a halt. Horizontal plasma
  velocities computed at four evolutionary stages indicate a changing
  pattern of inflows. In LCT maps we find persistent flow patterns such
  as outward motions in the outer part of the two major pores, a diverging
  feature near the trailing pore marking the site of upwelling plasma and
  flux emergence, and low velocities in the interior of dark pores. We
  detected many elongated rapidly expanding granules between the two
  major polarities, with dimensions twice as large as the normal granules.

Title: Solar physics at the Einstein Tower
Authors: Denker, C.; Heibel, C.; Rendtel, J.; Arlt, K.; Balthasar,
   Juergen H.; Diercke, A.; González Manrique, S. J.; Hofmann, A.;
   Kuckein, C.; Önel, H.; Senthamizh Pavai, V.; Staude, J.; Verman, M.
Bibcode: 2016AN....337.1105D
Altcode: 2016arXiv160906949D
  The solar observatory Einstein Tower ({Einsteinturm}) at the
  Telegrafenberg in Potsdam is both a landmark of modern architecture
  and an important place for solar physics. Originally built for
  high-resolution spectroscopy and measuring the gravitational redshift,
  research shifted over the years to understanding the active Sun and
  its magnetic field. Nowadays, telescope and spectrographs are used for
  research and development, i.e., testing instruments and in particular
  polarization optics for advanced instrumentation deployed at major
  European and international astronomical and solar telescopes. In
  addition, the Einstein Tower is used for educating and training of the
  next generation astrophysicists as well as for education and public
  outreach activities directed at the general public. This article
  comments on the observatory's unique architecture and the challenges
  of maintaining and conserving the building. It describes in detail the
  characteristics of telescope, spectrographs, and imagers; it portrays
  some of the research and development activities.

Title: Upper chromospheric magnetic field of a sunspot penumbra:
    observations of fine structure
Authors: Joshi, J.; Lagg, A.; Solanki, S. K.; Feller, A.; Collados,
   M.; Orozco Suárez, D.; Schlichenmaier, R.; Franz, M.; Balthasar,
   H.; Denker, C.; Berkefeld, T.; Hofmann, A.; Kiess, C.; Nicklas, H.;
   Pastor Yabar, A.; Rezaei, R.; Schmidt, D.; Schmidt, W.; Sobotka, M.;
   Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; von der Lühe,
   O.; Waldmann, T.
Bibcode: 2016A&A...596A...8J
Altcode: 2016arXiv160801988J
  <BR /> Aims: The fine-structure of the magnetic field in a sunspot
  penumbra in the upper chromosphere is to be explored and compared
  to that in the photosphere. <BR /> Methods: Spectropolarimetric
  observations with high spatial resolution were recorded with the 1.5-m
  GREGOR telescope using the GREGOR Infrared Spectrograph (GRIS). The
  observed spectral domain includes the upper chromospheric Hei triplet
  at 10 830 Å and the photospheric Sii 10 827.1 Å and Cai 10 833.4 Å
  spectral lines. The upper chromospheric magnetic field is obtained
  by inverting the Hei triplet assuming a Milne-Eddington-type model
  atmosphere. A height-dependent inversion was applied to the Sii 10
  827.1 Å and Cai 10 833.4 Å lines to obtain the photospheric magnetic
  field. <BR /> Results: We find that the inclination of the magnetic
  field varies in the azimuthal direction in the photosphere and in the
  upper chromosphere. The chromospheric variations coincide remarkably
  well with the variations in the inclination of the photospheric field
  and resemble the well-known spine and interspine structure in the
  photospheric layers of penumbrae. The typical peak-to-peak variations
  in the inclination of the magnetic field in the upper chromosphere
  are found to be 10°-15°, which is roughly half the variation in
  the photosphere. In contrast, the magnetic field strength of the
  observed penumbra does not vary on small spatial scales in the upper
  chromosphere. <BR /> Conclusions: Thanks to the high spatial resolution
  of the observations that is possible with the GREGOR telescope at 1.08
  microns, we find that the prominent small-scale fluctuations in the
  magnetic field inclination, which are a salient part of the property
  of sunspot penumbral photospheres, also persist in the chromosphere,
  although at somewhat reduced amplitudes. Such a complex magnetic
  configuration may facilitate penumbral chromospheric dynamic phenomena,
  such as penumbral micro-jets or transient bright dots.

Title: Active region fine structure observed at 0.08 arcsec resolution
Authors: Schlichenmaier, R.; von der Lühe, O.; Hoch, S.; Soltau, D.;
   Berkefeld, T.; Schmidt, D.; Schmidt, W.; Denker, C.; Balthasar, H.;
   Hofmann, A.; Strassmeier, K. G.; Staude, J.; Feller, A.; Lagg, A.;
   Solanki, S. K.; Collados, M.; Sigwarth, M.; Volkmer, R.; Waldmann,
   T.; Kneer, F.; Nicklas, H.; Sobotka, M.
Bibcode: 2016A&A...596A...7S
Altcode: 2016arXiv160707094S
  Context. The various mechanisms of magneto-convective energy transport
  determine the structure of sunspots and active regions. <BR />
  Aims: We characterise the appearance of light bridges and other
  fine-structure details and elaborate on their magneto-convective
  nature. <BR /> Methods: We present speckle-reconstructed images taken
  with the broad-band imager (BBI) at the 1.5 m GREGOR telescope in the
  486 nm and 589 nm bands. We estimate the spatial resolution from the
  noise characteristics of the image bursts and obtain 0.08″ at 589
  nm. We describe structure details in individual best images as well
  as the temporal evolution of selected features. <BR /> Results: We
  find branched dark lanes extending along thin (≈1″) light bridges
  in sunspots at various heliocentric angles. In thick (≳ 2″) light
  bridges the branches are disconnected from the central lane and have a Y
  shape with a bright grain toward the umbra. The images reveal that light
  bridges exist on varying intensity levels and that their small-scale
  features evolve on timescales of minutes. Faint light bridges show
  dark lanes outlined by the surrounding bright features. Dark lanes are
  very common and are also found in the boundary of pores. They have a
  characteristic width of 0.1″ or smaller. Intergranular dark lanes of
  that width are seen in active region granulation. <BR /> Conclusions: We
  interpret our images in the context of magneto-convective simulations
  and findings: while central dark lanes in thin light bridges are
  elevated and associated with a density increase above upflows, the dark
  lane branches correspond to locations of downflows and are depressed
  relative to the adjacent bright plasma. Thick light bridges with central
  dark lanes show no projection effect. They have a flat elevated plateau
  that falls off steeply at the umbral boundary. There, Y-shaped filaments
  form as they do in the inner penumbra. This indicates the presence of
  inclined magnetic fields, meaning that the umbral magnetic field is
  wrapped around the convective light bridge.

Title: Probing deep photospheric layers of the quiet Sun with high
    magnetic sensitivity
Authors: Lagg, A.; Solanki, S. K.; Doerr, H. -P.; Martínez González,
   M. J.; Riethmüller, T.; Collados Vera, M.; Schlichenmaier, R.;
   Orozco Suárez, D.; Franz, M.; Feller, A.; Kuckein, C.; Schmidt, W.;
   Asensio Ramos, A.; Pastor Yabar, A.; von der Lühe, O.; Denker, C.;
   Balthasar, H.; Volkmer, R.; Staude, J.; Hofmann, A.; Strassmeier,
   K.; Kneer, F.; Waldmann, T.; Borrero, J. M.; Sobotka, M.; Verma, M.;
   Louis, R. E.; Rezaei, R.; Soltau, D.; Berkefeld, T.; Sigwarth, M.;
   Schmidt, D.; Kiess, C.; Nicklas, H.
Bibcode: 2016A&A...596A...6L
Altcode: 2016arXiv160506324L
  Context. Investigations of the magnetism of the quiet Sun are hindered
  by extremely weak polarization signals in Fraunhofer spectral
  lines. Photon noise, straylight, and the systematically different
  sensitivity of the Zeeman effect to longitudinal and transversal
  magnetic fields result in controversial results in terms of the strength
  and angular distribution of the magnetic field vector. <BR /> Aims:
  The information content of Stokes measurements close to the diffraction
  limit of the 1.5 m GREGOR telescope is analyzed. We took the effects of
  spatial straylight and photon noise into account. <BR /> Methods: Highly
  sensitive full Stokes measurements of a quiet-Sun region at disk center
  in the deep photospheric Fe I lines in the 1.56 μm region were obtained
  with the infrared spectropolarimeter GRIS at the GREGOR telescope. Noise
  statistics and Stokes V asymmetries were analyzed and compared to a
  similar data set of the Hinode spectropolarimeter (SOT/SP). Simple
  diagnostics based directly on the shape and strength of the profiles
  were applied to the GRIS data. We made use of the magnetic line ratio
  technique, which was tested against realistic magneto-hydrodynamic
  simulations (MURaM). <BR /> Results: About 80% of the GRIS spectra
  of a very quiet solar region show polarimetric signals above a 3σ
  level. Area and amplitude asymmetries agree well with small-scale
  surface dynamo-magneto hydrodynamic simulations. The magnetic line ratio
  analysis reveals ubiquitous magnetic regions in the ten to hundred Gauss
  range with some concentrations of kilo-Gauss fields. <BR /> Conclusions:
  The GRIS spectropolarimetric data at a spatial resolution of ≈0.̋4
  are so far unique in the combination of high spatial resolution scans
  and high magnetic field sensitivity. Nevertheless, the unavoidable
  effect of spatial straylight and the resulting dilution of the weak
  Stokes profiles means that inversion techniques still bear a high risk
  of misinterpretating the data.

Title: Flow and magnetic field properties in the trailing sunspots
    of active region NOAA 12396
Authors: Verma, M.; Denker, C.; Böhm, F.; Balthasar, H.; Fischer,
   C. E.; Kuckein, C.; Bello González, N.; Berkefeld, T.; Collados,
   M.; Diercke, A.; Feller, A.; González Manrique, S. J.; Hofmann, A.;
   Lagg, A.; Nicklas, H.; Orozco Suárez, D.; Pator Yabar, A.; Rezaei,
   R.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.;
   Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K. G.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1090V
Altcode:
  Improved measurements of the photospheric and chromospheric
  three-dimensional magnetic and flow fields are crucial for a precise
  determination of the origin and evolution of active regions. We present
  an illustrative sample of multi-instrument data acquired during a
  two-week coordinated observing campaign in August 2015 involving,
  among others, the GREGOR solar telescope (imaging and near-infrared
  spectroscopy) and the space missions Solar Dynamics Observatory (SDO)
  and Interface Region Imaging Spectrograph (IRIS). The observations
  focused on the trailing part of active region NOAA 12396 with complex
  polarity inversion lines and strong intrusions of opposite polarity
  flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV
  spectral profiles in the photospheric Si I λ1082.7 nm line, the
  chromospheric He I λ1083.0 nm triplet, and the photospheric Ca I
  λ1083.9 nm line. Carefully calibrated GRIS scans of the active region
  provided maps of Doppler velocity and magnetic field at different
  atmospheric heights. We compare quick-look maps with those obtained
  with the ``Stokes Inversions based on Response functions'' (SIR)
  code, which furnishes deeper insight into the magnetic properties
  of the region. We find supporting evidence that newly emerging flux
  and intruding opposite polarity flux are hampering the formation
  of penumbrae, i.e., a penumbra fully surrounding a sunspot is only
  expected after cessation of flux emergence in proximity to the sunspots.

Title: Three-dimensional structure of a sunspot light bridge
Authors: Felipe, T.; Collados, M.; Khomenko, E.; Kuckein, C.; Asensio
   Ramos, A.; Balthasar, H.; Berkefeld, T.; Denker, C.; Feller, A.;
   Franz, M.; Hofmann, A.; Joshi, J.; Kiess, C.; Lagg, A.; Nicklas, H.;
   Orozco Suárez, D.; Pastor Yabar, A.; Rezaei, R.; Schlichenmaier,
   R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka, M.; Solanki,
   S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.;
   von der Lühe, O.; Waldmann, T.
Bibcode: 2016A&A...596A..59F
Altcode: 2016arXiv161104803F
  Context. Active regions are the most prominent manifestations of solar
  magnetic fields; their generation and dissipation are fundamental
  problems in solar physics. Light bridges are commonly present during
  sunspot decay, but a comprehensive picture of their role in the
  removal of the photospheric magnetic field is still lacking. <BR />
  Aims: We study the three-dimensional configuration of a sunspot,
  and in particular, its light bridge, during one of the last stages of
  its decay. <BR /> Methods: We present the magnetic and thermodynamical
  stratification inferred from full Stokes inversions of the photospheric
  Si I 10 827 Å and Ca I 10 839 Å lines obtained with the GREGOR
  Infrared Spectrograph of the GREGOR telescope at the Observatorio del
  Teide, Tenerife, Spain. The analysis is complemented by a study of
  continuum images covering the disk passage of the active region, which
  are provided by the Helioseismic and Magnetic Imager on board the Solar
  Dynamics Observatory. <BR /> Results: The sunspot shows a light bridge
  with penumbral continuum intensity that separates the central umbra from
  a smaller umbra. We find that in this region the magnetic field lines
  form a canopy with lower magnetic field strength in the inner part. The
  photospheric light bridge is dominated by gas pressure (high-β),
  as opposed to the surrounding umbra, where the magnetic pressure
  is higher. A convective flow is observed in the light bridge. This
  flow is able to bend the magnetic field lines and to produce field
  reversals. The field lines merge above the light bridge and become
  as vertical and strong as in the surrounding umbra. We conclude that
  this occurs because two highly magnetized regions approach each other
  during the sunspot evolution. <P />Movies associated to Figs. 2 and 13
  are available at <A href="http://www.aanda.org">http://www.aanda.org</A>

Title: Inference of magnetic fields in the very quiet Sun
Authors: Martínez González, M. J.; Pastor Yabar, A.; Lagg, A.;
   Asensio Ramos, A.; Collados, M.; Solanki, S. K.; Balthasar, H.;
   Berkefeld, T.; Denker, C.; Doerr, H. P.; Feller, A.; Franz, M.;
   González Manrique, S. J.; Hofmann, A.; Kneer, F.; Kuckein, C.;
   Louis, R.; von der Lühe, O.; Nicklas, H.; Orozco, D.; Rezaei, R.;
   Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
   M.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma, M.; Waldman,
   T.; Volkmer, R.
Bibcode: 2016A&A...596A...5M
Altcode: 2018arXiv180410089M
  Context. Over the past 20 yr, the quietest areas of the solar surface
  have revealed a weak but extremely dynamic magnetism occurring
  at small scales (&lt;500 km), which may provide an important
  contribution to the dynamics and energetics of the outer layers of
  the atmosphere. Understanding this magnetism requires the inference
  of physical quantities from high-sensitivity spectro-polarimetric
  data with high spatio-temporal resolution. <BR /> Aims: We present
  high-precision spectro-polarimetric data with high spatial resolution
  (0.4'') of the very quiet Sun at 1.56 μm obtained with the GREGOR
  telescope to shed some light on this complex magnetism. <BR /> Methods:
  We used inversion techniques in two main approaches. First, we assumed
  that the observed profiles can be reproduced with a constant magnetic
  field atmosphere embedded in a field-free medium. Second, we assumed
  that the resolution element has a substructure with either two constant
  magnetic atmospheres or a single magnetic atmosphere with gradients of
  the physical quantities along the optical depth, both coexisting with
  a global stray-light component. <BR /> Results: Half of our observed
  quiet-Sun region is better explained by magnetic substructure within
  the resolution element. However, we cannot distinguish whether this
  substructure comes from gradients of the physical parameters along the
  line of sight or from horizontal gradients (across the surface). In
  these pixels, a model with two magnetic components is preferred, and
  we find two distinct magnetic field populations. The population with
  the larger filling factor has very weak ( 150 G) horizontal fields
  similar to those obtained in previous works. We demonstrate that the
  field vector of this population is not constrained by the observations,
  given the spatial resolution and polarimetric accuracy of our data. The
  topology of the other component with the smaller filling factor is
  constrained by the observations for field strengths above 250 G:
  we infer hG fields with inclinations and azimuth values compatible
  with an isotropic distribution. The filling factors are typically
  below 30%. We also find that the flux of the two polarities is not
  balanced. From the other half of the observed quiet-Sun area 50% are
  two-lobed Stokes V profiles, meaning that 23% of the field of view
  can be adequately explained with a single constant magnetic field
  embedded in a non-magnetic atmosphere. The magnetic field vector and
  filling factor are reliable inferred in only 50% based on the regular
  profiles. Therefore, 12% of the field of view harbour hG fields with
  filling factors typically below 30%. At our present spatial resolution,
  70% of the pixels apparently are non-magnetised.

Title: Fitting peculiar spectral profiles in He I 10830Å absorption
    features
Authors: González Manrique, S. J.; Kuckein, C.; Pastor Yabar, A.;
   Collados, M.; Denker, C.; Fischer, C. E.; Gömöry, P.; Diercke, A.;
   Bello González, N.; Schlichenmaier, R.; Balthasar, H.; Berkefeld, T.;
   Feller, A.; Hoch, S.; Hofmann, A.; Kneer, F.; Lagg, A.; Nicklas, H.;
   Orozco Suárez, D.; Schmidt, D.; Schmidt, W.; Sigwarth, M.; Sobotka,
   M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; Verma,
   M.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016AN....337.1057G
Altcode: 2016arXiv160300679G
  The new generation of solar instruments provides better
  spectral, spatial, and temporal resolution for a better
  understanding of the physical processes that take place on the
  Sun. Multiple-component profiles are more commonly observed with these
  instruments. Particularly, the He I 10830 Å triplet presents such
  peculiar spectral profiles, which give information on the velocity
  and magnetic fine structure of the upper chromosphere. The purpose
  of this investigation is to describe a technique to efficiently fit
  the two blended components of the He I 10830 Å triplet, which are
  commonly observed when two atmospheric components are located within
  the same resolution element. The observations used in this study were
  taken on 2015 April 17 with the very fast spectroscopic mode of the
  GREGOR Infrared Spectrograph (GRIS) attached to the 1.5-m GREGOR solar
  telescope, located at the Observatorio del Teide, Tenerife, Spain. We
  apply a double-Lorentzian fitting technique using Levenberg-Marquardt
  least-squares minimization. This technique is very simple and much
  faster than inversion codes. Line-of-sight Doppler velocities can
  be inferred for a whole map of pixels within just a few minutes. Our
  results show sub- and supersonic downflow velocities of up to 32 km
  s<SUP>-1</SUP> for the fast component in the vicinity of footpoints of
  filamentary structures. The slow component presents velocities close
  to rest.

Title: Flows in and around Active Region NOAA12118 Observed with
    the GREGOR Solar Telescope and SDO/HMI
Authors: Verma, M.; Denker, C.; Balthasar, H.; Kuckein, C.; González
   Manrique, S. J.; Sobotka, M.; Bello González, N.; Hoch, S.; Diercke,
   A.; Kummerow, P.; Berkefeld, T.; Collados, M.; Feller, A.; Hofmann,
   A.; Kneer, F.; Lagg, A.; Löhner-Böttcher, J.; Nicklas, H.; Pastor
   Yabar, A.; Schlichenmaier, R.; Schmidt, D.; Schmidt, W.; Schubert,
   M.; Sigwarth, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier,
   K.; Volkmer, R.; von der Lühe, O.; Waldmann, T.
Bibcode: 2016ASPC..504...29V
Altcode: 2016arXiv160301109V
  Accurate measurements of magnetic and velocity fields in and around
  solar active regions are key to unlocking the mysteries of the
  formation and the decay of sunspots. High spatial resolution images
  and spectral sequences with a high cadence obtained with the GREGOR
  solar telescope give us an opportunity to scrutinize 3-D flow fields
  with local correlation tracking and imaging spectroscopy. We present
  GREGOR early science data acquired in 2014 July - August with the GREGOR
  Fabry-Pérot Interferometer and the Blue Imaging Channel. Time-series
  of blue continuum (λ 450.6 nm) images of the small active region
  NOAA 12118 were restored with the speckle masking technique to derive
  horizontal proper motions and to track the evolution of morphological
  changes. In addition, high-resolution observations are discussed in
  the context of synoptic data from the Solar Dynamics Observatory.

Title: A retrospective of the GREGOR solar telescope in scientific
    literature
Authors: Denker, C.; von der Lühe, O.; Feller, A.; Arlt, K.;
   Balthasar, H.; Bauer, S. -M.; Bello González, N.; Berkefeld, Th.;
   Caligari, P.; Collados, M.; Fischer, A.; Granzer, T.; Hahn, T.;
   Halbgewachs, C.; Heidecke, F.; Hofmann, A.; Kentischer, T.; Klva{ňa,
   M.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.;
   Rendtel, J.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Solanki, S. K.;
   Soltau, D.; Staude, J.; Strassmeier, K. G.; Volkmer, R.; Waldmann,
   T.; Wiehr, E.; Wittmann, A. D.; Woche, M.
Bibcode: 2012AN....333..810D
Altcode: 2012arXiv1210.3167D
  In this review, we look back upon the literature, which had the
  GREGOR solar telescope project as its subject including science cases,
  telescope subsystems, and post-focus instruments. The articles date
  back to the year 2000, when the initial concepts for a new solar
  telescope on Tenerife were first presented at scientific meetings. This
  comprehensive bibliography contains literature until the year 2012,
  i.e., the final stages of commissioning and science verification. Taking
  stock of the various publications in peer-reviewed journals and
  conference proceedings also provides the ``historical'' context
  for the reference articles in this special issue of Astronomische
  Nachrichten/Astronomical Notes.

Title: The 1.5 meter solar telescope GREGOR
Authors: Schmidt, W.; von der Lühe, O.; Volkmer, R.; Denker, C.;
   Solanki, S. K.; Balthasar, H.; Bello Gonzalez, N.; Berkefeld, Th.;
   Collados, M.; Fischer, A.; Halbgewachs, C.; Heidecke, F.; Hofmann,
   A.; Kneer, F.; Lagg, A.; Nicklas, H.; Popow, E.; Puschmann, K. G.;
   Schmidt, D.; Sigwarth, M.; Sobotka, M.; Soltau, D.; Staude, J.;
   Strassmeier, K. G.; Waldmann , T. A.
Bibcode: 2012AN....333..796S
Altcode:
  The 1.5 m telescope GREGOR opens a new window to the understanding
  of solar small-scale magnetism. The first light instrumentation
  includes the Gregor Fabry Pérot Interferometer (GFPI), a filter
  spectro-polarimeter for the visible wavelength range, the GRating
  Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The
  excellent performance of the first two instruments has already been
  demonstrated at the Vacuum Tower Telescope. GREGOR is Europe's largest
  solar telescope and number 3 in the world. Its all-reflective Gregory
  design provides a large wavelength coverage from the near UV up to at
  least 5 microns. The field of view has a diameter of 150 arcsec. GREGOR
  is equipped with a high-order adaptive optics system, with a subaperture
  size of 10 cm, and a deformable mirror with 256 actuators. The science
  goals are focused on, but not limited to, solar magnetism. GREGOR
  allows us to measure the emergence and disappearance of magnetic flux
  at the solar surface at spatial scales well below 100 km. Thanks to its
  spectro-polarimetric capabilities, GREGOR will measure the interaction
  between the plasma flows, different kinds of waves, and the magnetic
  field. This will foster our understanding of the processes that heat the
  chromosphere and the outer layers of the solar atmosphere. Observations
  of the surface magnetic field at very small spatial scales will shed
  light on the variability of the solar brightness.

Title: Wave Instabilities of a Collisionless Plasma in Fluid
    Approximation
Authors: Dzhalilov, N. S.; Kuznetsov, V. D.; Staude, Jürgen
Bibcode: 2011CoPP...51..621D
Altcode: 2009arXiv0911.2912D
  Wave properties and instabilities in a magnetized, anisotropic,
  collisionless, rarefied hot plasma in fluid approximation are studied,
  using the 16-moments set of the transport equations obtained from
  the Vlasov equations. These equations differ from the CGL-MHD fluid
  model (single fluid equations by Chew, Goldberger, and Low, 1956)
  by including two anisotropic heat flux evolution equations, where
  the fluxes invalidate the double polytropic CGL laws. We derived the
  general dispersion relation for linear compressible wave modes. Besides
  the classic incompressible fire hose modes there appear four types of
  compressible wave modes: two fast and slow mirror modes - strongly
  modified compared to the CGL model - and two thermal modes. In the
  presence of initial heat fluxes along the magnetic field the wave
  properties become different for the waves running forward and backward
  with respect to the magnetic field. The well known discrepancies between
  the results of the CGL-MHD fluid model and the kinetic theory are
  now removed: i) The mirror slow mode instability criterion is now the
  same as that in the kinetic theory. ii) Similarly, in kinetic studies
  there appear two kinds of fire hose instabilities - incompressible and
  compressible ones. These two instabilities can arise for the same plasma
  parameters, and the instability of the new compressible oblique fire
  hose modes can become dominant. The compressible fire hose instability
  is the result of the resonance coupling of three retrograde modes -
  two thermal modes and a fast mirror mode. The results can be applied
  to the theory of solar and stellar coronal and wind models.

Title: The Haus der Astronomie in Heidelberg-A New Center for
    Education and Outreach
Authors: Staude, J.
Bibcode: 2011ASPC..441..471S
Altcode:
  Since October 2009, a unique facility is being erected on the grounds
  of the Max Planck Institute for Astronomy on top of the Königstuhl
  Mountain above Heidelberg, in the immediate vicinity of the State
  Observatory. It will be dedicated to the communication between
  scientists, to the development of educational material for junior and
  high school students, to the training of teachers and student teachers
  in physics, astronomy and natural sciences, and to the information of
  the media and the general public about new developments and results
  in astronomical research. The building will be donated by the Klaus
  Tschira Foundation, while the Max Planck Society, the University and
  the City of Heidelberg, and the State Departments of Research and of
  Education will share the running costs of the new institution.

Title: Observational evidences for multi-component magnetic field
    structure in solar flares
Authors: Lozitsky, V. G.; Staude, J.
Bibcode: 2009JApA...29..387L
Altcode:
  No abstract at ADS

Title: Wave instabilities in an anisotropic magnetized space plasma
Authors: Dzhalilov, N. S.; Kuznetsov, V. D.; Staude, J.
Bibcode: 2008A&A...489..769D
Altcode: 2008arXiv0805.2405D
  Aims: We study wave instability in an collisionless, rarefied hot plasma
  (e.g. solar wind or corona). We consider the anisotropy produced by
  the magnetic field, when the thermal gas pressures across and along the
  field become unequal. <BR />Methods: We apply the 16-moment transport
  equations (obtained from the Boltzmann-Vlasov kinetic equation)
  including the anisotropic thermal fluxes. The general dispersion
  relation for the incompressible wave modes is derived. <BR />Results:
  It is shown that a new, more complex wave spectrum with stable and
  unstable behavior is possible, in contrast to the classic fire-hose
  modes obtained in terms of the 13-moment integrated equations.

Title: Instability of entropy waves in cosmic plasma
Authors: Somov, B. V.; Dzhalilov, N. S.; Staude, J.
Bibcode: 2008CosRe..46..392S
Altcode:
  A dispersion equation is derived for small disturbances of the
  magnetohydrodynamic type in optically transparent plasma with
  cosmic abundance of elements. The electron heat conductivity along
  the magnetic field and proton heat conductivity across the field
  are taken into account. It is shown that entropy waves increase
  exponentially in wide ranges of temperatures and densities of the
  cosmic plasma. Manifestations of instability of the entropy waves in
  the cosmic plasma are discussed.

Title: Comparison of Solar Magnetic Fields Measured at Different
Observatories: Peculiar Strength Ratio Distributions Across the Disk
Authors: Demidov, M. L.; Golubeva, E. M.; Balthasar, H.; Staude, J.;
   Grigoryev, V. M.
Bibcode: 2008SoPh..250..279D
Altcode: 2008SoPh..tmp..125D
  In this paper we analyze the distribution of magnetic strength ratios
  (MSR) across the solar disk using magnetograms in different spectral
  lines from the same observatory (Mount Wilson Observatory (MWO)
  and Sayan Observatory (SO)), magnetograms in the same line from
  different observatories (MWO, SO, Wilcox Solar Observatory (WSO)),
  and in different spectral lines from different observatories (the three
  observatories mentioned above, the National Solar Observatory/Kitt Peak
  (KP) and Michelson Doppler Imager (MDI) on board Solar and Heliospheric
  Observatory (SoHO)). We find peculiarities in some combinations of data
  sets. Besides the expected MSR center-to-limb variations, there is an
  equator-to-pole asymmetry, especially in the near-limb areas. Therefore,
  it is generally necessary to use 2D matrices of correction coefficients
  to reduce one kind of observation into another one.

Title: Magneto-Hydro-Dynamic Waves In The Collisionless Space Plasma
Authors: Dzhalilov, N. S.; Kuznetsov, V. D.; Staude, J.
Bibcode: 2007SunGe...2...65D
Altcode:
  The instability of magneto-hydro-dynamic (MHD) waves in an anisotropic,
  collisionless, rarefied hot plasma is studied. Anisotropy properties of
  such a plasma are caused by a strong magnetic field, when the thermal
  gas pressures across and along the field become unequal. Moreover,
  there appears an anisotropy of the thermal fluxes. The study of the
  anisotropy features of the plasma are motivated by observed solar
  coronal data. The 16 moments equations derived from the Boltzmann-Vlasov
  kinetic equation are used. These equations strongly differ from the
  usual isotropic MHD case. For linear disturbances the wave equations
  in homogenous anisotropic plasma are deduced. The general dispersion
  relation for the incompressible wave modes is derived, solved and
  analyzed. It is shown that a wide wave spectrum with stable and unstable
  behavior is possible, in contrast to the usual isotropic MHD case. The
  dependence of the instability on magnetic field, pressure anisotropy,
  and heat fluxes is investigated. The general instability condition
  is obtained. The results can be applied to the theory of solar and
  stellar coronal heating, to wind models and in other modeling, where
  the collisionless approximation is valid.

Title: GREGOR: the New German Solar Telescope
Authors: Balthasar, H.; von der Lühe, O.; Kneer, F.; Staude, J.;
   Volkmer, R.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
   C.; Heidecke, F.; Hofmann, A.; Klvaňa, M.; Nicklas, H.; Popow, E.;
   Puschmann, K.; Schmidt, W.; Sobotka, M.; Soltau, D.; Strassmeier,
   K.; Wittmann, A.
Bibcode: 2007ASPC..368..605B
Altcode: 2007arXiv0704.2693B
  GREGOR is a new open solar telescope with an aperture of 1.5 m. It
  replaces the former 45-cm Gregory Coudé telescope on the Canary island
  Tenerife. The optical concept is that of a double Gregory system. The
  main and the elliptical mirrors are made from a silicon-carbide material
  with high thermal conductivity. This is important to keep the mirrors
  on the ambient temperature avoiding local turbulence. GREGOR will be
  equipped with an adaptive optics system. The new telescope will be ready
  for operation in 2008. Post-focus instruments in the first stage will be
  a spectrograph for polarimetry in the near infrared and a 2-dimensional
  spectrometer based on Fabry-Pérot interferometers for the visible.

Title: Peculiarities of entropy and magnetosonic waves in optically
    thin cosmic plasma
Authors: Somov, B. V.; Dzhalilov, N. S.; Staude, J.
Bibcode: 2007AstL...33..309S
Altcode: 2007PAZh...33..352S
  The stability problem for small magnetohydrodynamic (MHD) perturbations
  in an optically thin, perfectly conducting uniform plasma with a
  cosmic abundance of elements is solved in the linear approximation. The
  electron heat conduction along the magnetic field and the proton heat
  conduction across the field are taken into account. We have shown
  for the first time that the entropy waves can grow exponentially,
  while the magnetosonic waves are damped in a wide range of physical
  conditions closest to the conditions in stellar coronae with the proper
  allowance for radiative losses. Slow magnetosonic waves are damped
  particularly rapidly. For the solar corona, the calculated damping
  decrement of slow magnetosonic waves agrees well with the averaged
  one in 11 quasi-periodic events observed from the TRACE satellite in
  extreme ultraviolet radiation. Other possible astrophysical applications
  of the results obtained are briefly discussed.

Title: The Characteristic Length Scale of the Magnetic Fluctuation in
a Sunspot Penumbra: A Stochastic Polarized Radiative Transfer Approach
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2007astro.ph..3327C
Altcode:
  The characteristic size of penumbral structures are still below the
  current resolution limit of modern solar telescopes. Though we have
  seen a significant progress in theoretical work over the last decades
  no tight constraints can be placed on the size of penumbral structures
  in order to favor models with relatively large and thick magnetic
  flux elements, just at or below the current resolution limit, or on
  the other hand, clusters of optically thin micro-structures. Based on
  a macroscopic 2-component inversion and the approach of polarized
  radiative transfer in stochastic media, we have estimated the
  characteristic length scale of the magnetic fluctuation in a sunspot
  penumbra from observed Stokes spectra. The results yield a coherent
  picture for the entire magnetic neutral line of the penumbra and
  indicate that the magnetic fluctuations have a typical length scale
  between 30 km and 70 km.

Title: New high resolution solar telescope GREGOR
Authors: Volkmer, R.; von der Lühe, O.; Kneer, F.; Staude, J.;
   Balthasar, H.; Berkefeld, T.; Caligari, P.; Collados, M.; Halbgewachs,
   C.; Heidecke, F.; Hofmann, A.; Klvaña, M.; Sobotka, M.; Nicklas, H.;
   Popow, E.; Puschmann, K. G.; Schmidt, W.; Soltau, D.; Strassmeier,
   K.; Wittmann, A. D.
Bibcode: 2007msfa.conf...39V
Altcode:
  The 1.5m solar telescope GREGOR is being constructed at Tenerife,
  Spain. Its purpose is to observe with high spatial and spectral
  resolution small-scale dynamic magnetic features on the Sun. The
  telescope is completely open with retractable dome and actively cooled
  primary mirror made of silicon carbide to minimize thermal effects
  on the image quality. After completion it will be one of the most
  powerful solar telescopes. This paper presents a general overview of
  the telescope characteristics and the current status.

Title: The Characteristic Length Scale of the Magnetic Fluctuation in
a Sunspot Penumbra: A Stochastic Polarized Radiative Transfer Approach
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2006ASPC..358..137C
Altcode:
  The characteristic size of penumbral structures are still below
  the current resolution limit of modern solar telescopes. Though we
  have seen a significant progress in theoretical work over the last
  decades no tight constraints can be placed on the size of penumbral
  structures in order to favor models with relatively large and thick
  magnetic flux elements, just at or below the current resolution limit,
  or on the other hand, clusters of optically thin micro-structures. <P
  />Based on a macroscopic 2-component inversion and the approach of
  polarized radiative transfer in stochastic media, we have estimated the
  characteristic length scale of the magnetic fluctuation in a sunspot
  penumbra from observed Stokes spectra. The results yield a coherent
  picture for the entire magnetic neutral line of the penumbra and
  indicate that the magnetic fluctuations have a typical length scale
  between 30 km and 70 km.

Title: The new 1.5m solar telescope GREGOR: first light and start
    of commissioning
Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude,
   Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens;
   Heidecke, Frank; Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald;
   Wittmann, Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus;
   Sobotka, Michal; Klvana, Miroslav; Collados, Manuel
Bibcode: 2006SPIE.6267E..0WV
Altcode: 2006SPIE.6267E..29V
  The integration of the three main silicon carbide mirrors into the new
  1.5 m solar telescope GREGOR at Izana on Tenerife, Spain is planned
  during 2006. We expect first light at the end of 2006. A progress
  report about integration of the optics and mechanics and planning of
  the commissioning phase of the telescope and post focus instruments
  will be presented at the meeting. The GREGOR telescope is build by a
  consortium of the Kiepenheuer Institut fur Sonnenphysik in Freiburg,
  the Astrophysikalische Institut Potsdam, the Institut fur Astronomie
  Gottingen and additional national and international Partners.

Title: Line Formation in Inhomogeneous Atmospheres and the Magnetic
    Structure of the Internetwork
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2005ESASP.596E...9C
Altcode: 2005ccmf.confE...9C
  No abstract at ADS

Title: The new 1.5 solar telescope GREGOR: progress report and
    results of performance tests
Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude,
   Jürgen; Berkefeld, Thomas; Caligari, Peter; Halbgewachs, Clemens;
   Schmidt, Wolfgang; Soltau, Dirk; Nicklas, Harald; Wittmann, Axel;
   Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka, Michal;
   Klvana, Miroslav; Collados, Manuel
Bibcode: 2005SPIE.5901...75V
Altcode:
  The telescope structure including control system and the complete
  retractable dome of the new 1.5 m solar telescope GREGOR were
  assembled during 2004 at Izana on Tenerife, Spain. The GREGOR
  telescope is build by a consortium of the Kiepenheuer Institut fuer
  Sonnenphysik, the Astrophysikalische Institut Potsdam, the Institut
  fuer Astrophysik Goettingen and additional national and international
  Partners. Pointing, tracking and thermal tests were made to verify
  the proposed performance. The results of these tests and a progress
  report of the project will be presented.

Title: Dynamics of solar active regions. II. Oscillations observed
    with MDI and their relation to the magnetic field topology
Authors: Muglach, K.; Hofmann, A.; Staude, J.
Bibcode: 2005A&A...437.1055M
Altcode:
  We present new results of an international joint observing campaign,
  which was carried out in September 2000 to study the oscillatory
  behaviour of solar active regions. We concentrate on oscillations
  in the lower layers of the solar atmosphere as observed with the
  Michelson Doppler Imager (MDI, Scherrer et al. 1995, Sol. Phys., 162,
  129). The resulting photospheric oscillation power maps are compared
  with chromospheric maps from simultaneous UV continuum data (taken with
  the TRACE instrument). From a magnetic field extrapolation of the MDI
  magnetograms we infer that the reduction in chromospheric high frequency
  power and enhancement of photospheric high frequency power may be
  explained by the interaction of acoustic waves with the magnetic canopy.

Title: Active Region Oscillations and Their Relation to the Magnetic
    Field Topology
Authors: Muglach, K.; Hofmann, A.; Staude, J.
Bibcode: 2005AGUSMSH13C..03M
Altcode:
  In this contribution we present an analysis of time sequences of MDI
  intensity and Doppler velocity together with simultaneous filtergrams
  taken by TRACE at 1700A in an active region. The high frequency
  halos found in MDI velocity and the deficiency of high frequency
  power sampled at the height of the TRACE UV filter around the active
  region can be explained by an interaction of the acoustic wave field
  with the magnetic field of the active region. From a magnetic field
  extrapolation we calculate the plasma β for the complete TRACE FOV
  up to the base of the corona. The contours giving the location of β
  approximately 1 where h=500 km agree very well with the decrease in
  1700A high frequency power.

Title: Line formation in turbulent magnetic atmospheres
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2005AN....326..296C
Altcode:
  We present a stochastic formulation of the polarized radiative transfer
  in an atmosphere permeated by a random magnetic field. On the basis
  of a Markov process we describe the line formation as a stochastic
  process which allows us to account for a finite correlation length of
  the fluctuating structures. The resulting stochastic master equation
  describes the evolution of the expectation value of the Stokes vector
  (the macroscopic observable) through the atmosphere. As the correlation
  length (mean structural length scale of the fluctuating or turbulent
  elements) appears explicitly in the stochastic transport equation it
  can be used as a diagnostic parameter from which an estimation of the
  underlying structural length scale is possible.

Title: The Helioseismological CORONAS-F DIFOS Experiment
Authors: Lebedev, N. I.; Kuznetsov, V. D.; Oraevskii, V. N.; Staude,
   J.; Kostyk, R. I.
Bibcode: 2004ARep...48..871L
Altcode:
  The CORONAS-F DIFOS experiment continues the CORONAS-I studies
  started in 1994, devoted to investigations of solar global
  oscillations. CORONAS-F was launched July 31, 2001. Variations in
  the intensity of the solar radiation are measured in the six spectral
  intervals of the multi-channel photometer: 350, 500, 650, 850, 1100,
  and 1500 nm, with the bandwidths being about 10% of the central
  wavelength of each interval. The scientific goals of the experiment,
  a brief description of the instrument, and observational conditions
  are presented, as well as the data processing techniques. The first
  observations of the low-order p eigenmodes of the solar oscillations
  are presented for various wavelength ranges. A decrease in the relative
  amplitudes with observing wavelength is indicated. The amplitude ratios
  for various spectral ranges agree well with those detected earlier in
  ground-and space-based experiments.

Title: Progress report of the 1.5 m solar telescope GREGOR
Authors: Volkmer, Reiner; von der Lühe, Oskar F.; Kneer, Franz;
   Staude, Jürgen; Berkefeld, Thomas; Caligari, Peter; Schmidt,
   Wolfgang; Soltau, Dirk; Nicklas, Harald; Wiehr, Eberhardt; Wittmann,
   Axel; Balthasar, Horst; Hofmann, Axel; Strassmeier, Klaus; Sobotka,
   Michal; Klvana, Miroslav; Collados, Manuel
Bibcode: 2004SPIE.5489..693V
Altcode:
  GREGOR is the new 1.5 m solar telescope assembled on Tenerife, Spain, by
  the German consortium of the Kiepenheuer Institut fur Sonnenphysik, the
  Astronomischen Institut Potsdam, the Universitats-Sternwarte Gottingen
  and other national and international Partners. The refurbishment of
  the building is almost finished. The manufacturing of the telescope
  structure and the optics is still in progress. After the integration of
  the new complete retractable dome in July 2004 the telescope structure,
  optic and post focus instruments will be assembled during the rest of
  the year. First light is planned during May 2005.

Title: Eigenoscillations of the differentially rotating
    Sun. II. Generalization of the Laplace tidal equation
Authors: Dzhalilov, N. S.; Staude, J.
Bibcode: 2004A&A...421..305D
Altcode: 2002astro.ph..1170D
  The general partial differential equation governing linear adiabatic
  nonradial oscillations in a spherical, differentially and slowly
  rotating non-magnetic star is derived. This equation describes
  mainly low-frequency and high-degree g-modes, convective g-modes,
  rotational Rossby-like vorticity modes, and their mutual interaction
  for arbitrarily given radial and latitudinal gradients of the rotation
  rate. Applying to this equation the ``traditional approximation'' of
  geophysics results in a separation into radial- and angular-dependent
  parts of the physical variables, each of which is described by an
  ordinary differential equation. The angular parts of the eigenfunctions
  are described by the Laplace tidal equation generalized here to
  take into account differential rotation. It is shown that there
  appears a critical latitude in the sphere where the frequencies of
  eigenmodes coincide with the frequencies of inertial modes. The resonant
  transformation of the modes into the inertial waves acts as a resonant
  damping mechanism of the modes. Physically this mechanism is akin to
  the Alfvén resonance damping mechanism for MHD waves. It applies even
  if the rotation is rigid. The exact solutions of the Laplace equation
  for low frequencies and rigid rotation are obtained. The eigenfunctions
  are expressed by Jacobi polynomials which are polynomials of higher
  order than the Legendre polynomials for spherical harmonics. In this
  ideal case there exists only a retrograde wave spectrum. The modes are
  subdivided into two branches: fast and slow modes. The long fast waves
  carry energy opposite to the rotation direction, while the shorter
  slow-mode group velocity is in the azimuthal plane along the direction
  of rotation. It is shown that the slow modes are concentrated around the
  equator, while the fast modes are concentrated around the poles. The
  band of latitude where the mode energy is concentrated is narrow, and
  the spatial location of these band depends on the wave numbers (l, m).

Title: Observations of oscillations in the transition region   above
    sunspots
Authors: Rendtel, J.; Staude, J.; Curdt, W.
Bibcode: 2003A&A...410..315R
Altcode:
  Observations during two campaigns of the SUMER spectrograph and the EIT
  imager onboard SoHO were used to analyse oscillations in bright sunspot
  plumes. We report variations of both intensity and velocity seen in
  EUV emission lines originating in the sunspot upper chromosphere and
  the transition region. The wavelet analysis reveals rapidly changing
  conditions in the emitting volumes. Generally, oscillations in the 5
  min range dominate in the chromosphere, while the transition region
  lines show oscillations at shorter periods (2 to 3 min). A drift of the
  oscillation period of the Doppler velocity from 5 min to 2.5 min within
  about 30 min can be explained by a strongly non-stationary behaviour
  of the upper chromosphere and transition region, probably related
  to downstream of material within the plume region. Synchronous EIT
  observations of the lower corona show no intensity oscillations. This
  hints either at a strong damping or a downward reflection in the upper
  transition region or lower corona.

Title: Current Status of the 1.5m Solar Telescope GREGOR
Authors: Volkmer, Reiner; von der Lühe, Oskar; Kneer, Franz; Staude,
   Jürgen; Berkfeld, Thomas; Schmidt, Wolfgang; Soltau, Dirk; Nicklas,
   Harald; Wiehr, Eberhardt; Wittman, Axel; Hofmann, Axel; Sobotka,
   Michal; Klvana, Miroslav
Bibcode: 2003ANS...324..112V
Altcode: 2003ANS...324..P19V
  No abstract at ADS

Title: GREGOR: the new 1.5m solar telescope on Tenerife
Authors: Volkmer, Reiner; von der Luehe, Oskar; Kneer, Franz; Staude,
   Juergen; Hofmann, Axel; Schmidt, Wolfgang; Sobotka, Michal; Soltau,
   Dirk; Wiehr, Eberhardt; Wittmann, Axel; Berkefeld, Thomas
Bibcode: 2003SPIE.4853..360V
Altcode:
  The new 1.5 m high resolution telescope will be build up on the reused
  solar tower of the German 45 cm Gregory Coudé Telescope at the Teide
  Observatory, Izaña, Tenerife. The new telescope is a Gregory type
  with open telescope structure, alt-azimuth mount, complete retractable
  dome, and a pool of well established and new developed post focus
  instruments. An adaptive optics system provides the capability for
  diffraction limited observations at visible wavelengths and the
  polarimetry device in the secondary focus reduces the perturbation
  due to instrumental polarization in an efficient way. We describe the
  main optical characteristics and the focal plane instrumentation with
  respect to the latest status of the project.

Title: Oscillations of velocity and magnetic fields in sunspot umbrae
Authors: Staude, J.
Bibcode: 2003AN....324..391S
Altcode:
  No abstract at ADS

Title: Diagnostics of Magnetic Field Mesostructuring
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2003ASPC..307..125C
Altcode:
  No abstract at ADS

Title: Meso-structured magnetic atmospheres: Stochastic polarized
    radiative transfer and Stokes profile inversion
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2003AN....324..392C
Altcode:
  No abstract at ADS

Title: Multi-Component Magnetic Field Structure in Solar Flares
Authors: Lozitsky, V. G.; Staude, J.
Bibcode: 2003ASPC..307..378L
Altcode:
  No abstract at ADS

Title: GREGOR, a 1.5 m Gregory-type telescope for solar observation
Authors: Kneer, F.; Hofmann, A.; von der Lühe, O.; Soltau, W. Schmidt
   D.; Staude, J.; Wiehr, E.; Wittmann, A. D.
Bibcode: 2002NCimC..25..689K
Altcode:
  No abstract at ADS

Title: Signature of differential rotation in solar disk-integrated
    chromospheric line emission
Authors: Hasler, K. -H.; Rüdiger, G.; Staude, J.
Bibcode: 2002AN....323..123H
Altcode:
  UARS SOLSTICE data have been subjected to Fourier and wavelet analyses
  in order to search for the signature of the solar rotation law in
  the disk-integrated irradiance of UV lines. Lyman-alpha, Mg II, and
  Ca II data show a different behaviour. In the SOLSTICE data there
  are significant temporal variations of the rotation rate of the UV
  tracers over 5 - 6 years. Often several distinct rotation periods
  appear almost simultaneously. Beside the basic period around 27 days
  there are signals at 32 - 35 days corresponding to the rotation rate
  at very high latitudes. For more than 5 years during another period of
  the solar cycle the rotational behaviour is quite different; there is
  an indication of differential rotation of active regions in these Ca
  II ground-based data. The data contain a wealth of information about
  the solar differential rotation, but it proves difficult to disentangle
  the effects of the different emitting sources.

Title: Magnetic field oscillations of sunspots?
Authors: Staude, J.
Bibcode: 2002AN....323..317S
Altcode:
  For 3 decades it is known that sunspots show oscillations of velocity
  and intensity, that is of thermodynamic quantities. Oscillatory power
  is concentrated at periods around 2 \ldots 3 min, 5 min, and ga 20
  min. Attempts to measure related magnetic field oscillations were
  contradictory. Now there are hints of significant magnetic signals
  in 2-D spectro-polarimetric data with power mainly in pores and at
  the boundary between the umbra and the penumbra of larger spots. We
  discuss these data and possibilities of their interpretation which
  are still a matter of debate. The magnetic oscillations could be the
  signature of a `whispering gallery' like mode of slow body waves in
  a thick magnetic flux-tube. However, other interpretations such as
  opacity oscillations or a crosstalk from velocity or compressive waves
  cannot be ruled out as long as better observed data, measurements of
  phase shifts in particular, and more realistic models are still missing.

Title: On nonadiabatic waves in the photospheres of cool stars
Authors: Pregla, A. V.; Zhugzhda, Y. D.; Staude, J.
Bibcode: 2002AN....323..465P
Altcode:
  The coupled set of equations of hydrodynamics and radiative transfer
  is derived for small disturbances in a plane, grey atmosphere. Only
  radiative transfer is taken into account in the energy equation;
  dynamical effects of radiation are ignored. A mean stationary radiative
  flux through the photosphere is taken into account. The radiative
  transfer equation is used by assuming the Eddington approximation,
  moreover, an exponential height profile of the temperature and an
  analytical opacity formula are supposed. For this model we obtained an
  asymptotic solution for plane nonadiabatic acoustic waves and radiation
  waves. The approach provides a detailed discussion of the interaction
  of nonadiabatic p-modes and radiation waves in a realistic model of
  the photosphere of a solar-like star.

Title: Long-period eigenoscillations of the solar interior: 1-3 yr,
    20-40 yr, and 1500-20000 year modes
Authors: Staude, Jürgen; Dzhalilov, Namig S.
Bibcode: 2002ESASP.477..167S
Altcode: 2002scsw.conf..167S
  Waves with periods much larger than the rotation period become trapped
  in the solar radiative interior. The modelling considers compressible,
  nonadiabatic, Rossby- like modes (ɛ-mechanism and radiative losses are
  taken into account) for a very small latitudinal gradient of rotation,
  without an arbitrary choice of other free parameters. We found global
  vorticity modes in 3 separate period ranges of ≍1-3 yr, 20-40 yr,
  and 1500-20000 yr which are maximum unstable. The discovered resonant
  cavity modes (called R-modes) are different from the known r-modes. We
  discuss some prospects to develop the theory of R-modes as a driver
  of the dynamics in the convective zone which could explain e.g.,
  observed short-term fluctuations of rotation, a control of the solar
  magnetic cycle, and abrupt changes of terrestrial climate in the past
  (Dansgaard-Oeschger events).

Title: Eigenoscillations of the differentially rotating
    Sun. I. 22-year, 4000-year, and quasi-biennial modes
Authors: Dzhalilov, N. S.; Staude, J.; Oraevsky, V. N.
Bibcode: 2002A&A...384..282D
Altcode: 2002astro.ph..1120D
  Retrograde waves with frequencies much lower than the rotation frequency
  become trapped in the solar radiative interior. The eigenfunctions of
  the compressible, nonadiabatic (epsilon -mechanism and radiative losses
  taken into account) Rossby-like modes are obtained by an asymptotic
  method assuming a very small latitudinal gradient of the rotation
  rate. An integral dispersion relation for the complex eigenfrequencies
  is derived as a solution of the boundary value problem. The discovered
  resonant cavity modes (called R-modes) are fundamentally different
  from the known r-modes: their frequencies are functions of the solar
  interior structure, and the reason for their existence is not related
  to geometrical effects. The most unstable R-modes are those with
  periods of ~1-3 yr, 18-30 yr, and 1500-20 000 yr; these three separate
  period ranges are known from solar and geophysical data. The growing
  times of those modes which are unstable with respect to the epsilon
  -mechanism are ~10<SUP>2</SUP>, 10<SUP>3</SUP>, and 10<SUP>5</SUP>
  years, respectively. The amplitudes of the R-modes are growing towards
  the center of the Sun. We discuss some prospects to develop the theory
  of R-modes as a driver of the dynamics in the convective zone which
  could explain, e.g., observed short-term fluctuations of rotation, a
  control of the solar magnetic cycle, and abrupt changes of terrestrial
  climate in the past.

Title: Global Oscillations of the Sun in a Wide Optical Spectral
Range: DIFOS Experiment Onboard CORONAS-F
Authors: Oraevsky, V.; Lebedev, N.; Kuznetsov, V.; Staude, J.;
   Kostyk, R.
Bibcode: 2002cosp...34E.345O
Altcode: 2002cosp.meetE.345O
  The DIFOS experiment onboard the CORONAS-F spacecraft continues the
  investigation of solar global oscillations, which was started in 1994
  during the CORONAS-I mission. The satellite was launched on July
  31, 2001. It uses a multi-channel photometer to observe irradiance
  fluctuations. The photometer measures fluctuations of the solar
  flux in six optical spectral ranges: near 350, 500, 650, 850, 1100,
  and 1500 nm with a bandwidth of about 10% of the central wavelength
  for each. After a short description of the instrumentation and data
  analyses, we present results of observations of low-degree p-modes of
  global oscillations for different observational optical ranges. The
  oscillation amplitudes were found to decrease with the growth of the
  wavelength. The amplitude ratios for different wavelength are in a
  good agreement with earlier observations and theoretical predictions.

Title: GREGOR: a 1.5 m telescope for solar research
Authors: von der Lühe, O.; Schmidt, W.; Soltau, D.; Berkefeld, Th.;
   Kneer, F.; Staude, J.
Bibcode: 2001AN....322..353V
Altcode:
  GREGOR will be a new 1.5 meter solar telescope at the Teide Observatory,
  Izaña, Tenerife. It will provide observations with high polarimetric
  precision at visible and infra-red wavelengths from Earth in the
  solar photosphere and chromosphere with a resolution of 70 km on the
  Sun. GREGOR replaces the 45 cm Gregory Coudé telescope.

Title: Introduction to Volume 322 (5/6) Proceedings of the
    Joint-Discussion #1 and the Mini-Symposia #9 and #10 at the Joint
    European and National Astronomical Meeting (JENAM) for 2001
Authors: Strassmeier, K. G.; Staude, J.; Dreizler, S.
Bibcode: 2001AN....322..271S
Altcode:
  This volume of AN contains the proceedings of the Joint Discussion
  #1 (JD-1) ``Astronomy with Robotic Telescopes: Present and Future
  Projects'' and of the Mini Symposia #9 (MS-9) ``Hot subdwarfs,
  white dwarfs, and low-mass star evolution'', and #10 (MS-10) ``Large
  Telescopes for Solar Physics''. The meetings were held as part of the
  JENAM 2001 conference ``Five Days of Creation. Astronomy with Large
  Telescopes from Ground and Space'' in Munich, Germany, from September
  10 through 15, 2001.

Title: Post-focus instrumentation for GREGOR
Authors: Kneer, F.; Hofmann, A.; von der Lühe, O.; Schmidt, W.;
   Soltau, D.; Staude, J.; Wiehr, E.; Wittmann, A. D.
Bibcode: 2001AN....322..361K
Altcode:
  GREGOR is a high-resolution solar telescope with an aperture of 1.5
  m. It will be equipped with an Adaptive Optics system and is designed
  for high-precision measurements of magnetic fields and plasma motions
  in the solar photosphere and chromosphere with a resolution of 70
  km on the Sun. GREGOR will replace the Gregory Coudé Telescope at
  the Observatorio del Teide on Tenerife. In concert with the other
  solar telescopes at Teide Observatory it will be useful for studying
  the dynamics of the solar atmosphere and the underlying physical
  processes. GREGOR will also serve as a test bed for next generation
  solar telescopes. We discuss briefly the postfocus instrumentation
  of GREGOR.

Title: The inversion of Stokes profiles with artificial neural
    networks
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2001A&A...378..316C
Altcode:
  We investigate the application of artificial neural networks (ANNs)
  for the interpretation of Stokes profiles. We have employed ANNs to
  approximate the nonlinear inverse mapping between the Stokes profiles
  and some of the underlying atmospheric parameters. This approximate
  model is used in the following to carry out a fast non-iterative
  inversion of synthetic Stokes profiles. We have used synthetic Stokes
  profiles of the photospheric infrared line Fe I lambda 15648 to
  demonstrate that the ANNs are capable to yield accurate single valued
  estimates of the complete magnetic field vector, line-of-sight (LOS)
  velocity, microturbulence, macroturbulence and the filling factor with
  exceptional speed. For a stratified atmosphere we also demonstrate
  that these single valued parameters do represent very good averaged
  values of the input stratification. To retrieve some of the temperature
  information encoded in the Stokes profiles we modeled a neural network
  classifier on the basis of several semi-empirical model atmospheres
  (i.e. temperature and pressure stratification). With this classifier
  we are able to determine the probability that a given Stokes profile
  has its origin from a particular temperature stratification of a
  semi-empirical model.

Title: GREGOR: high resolution solar observations from 1 AU
Authors: von der Lühe, O.; Schmidt, W.; Soltau, D.; Kneer, F.;
   Staude, J.; Pailer, N.
Bibcode: 2001ESASP.493..417V
Altcode: 2001sefs.work..417V
  No abstract at ADS

Title: Waves in Sunspots: Resonant Transmission and the Adiabatic
    Coefficient
Authors: Settele, A.; Staude, J.; Zhugzhda, Y. D.
Bibcode: 2001SoPh..202..281S
Altcode:
  We investigate linear acoustic-gravity waves in three different
  semi-empirical model atmospheres of large sunspot umbrae. The sunspot
  filter theory is applied, that is, the resonant transmission of
  vertically propagating waves is modelled. The results are compared
  with observed linear sunspot oscillations. For three umbral models we
  present the transmission coefficients and the energy density of the
  oscillations with the maxima of transmission. The height dependence of
  the adiabatic coefficient (the ratio of specific heats) γ strongly
  influences the calculated resonance frequencies. The variable γ can
  explain the observed closely spaced resonance period peaks. The first
  resonance in the 3 min range is interpreted as a resonance of the upper
  chromosphere only, while the higher order peaks are resonances of the
  whole chromosphere.

Title: Observations of oscillations above sunspots
Authors: Rendtel, Jürgen; Staude, Jürgen
Bibcode: 2001ESASP.493..337R
Altcode: 2001sefs.work..337R
  No abstract at ADS

Title: Analysis and interpretation of Stokes profiles with artificial
    neural networks
Authors: Carroll, T. A.; Staude, J.
Bibcode: 2001ESASP.493..183C
Altcode: 2001sefs.work..183C
  No abstract at ADS

Title: Shifts of p-mode frequencies by wave tunneling through the
    solar atmosphere
Authors: Dzhalilov, Namig S.; Staude, Jürgen
Bibcode: 2001ESASP.464..625D
Altcode: 2001soho...10..625D
  Global adiabatic p-modes are modelled by an asymptotic theory, taking
  into account the influence of the solar atmosphere on the formation of
  the eigenoscillations: waves of the whole frequency range 2-10 mHz are
  now reaching the chromosphere-corona transition region (CCTR) by the
  tunneling of acoustic waves through the atmospheric barriers. The main
  acoustic cavity inside the Sun becomes considerably extended in this
  way, leading to a change of frequencies: low frequencies are increased,
  while high frequencies are decreased. The transition from low p-mode
  frequencies to high peak frequencies &gt;6mHz is smooth. The imaginary
  parts of the frequencies indicate a decay of the amplitudes, resulting
  from considerable energy losses by tunneling from the main cavity. A
  penetration of linear p-modes to the corona is impossible. The behavior
  of the CCTR is that of a free surface: the p-modes may drive forced
  surface gravity waves of this free surface.

Title: Problems in the interpretation of sunspot oscillation
    measurements
Authors: Settele, A.; Staude, J.; Zhugzhda, Y. D.
Bibcode: 2001ESASP.464..247S
Altcode: 2001soho...10..247S
  Sunspot oscillations are observed in spectral lines formed at different
  depths in the sunspot atmosphere. The interpretation of measurements in
  chromospheric lines is problematic as the lines are formed in NLTE. So
  the measured power spectra do not originate from one specific depth in
  the atmosphere but are smoothed out over a larger region. This will also
  influence the phase shifts of the waves measured in different spectral
  lines and might cause some misinterpretation. These complications
  are illustrated by our model calculations: Modelling the transmission
  of magneto-atmospheric waves through the sunspot atmosphere by means
  of the sunspot filter approach, we show the "real" power spectra at
  different atmospheric depths. These results are compared with Ca II-H/K
  power spectra gained from the NLTE calculations of the Ca II-H/K lines
  in an atmosphere perturbed by our waves. All results are preliminary.

Title: GREGOR, a 1.5 m Gregory-type Telescope for Solar Observation
Authors: Kneer, F.; Hofmann, A.; von der Lühe, O.; Schmidt, W.;
   Soltau, D.; Staude, J.; Wiehr, E.; Wittmann, A. D.
Bibcode: 2001AGM....18.P223K
Altcode:
  GREGOR is a high-resolution solar telescope with an aperture of 1.5
  m. It will be equipped with an Adaptive Optics system and is designed
  for high-precision measurements of magnetic fields and plasma motions
  in the solar atmosphere and chromosphere with a resolution of 70 km
  on the Sun. GREGOR will replace the Gregory Coudé Teleskope at the
  Observatorio del Teide on Tenerife. We describe the optical design
  and the focal plane instrumentation. In concert with the other solar
  telescopes at Teide Observatory it will be useful for studying the
  dynamics of the solar atmosphere and the underlying processes. GREGOR
  will also serve as a test bed for next generation solar telescopes.

Title: Sunspot transition region oscillations
Authors: Rendtel, J.; Staude, J.; Wilhelm, K.; Gurman, J. P.
Bibcode: 2001ESASP.464..235R
Altcode: 2001soho...10..235R
  Intensity and velocity oscillations have been observed over a period
  of 4.3 hours in lines of Ne VIII and C IV with the SUMER spectrograph
  aboard SOHO. These lines are formed in the EUV plume above a
  sunspot. Applying a wavelet analysis, we find oscillations mainly close
  to 3 mHz. The temporal behaviour is strongly intermittent, particularly
  for the velocity oscillations. This non-stationary behaviour may be
  related with occurrence of blinkers in the umbral transition region.

Title: Resonant Transmission of Magneto-atmospheric Waves in Sunspot
    Umbrae
Authors: Staude, J.; Rendtel, J.; Settele, A.
Bibcode: 2001IAUS..203..320S
Altcode:
  Oscillations of velocity and intensity, of the magnetic field in
  the photosphere as well, have been observed at all height levels of
  the atmosphere above sunspots from the photosphere up to the lower
  corona. We discuss the nonstationary behavior of intensity and velocity
  oscillations; they have been observed by SOHO in transition region lines
  formed in the EUV plume of a sunspot during a continuous time series
  of 4.3 hours. Applying a wavelet analysis, we find periods around 3 mHz
  with different periods in the observed EUV lines. Moreover, we discuss
  the observed oscillations within the frame of model calculations
  for the resonant transmission of magneto-atmospheric waves through
  realistic models of the sunspot subphotosphere and atmosphere.

Title: Long-period Eigenoscillations of the Solar Interior: 22-year,
    4500-year, and Quasi-biennial Modes
Authors: Staude, J.; Dzhalilov, N. S.
Bibcode: 2001AGM....18..P04S
Altcode:
  Waves with periods much larger than the rotation period become trapped
  in the solar radiative interior. Our modelling considers compressible,
  nonadiabatic, Rossby-like modes (ɛ-mechanism and radiative losses are
  taken into account) for a very small latitudinal gradient of rotation,
  without an arbitrary choice of further free parameters. These `R-modes'
  are fundamentally different from the known `r-modes': their frequencies
  are functions of the solar interior structure, and the reason for
  their existence is not related to geometrical effects. The amplitudes
  of the R-modes are growing towards the center of the Sun. We found
  global vorticity modes in 3 separate period ranges around 1.3-2.0,
  22, and 4500 years (with an onset at 1500 years) which are maximum
  unstable. They could possibly control the solar activity cycle, cause
  the 1.3 year period variation of solar rotation which was recently
  found in the deeper convective zone and produce the quasi-biennial
  oscillations in solar activity and geophysical data. Moreover, they
  could be related to the abrupt changes of terrestrial climate in the
  past (Dansgaard-Oeschger events).

Title: Low-Frequency Eigenoscillations of the Differentially Rotating
    Solar Interior
Authors: Dzhalilov, N. S.; Staude, J.
Bibcode: 2001ASPC..248..173D
Altcode: 2001mfah.conf..173D
  No abstract at ADS

Title: Influence of the solar atmosphere on the p-mode
    eigenoscillations
Authors: Dzhalilov, N. S.; Staude, J.; Arlt, K.
Bibcode: 2000A&A...361.1127D
Altcode:
  An asymptotic theory of global adiabatic p-modes is developed,
  taking into account the influence of the solar atmosphere. It is
  shown that waves of the whole frequency range nu ~ 2-10 mHz may
  reach the chromosphere-corona transition region (CCTR) by means of
  a tunneling through the atmospheric barriers. The primary acoustic
  cavity inside the Sun becomes considerably extended by this way,
  leading to a change of frequencies: low frequencies are increased,
  while high frequencies are decreased. The transition from low p-mode
  frequencies to high peak frequencies (nu &gt;~ 6;mHz) is smooth. The
  locations of the turning points are determined from the wave equation
  for {div}*/rightarrow{v}. It is shown that the internal turning point
  of the acoustic cavity is strongly shifted toward the center of the Sun,
  while the upper turning point is shifted from the surface to CCTR. That
  means, the turning points cannot be located in the convective zone. A
  new complex integral dispersion relation for the eigenfrequencies is
  derived. The imaginary parts of the frequencies indicate a decay of
  the amplitudes, resulting from considerable energy losses by tunneling
  from the main cavity. It is shown that waves with a decaying amplitude
  (complex frequency) may exist in a limited area only, penetration of
  linear p-modes to the corona is impossible. The CCTR acts as a free
  surface. We conclude that the p-modes may drive forced surface gravity
  waves at this surface.

Title: Multi-mode oscillations of sunspots
Authors: Zhugzhda, Y. D.; Balthasar, H.; Staude, J.
Bibcode: 2000A&A...355..347Z
Altcode:
  Oscillations of the magnetic field in the sunspot photosphere have been
  detected by recent high-resolution, two-dimensional observations. Their
  power is concentrated in isolated small flux bundles (pores) outside of
  larger umbrae and at the boundary between umbra and penumbra of larger
  spots. The slow body mode provides an explanation of the appearance
  of magnetic oscillations in small sunspots if the azimuth number m=0,
  but also of the small features piling up in rings in large sunspots. In
  the latter model the magnetic oscillations are the signature of the
  slow body mode with m&gt;&gt; 1, which bears a resemblance to the
  well-known whispering gallery mode in acoustics. The slow surface
  modes and fast body modes are also discussed.

Title: Helioseismologie - ein neues Fenster der Sonnenforschung.
Authors: Staude, J.
Bibcode: 2000A&R....37....4S
Altcode:
  No abstract at ADS

Title: Friedrich Wilhelm Jäger (1914 - 14. Februar 2000).
Authors: Staude, J.
Bibcode: 2000MitAG..83...13S
Altcode:
  No abstract at ADS

Title: Sonnenphysik in Potsdam Title: Sonnenphysik in Potsdam Title:
    Solar physics in Potsdam.
Authors: Staude, Jürgen
Bibcode: 2000AcHA...11...81S
Altcode:
  Solar research initiated the establishment of the Astrophysical
  Observatory Potsdam (AOP) in 1874. The present contribution outlines the
  development of solar physics in Potsdam from the early history of the
  AOP to this day. The main topics are the work of Karl Schwarzschild,
  the investigations related to the general theory of relativity, the
  foundation of the Einstein tower, Walter Grotrian's founding of modern
  coronal physics, and the investigations of sunspot magnetic fields.

Title: Sonnenforschung in Potsdam - Streiflichter aus der Geschichte
Title: Sonnenforschung in Potsdam - Streiflichter aus der Geschichte
Title: Solar research in Potsdam - sidelights on its history.
Authors: Staude, Jürgen; Hofmann, Axel
Bibcode: 2000AcHA....8..107S
Altcode:
  No abstract at ADS

Title: GREGOR: A 1.5m Telescope for Solar Research
Authors: von der Lühe, O.; Schmidt, Wolfgang; Soltau, Dirk; Kneer,
   Franz; Staude, Jurgen
Bibcode: 2000ESASP.463..629V
Altcode: 2000sctc.proc..629V
  No abstract at ADS

Title: Multi-mode Magnetic Oscillations in Sunspots
Authors: Zhugzhda, Y.; Balthasar, H.; Staude, J.
Bibcode: 1999ESASP.448..417Z
Altcode: 1999mfsp.conf..417Z; 1999ESPM....9..417Z
  No abstract at ADS

Title: The Influence of the Adiabatic Coefficient and the Magnetic
    Field on Sunspot Oscillations
Authors: Settele, A.; Zhugzhda, Y. D.; Staude, J.
Bibcode: 1999ESASP.448..367S
Altcode: 1999ESPM....9..367S; 1999mfsp.conf..367S
  No abstract at ADS

Title: Oscillations in Sunspots: Observations and Modelling
Authors: Staude, J.; Rendtel, J.; Balthasar, H.; Zhugzhda, Y.
Bibcode: 1999ESASP.448..373S
Altcode: 1999ESPM....9..373S; 1999mfsp.conf..373S
  No abstract at ADS

Title: Determination of the Velocity Vector Field in an Asymmetric
    Sunspot Based on Vector Magnetograph Measurements
Authors: Krivtsov, A. M.; Hofmann, A.; Staude, J.; Klvaña, M.;
   Bumba, V.
Bibcode: 1999ASPC..184..108K
Altcode:
  A new method to determine the distribution of the full velocity
  vector in an asymmetric sunspot is presented. Measurements of the
  Doppler velocity and of the vector of the magnetic field are used as
  initial data for these calculations. The determination is subdivided
  into two stages: in a first step we obtain the distribution of the
  velocity projection onto the solar surface, and in the second step
  the orthogonal component of the velocity field is calculated. The
  resulting vector velocity field is in good agreement with the basic
  features of the siphon flow model of penumbral flux tubes.

Title: SUMER Observations of Intensity Oscillations in the Transition
    Region of a Sunspot
Authors: Rendtel, J.; Staude, J.; Innes, D. E.; Wilhelm, K.
Bibcode: 1999ASPC..184..271R
Altcode:
  UV spectroscopic data obtained with the SUMER spectrograph aboard SOHO
  have been analysed to detect oscillations in the chromosphere-corona
  transition region (TR) above sunspots. We observed the active region
  NOAA 7986 in the wavelength bands around the Ne VIII line at 770.4 Å
  and the C IV line at 1548.1 Å on August 29, 1996, between 09:08 UT
  and 13:31 UT. Simultaneous observations with the Normal Incidence
  Spectrometer of CDS aboard SOHO have shown, that the spot had a
  bright EUV plume at TR temperatures. A preliminary data analysis
  indicates intensity oscillations in the 2-minute range (7.3...7.9
  mHz) in both spectral lines. The temporal variation of oscillatory
  power in the two spectral lines is generally in opposite directions,
  i.e. during an increase of oscillatory power in the Ne VIII line we
  find a decrease in the C IV line. A similar but smaller tendency is
  observed in the average intensity of the line profiles. This hints at
  a non-adiabatic behaviour of the oscillations and a slow cooling of
  the emitting sunspot plume region.

Title: Sunspot Oscillations
Authors: Staude, J.
Bibcode: 1999ASPC..184..113S
Altcode:
  Sunspots show oscillations of velocity, of intensity, and probably
  of the magnetic field; the oscillations are observed at different
  periods (2-3 min, 5 min, &lt;= 20 min), at all height levels of the
  sunspot atmosphere, and with different spatial distributions and
  characteristic phase relations. In the present paper a short review
  on the various phenomena is given, with focusing on oscillations of
  the magnetic field at photospheric levels and on oscillations in the
  transition region to the corona above sunspots, derived from recent
  2-D observations with high spatial resolution. The observed data are
  compared with the predictions from theory and modelling.

Title: Magnetic field oscillations in sunspots - - a `whispering
    gallery' mode?
Authors: Staude, J.; Balthasar, H.; Zhugzhda, Y. D.
Bibcode: 1999AGAb...15....9S
Altcode: 1999AGM....15..A08S
  Oscillations of the magnetic field in the sunspot photosphere have been
  detected by recent high-resolution, two-dimensional, spectro-poarimetric
  observations at Tenerife and aboard the SOHO satellite. Their power is
  concentrated in isolated small flux bundles (pores) outside of larger
  umbrae and in patches at the boundary between umbra and penumbra of
  larger spots. The slow body mode of magneto-acoustic waves in an intense
  magnetic fluxtube provides an explanation of the strange appearance
  of such magnetic oscillations. This applies to small sunspots if the
  azimuth number m=0, but also to the small features piling up in rings
  at the border of the umbrae of larger sunspots. In the latter model
  the magnetic oscillations are the signature of the slow body mode with
  m &gt;&gt; 1, which bears a resemblance to the well-known whispering
  gallery mode in acoustics. The slow surface modes and fast body modes
  are also discussed.

Title: Third Advances in Solar Physics Euroconference: Magnetic
    Fields and Oscillations
Authors: Schmieder, B.; Hofmann, A.; Staude, J.
Bibcode: 1999ASPC..184.....S
Altcode:
  The third Advances in Solar Physics Euroconference (ASPE) "Magnetic
  Fields and Oscillations"concluded a series of three Euroconferences
  sponsored by the European Union. The meeting took place in Caputh
  near Potsdam, Germany, on September 22-25, 1998, followed by the JOSO
  (Joint Organization for Solar Observations) 30th Annual Board Meeting
  on September 26, 1998. The ASPE formula is attractive and compares well
  with other meetings with "show-and-tell" character. This meeting had
  122 participants coming from 26 countries; 36 participants came from
  countries formerly behind the Iron Curtain; a "politically incorrect"
  estimate says that 48 participants were below 35 years of age,
  with an unusually large female-to-male ratio. This characteristic of
  youngness is the more striking since solar physics is a perhaps overly
  established field exhibiting an overly senior age profile. It was a
  good opportunity to train this young generation in Solar Physics. The
  conference topic "Magnetic Fields and Oscillations" obviously was
  wide enough to cater to many an interest. These proceedings are
  organized according to the structure of the meeting. They include
  the topics 'High resolution spectropolarimetry and magnetometry',
  'Flux-tube dynamics', 'Modelling of the 3-D magnetic field structure',
  'Mass motions and magnetic fields in sunspot penumbral structures',
  'Sunspot oscillations', 'Oscillations in active regions - diagnostics
  and seismology', 'Network and intranetwork structure and dynamics',
  and 'Waves in magnetic structures'. These topics covered the first
  2.5 days of the conference. The reviews, oral contributions, and
  poster presentations were by no means all of the meeting. The ASPE
  formula also adds extensive plenary sessions of JOSO Working groups
  on topics that involve planning of Europe-wide collaboration. At this
  meeting these concerned solar observing techniques, solar data bases,
  coordination between SOHO and ground-based observing, and preparations
  for August 11, 1999 when more Europeans will be eclipsed than ever
  before. The contributions to these sessions have been included into
  the present volume as well. The participants of the EU-TMR Research
  Network 'Solar Magnetometry Network' came together to discuss in a
  special working group session questions of their future collaboration.

Title: An attempt to estimate nonideal effects on the electron
    partial pressure in the solar interior up to density order 5/2
Authors: Meister, C. -V.; Staude, J.; Pregla, A. V.
Bibcode: 1999AN....320...43M
Altcode:
  Helioseismology is probing the equation of state of the solar interior
  with ever increasing precision. Recently, even nonideal pressure
  modifications below 1 % are being considered, mainly due to the use of
  different partition functions. In the present paper only the electron
  partial pressure has been studied, and thus no partition function was
  taken into account. Instead, the pressure was calculated beyond the
  usually applied Debye-Huckel theory, and quantum-mechanical electron
  exchange was taken into account very carefully. If the total electron
  pressure at distances from the solar centre larger than 0.83 solar radii
  could be described by equilibrium thermodynamics, it proved smaller
  than the value for an ideal gas due to the dominating Debye-Huckel
  screening. On the contrary, at distances smaller than 0.83 solar radii
  electron exchange increases the total pressure up to values above the
  ideal pressure. Pressure modifications up to one per cent are caused
  by the higher-order interactions beyond the Debye-Huckel screening.

Title: Measurements of magnetic field strength on T Tauri stars
Authors: Guenther, Eike W.; Lehmann, Holger; Emerson, James P.;
   Staude, Jürgen
Bibcode: 1999A&A...341..768G
Altcode:
  We have investigated the magnetic field strength of one weak-line and
  four classical T Tauri stars. The magnetic field strength is derived
  from the differential change of the equivalent width of photospheric
  Fe I lines in the presence of a magnetic field, calculated using a
  full radiative transfer code. The method was successfully tested by
  applying it to a non-magnetic solar-type star, and to <ASTROBJ>VY
  Ari</ASTROBJ> which is believed to have a strong magnetic field. For
  two of the classical T Tauri stars, we find a product of magnetic
  field strength and filling factor B * f = (2.35+/- 0.15) kG for
  <ASTROBJ>T Tau</ASTROBJ>, and B * f = (1.1+/- 0.2) kG for <ASTROBJ>LkCa
  15</ASTROBJ>. For the classical T Tauri star <ASTROBJ>UX Tau A</ASTROBJ>
  and the weak-line T Tauri star <ASTROBJ>LkCa 16</ASTROBJ> the detection
  is only marginal, indicating magnetic field strengths of the order of
  1 kG and possibly of more than 2 kG, respectively. No field could be
  detected for the classical T Tauri star <ASTROBJ>GW Ori</ASTROBJ>. For
  the two classical T Tauri stars for which we have detected a field, we
  find the filling factors to be larger than ~ 0.5, which indicates that
  the magnetic field covers most of the photosphere. We also show that
  ignoring a magnetic field can, depending on the lines used, result in
  errors in effective temperature and underestimates of veiling. Based
  on observations made with the William Herschel Telescope operated
  on the island of La Palma by the Royal Greenwich Observatory in the
  Spanish Observatorio de los Roque de los Muchachos of the Instituto
  de Astrofisica de Canarias

Title: GREGOR, a 1.5 M Solar Telescope
Authors: von der Lühe, O.; Schmidt, W.; Soltau, D.; Kneer, F.;
   Staude, J.
Bibcode: 1999AGAb...15....5V
Altcode: 1999AGM....15..A01V
  We present the design of a new large solar telescope which is going to
  be installed at the Observatorio del Teide, in the tower that presently
  houses the 45cm Gregory-Coudé-Telescope. The new telescope has an
  aperture of 1.5 meters and its optical design is basically a Gregorian
  configuration. It will be an open telescope in an azimuthal mount. An
  adaptive optics system is incorporated in the optical design as well as
  a polarimetry package. The feasibility of lightweight optics for the
  primary mirror has been investigated in an industrial pre-study. The
  focal plane instrumentation will include a high resolution filter
  spectrometer similar to the existing TESOS instrument at the VTT and
  a new spectro-polarimeter for the visible and the near UV. The latter
  instrument is presently being developed jointly by the KIS and the
  High Altitude Observatory in Boulder, USA. Budget permitting, detailed
  (Phase-B) planning will start in 2000, and the telescope will be
  developed and built in 2002 and 2003 with first light in spring of 2004.

Title: Max-Planck-Institut für Astronomie,
    Heidelberg-Königstuhl. Jahresbericht 1997.
Authors: Staude, J.; Appenzeller, I.; Bührke, T.
Bibcode: 1999mfah.bookQ....S
Altcode:
  No abstract at ADS

Title: A new method to calculate the resonant response of a sunspot
    model atmosphere to magneto-atmospheric waves
Authors: Settele, A.; Zhugzhda, Y. D.; Staude, J.
Bibcode: 1999AN....320..147S
Altcode:
  In order to understand the observed oscillations in sunspots we
  present a new method for calculating the resonant response of a
  realistic semi-empirical model of the sunspot umbral atmosphere and
  subphotosphere to magneto-atmospheric waves in a vertical magnetic
  field. The depth dependence of both the adiabatic coefficient and the
  turbulent pressure is taken into account. This requires an extension
  of the wave equations by Ferraro &amp; Plumpton (1958). We compare
  the coefficients of wave transmission, reflection, and conversion
  between fast mode and slow mode waves for different assumptions,
  compare the results with those from earlier modelling efforts, and
  point out possible sources of mistakes. The depth dependence of the
  adiabatic coefficient strongly influences the resulting spectrum of
  resonance frequencies. The condition of a conservation of wave flux
  is violated if the depth dependence of the turbulent pressure is not
  properly considered.

Title: High resolution spectro-polarimetric observations of sunspot
    penumbrae.
Authors: Maleki, D.; Staude, J.
Bibcode: 1999joso.proc...85M
Altcode:
  Spectro-polarimetric observations with high spatial resolution have
  been obtained in sunspot penumbrae and used to derive the magnetic
  field structure in different filamentary fine structures. Some results
  from a preliminary data analysis are listed.

Title: Magnetic fields and oscillations. 3rd Euroconference ASPE98
    (Advances in Solar Physics Euroconference 1998), Potsdam/Caputh
    (Germany), 22 - 25 Sep 1998. Poster contributions.
Authors: Schmieder, B.; Staude, J.
Bibcode: 1999joso.proc...74S
Altcode:
  All of the oral presentations of ASPE98 will be published in a separate
  volume of the ASP Conference Series, while this volume contains the
  poster presentations.

Title: Magnetic Field Oscillations in Sunspots?
Authors: Staude, Juergen; Balthasar, Horst; Zhugzhda, Yuzef
Bibcode: 1999soho....9E..25S
Altcode:
  Oscillations of velocity and intensity are known for more than 2
  decades; they are observed in spectral lines formed at different height
  levels of the sunspot atmosphere. The interpretation of measurements
  of magnetic field oscillations, however, is still contradictory. We
  give evidence of the presence of such oscillations and describe the
  observed properties. The basic features of their spatial structure
  can be explained by slow body waves in intense magnetic flux tubes. In
  particular, a `whispering gallery'-like mode could be an appropriate
  model.

Title: Max-Planck-Institut für Astronomie,
    Heidelberg-Königstuhl. Jahresbericht 1998.
Authors: Staude, J.; Appenzeller, I.; Bührke, T.
Bibcode: 1999mfah.bookR....S
Altcode:
  No abstract at ADS

Title: Determination of the full velocity vector based on vector
    magnetograph measurements in an asymmetric sunspot
Authors: Krivtsov, A. M.; Hofmann, A.; Staude, J.; Klvana, M.;
   Bumba, V.
Bibcode: 1998A&A...335.1077K
Altcode:
  A new method to determine the distribution of the full velocity
  vector in an asymmetric sunspot is presented. Measurements of the
  Doppler velocity and of the vector of the magnetic field are used as
  initial data for these calculations. The determination is subdivided
  into two stages: in a first step we obtain the distribution of the
  velocity projection onto the solar surface, and in the second step
  the orthogonal component of the velocity field is calculated. The
  method has been applied to a sunspot observed from two observatories
  over 7 days, that is at different positions on the solar disk and in
  different phases of its development. The resulting vector velocity
  field is in good agreement with the basic features of the siphon flow
  model of penumbral flux tubes. The velocities are directed outwards
  from the sunspot, and they have small values in the umbra and maximum
  values in the central part of the penumbra, while in the outer penumbra
  the velocities decrease rapidly. The vertical velocities are mainly
  localized at the umbral boundary (upflows) and at the outer parts of
  the penumbra (downflows).

Title: German-Russian Cooperation in Helioseismology
Authors: Horn, T.; Hasler, K. -H.; Arlt, K.; Staude, J.; Oraevsky,
   V. N.; Zhugzhda, Y. D.
Bibcode: 1998ESASP.417..243H
Altcode: 1998cesh.conf..243H
  No abstract at ADS

Title: Sunspot Oscillations from SUMER Spectra
Authors: Rendtel, J.; Staude, J.; Innes, D.; Wilhelm, K.; Gurman, J. B.
Bibcode: 1998ESASP.417..277R
Altcode: 1998cesh.conf..277R
  No abstract at ADS

Title: Oscillations in a Sunspot Transition Region Observed with SOHO
Authors: Staude, J.; Rendtel, J.; Innes, D.; Wilhelm, K.; Gurman, J. B.
Bibcode: 1998ESASP.418..651S
Altcode: 1998soho....6..651S
  Measurements of oscillations in the chromosphere-corona transition
  region (TR) above sunspots are of fundamental importance for
  investigating sunspot structure and dynamics; for instance, resonator
  models of magneto-atmospheric waves and their non-adiabatic behavior
  can be tested in this way (Staude et al., 1985). UV spectroscopic
  data obtained with the SUMER spectrograph aboard SOHO have been
  analyzed to detect such oscillations. The longest time series was
  obtained on August 29, 1996, between 09:08 UT and 13:31 UT. During
  this period, scans were made over the active region NOAA 7986 in the
  wavelength bands around 770.4 AA (Ne VIII line, formed at T ~6 times
  10<SUP>5</SUP> K) and 1548.1 AA (C IV line, T ~7 times 10<SUP>4</SUP>
  dots 1.3 times 10<SUP>5</SUP> K). The large dominating sunspot of this
  active region was close to the disk centre. Simultaneous observations
  with the Normal Incidence Spectrometer of CDS aboard SOHO have shown,
  that the spot had a bright EUV plume at TR temperatures (Maltby et al.,
  1998). For compensating possible instrumental and exposure effects,
  we extract background information from each image. A preliminary
  data analysis indicates intensity oscillations in the 2-minute range
  (at 7.4 dots 7.7 mHz) in both spectral lines and a slow temporal
  decrease of oscillatory power in the Ne VIII line, but an increase
  in the C IV line. These results hint at a non-adiabatic behavior of
  the oscillations and a slow cooling of the emitting sunspot plume
  region. Further supplementary observations of the active region NOAA
  7986 are from EIT aboard SOHO (in the Fe IX/X lines at 171 AA ---
  T ~1.3 times 10<SUP>6</SUP> K --- a time series of 2 hours has been
  obtained simultaneous to the first part of the SUMER series, moreover,
  single high-resolution pictures in 4 UV lines exist) as well as from
  the magnetograph of the Einsteinturm observatory at Potsdam showing
  a rather complex polarity distribution. It is planned to extend the
  study towards velocity variations and to correlations between the
  oscillations in the two SUMER lines. Furthermore, correlations will
  be investigated towards the EIT time series.

Title: Oscillations of the magnetic field in an active region
Authors: Horn, T.; Staude, J.
Bibcode: 1998IAUS..185..449H
Altcode:
  In 1994 we performed observations at the German Vacuum Tower Telescope
  at the Observatorio del Teide (Tenerife) using a polarimeter in front
  of a two-dimensional imaging spectrometer with a tunable narrow-band
  Fabry-Perot interferometer. We observed the main sunspot of the active
  region NOAA 7577 and measured the Doppler line shift and the Zeeman
  splitting of the line Fe I 6173 AA. The data show significant power of
  velocity and magnetic field oscillations in period bands at 3 min and 5
  min, a strong coherence of the velocity and magnetic field oscillations,
  and a clear dependence of the phase difference on the period and on
  the position, pointing out a longitudinal character of the oscillations.

Title: Oscillation of the magnetic field in an active region.
Authors: Horn, T.; Staude, J.
Bibcode: 1998joso.proc...79H
Altcode:
  The solar vacuum telescope VTT at Tenerife has been used to obtain
  high-resolution two-dimensional spectro-polarimetric observations
  of oscillations in the photospheric layers of sunspots. The spectra
  of velocity oscillations show the known features of closely packed
  power peaks in bands of periods around 3 min (strengthened) and 5
  min (weakened with respect to the quiet Sun). In the same frequency
  bands the VTT data show significant oscillations of the magnetic
  field strength as well, which could not be attributed to disturbing
  influences. Maximum power of both velocity and magnetic oscillations and
  a strong correlation between them, in the 3-min band in particular,
  is found to occur in those parts of the umbra where the magnetic
  lines of force are parallel to the line-of-sight. The oscillations are
  characterized by a marked spatial fine structure and a non-stationary
  behaviour.

Title: Two-dimensional measurements of sunspot oscillations
Authors: Staude, J.; Horn, T.
Bibcode: 1997ASSL..225..235S
Altcode: 1997scor.proc..235S
  High-resolution two-dimensional spectro-polarimetric observations
  of oscillations in the photospheric layers of a sunspot have been
  obtained using the Vacuum Tower Telescope at Tenerife. A Fabry-Perot
  interferometer has been applied to get narrow-band filtergrams directly
  and to scan through the line profile. The spectra show significant power
  of oscillations of velocity $v$ and of the magnetic field strength
  as well. Both are concentrated in bands of peaks at periods around
  3 min ($v$ strengthened) and 5 min ($v$ weakened with respect to the
  quiet Sun), with maxima occuring in those parts of the umbra where the
  magnetic lines of force are parallel to the line-of-sight. Coherence
  and the phase difference between both types of oscillations show a
  clear dependence on the magnetic field direction as well.

Title: Observations of Sunspot Umbral Oscillations
Authors: Horn, T.; Staude, J.; Landgraf, V.
Bibcode: 1997SoPh..172...69H
Altcode: 1997ESPM....8...69H
  The solar vacuum telescopes VTT and GCT at Tenerife have been used to
  obtain high-resolution two-dimensional spectro-polarimetric observations
  of oscillations in the photospheric layers of sunspots. At the GCT
  the area of the sunspot has been scanned by shifting the spectrograph
  slit; at the VTT a Fabry-Pérot interferometer has been applied to get
  narrow-band filtergrams directly and to scan through the line profile.

Title: Contribution Functions for Polarized Radiative Transfer
Authors: Staude, J.
Bibcode: 1996SoPh..164..183S
Altcode:
  The concepts of contribution functions (CF) and of mean depths of line
  formation of unpolarized light as well as of Stokes profiles will be
  critically discussed. After having outlined the historical development
  arguments are given in favour of the use of directly observable
  quantities such as the emergent line intensity or the polarized
  components seen through polarization optics only. The arguments are
  provided by a probability interpretation of the CF; the ambiguities
  of line depression CF as well as some physically strange features in
  Stokes profiles are avoided if the rules based on this interpretation
  are observed. Some problems of the interpretation of measurements in
  chromospheric lines will be discussed as well.

Title: Two-dimensional measurements of sunspot oscillations.
Authors: Staude, J.; Horn, T.; Landgraf, V.
Bibcode: 1996AGAb...12...91S
Altcode:
  No abstract at ADS

Title: Spectral darkening functions of solar p-modes - an effective
    tool for helioseismology.
Authors: Zhugzhda, Y. D.; Staude, J.; Bartling, G.
Bibcode: 1996A&A...305L..33Z
Altcode:
  Darkening functions (contrasts) of intensity fluctuations due to waves
  in a nongrey LTE model of the solar atmosphere are calculated for
  different wavelengths λ in the optical continuum spectrum. Adiabatic
  and isothermal acoustic waves as well as temperature waves are
  considered. A change of the sign of the darkening function for certain
  ranges of λ is revealed for adiabatic waves. This effect makes it
  possible to observe modes with l&gt;=3 even in stars. Observations of
  the darkening function of p-modes at different λ are proposed as a
  new tool, making it possible to check numerical models of p-modes, to
  impose restraints to the choice of the boundary conditions, to reduce
  the arbitrariness in the calculation of nonadiabatic corrections
  to eigenfrequencies, and to improve the accuracy of solar interior
  sounding in this way.

Title: On the possibility of detection of p-modes with L&gt; 3 in
    the sun-like stars
Authors: Staude, J.; Zhugzhda, Y. D.
Bibcode: 1996ASPC..109..161S
Altcode: 1996csss....9..161S
  No abstract at ADS

Title: An analytic theory of adiabatic p-modes in the atmospheres
    of the Sun and Sun-like stars.
Authors: Dzhalilov, N. S.; Staude, J.
Bibcode: 1995A&A...303..561D
Altcode:
  The height profile of temperature T of the solar or a stellar model,
  extending from the subphotosphere through the atmosphere up to the
  corona, has been piecewise approximated by various nonlinear and linear
  functions for the different regions. Solving the basic equations of
  adiabatic, nonvertical oscillations for these regions in the Cowling
  approximation we obtained the eigenfunctions for the p-modes in
  analytic form. Using these exact solutions it has been demonstrated,
  that the mechanism of resonant transmission of acoustic waves through
  the considered layers is sufficient to explain the main features of
  the observed frequency spectrum of the solar p-modes, including the
  5-min oscillations and the peaks in the high-frequency tail. It has
  been shown that the upper turning point of the resonator for low
  frequencies ν&lt;~4mHz does not coincide with the boundary of the
  acoustic potential barrier, the latter extending from the steep gradient
  of T at the upper subphotosphere up to that above the minimum of T. The
  wakes of the waves penetrate deep into the barrier (up to a height
  of 500km in the solar atmosphere) and are reflected from there. High
  frequencies are reflected from the chromosphere-corona transition
  region. For not any frequency there exists a total reflection; with
  increasing frequency there is an increasing leakage of wave energy
  into the corona. It has been shown that all observable characteristics
  of oscillations depend directly on the phase shift {DELTA}φ between
  upward and downward running waves. The resonance peaks in the spectrum
  arise at {DELTA}φ=0, where {DELTA}φ has been defined in the limits
  [-π, +π]. The dependence of the power spectrum on the height, on
  the frequency, and on the degree l has been demonstrated. The first
  resonant frequencies always correspond to the 5-min oscillations.

Title: Solar Irradiance Oscillations: Preliminary Results of the
    Coronas-Difos Experiment
Authors: Lebedev, N. I.; Oraevsky, V. N.; Zhugzhda, Y. D.; Kopaev,
   I. M.; Kostyk, R. I.; Pflug, K.; Rüdiger, G.; Staude, J.; Bettac,
   H. -D.
Bibcode: 1995ESASP.376b.353L
Altcode: 1995soho....2..353L; 1995help.confP.353L
  No abstract at ADS

Title: An Analytical Model of Adiabatic P-Modes Resonant Transmission
    Through the Solar Atmosphere
Authors: Dzhalilov, N. S.; Staude, J.
Bibcode: 1995ESASP.376b.441D
Altcode: 1995soho....2..441D; 1995help.confP.441D
  No abstract at ADS

Title: First results of the CORONAS-DIFOS experiment. Space
    observations of solar irradiance oscillations.
Authors: Lebedev, N. I.; Oraevsky, V. N.; Zhugzhda, Y. D.; Kopaev,
   I. M.; Kostyk, R. I.; Pflug, K.; Ruediger, G.; Staude, J.; Bettac,
   H. -D.
Bibcode: 1995A&A...296L..25L
Altcode:
  The DIFOS experiment aboard the satellite CORONAS has been designed to
  observe irradiance fluctuations due to global solar oscillations. The
  satellite was launched on March 2, 1994. It uses a photometer measuring
  fluctuations of the solar flux in three channels: near 550nm, 750nm,
  and from 400nm through 1.1μm. After a short description of the
  instrumentation and the data analysis we present first, preliminary
  results of observations of low-degree p-modes including their variation
  in time.

Title: Book-Review - Robotic Telescopes in the 1990S
Authors: Filippenko, A. V.; Staude, J.
Bibcode: 1995AN....316..154F
Altcode:
  No abstract at ADS

Title: Visibility Functions of Solar and Stellar Irradiance Variations
Authors: Staude, J.; Bartling, G.; Zhugzhda, Y. D.; Dzhalilov, N. S.
Bibcode: 1995ASPC...83..451S
Altcode: 1995IAUCo.155..451S; 1995aasp.conf..451S
  No abstract at ADS

Title: An Analytic Theory of Adiabatic p-modes in the Atmospheres
    of the Sun and Sun-like Stars
Authors: Dzhalilov, N. S.; Staude, J.
Bibcode: 1995ASPC...83..449D
Altcode: 1995IAUCo.155..449D; 1995aasp.conf..449D
  No abstract at ADS

Title: Sonnenforschung am Sonnenobservatorium Einsteinturm des
    Astrophysikalischen Instituts Potsdam.
Authors: Staude, J.
Bibcode: 1995epaa.book...98S
Altcode:
  No abstract at ADS

Title: Sonnenforschung am Einsteinturm.
Authors: Staude, J.
Bibcode: 1995Stern..71..142S
Altcode:
  No abstract at ADS

Title: Radiation-Hydrodynamic Waves and Solar P Modes: Visibility
    Functions
Authors: Staude, J.; Zhugzhda, Y. D.; Dzhalilov, N. S.
Bibcode: 1995ASPC...76..338S
Altcode: 1995gong.conf..338S
  No abstract at ADS

Title: Radiation-hydrodynamic waves in an optically grey
    atmosphere. II. Analysis of wave properties and effects of thermal
    conductivity in a homogeneous model.
Authors: Dzhalilov, N. S.; Zhugzhda, Y. D.; Staude, J.
Bibcode: 1994A&A...291.1001D
Altcode:
  The properties of radiation-hydrodynamic waves in a radiative,
  thermally conducting, uniform atmosphere are investigated, avoiding the
  Eddington approximation and considering a temporal as well as a spatial
  analysis. The analysis of the dispersion equation shows the existence
  of acoustic, radiation, and thermal wave modes and a relaxation mode
  as well. The generalized Spiegel formula is discussed and the accuracy
  of the Eddington approximation for the radiation-hydrodynamic waves
  is considered. The amplitudes and phases of disturbances of gas
  and radiation pressure, intensity, and temperature are obtained for
  standing and travelling waves and for the relaxation mode too. The
  polar angle dependence of the phase shift between velocity and intensity
  is investigated. The predictions for full-disk intensity observations
  and the deficiencies of earlier, less complete approaches are discussed.

Title: Radiation Hydrodynamic Waves and Global Solar Oscillations
Authors: Staude, J.; Dzhalilov, N. S.; Zhugzhda, Y. D.
Bibcode: 1994SoPh..152..227S
Altcode: 1994IAUCo.143..227S; 1994svs..coll..227S
  We investigate nonadiabatic hydrodynamic waves in a nongrey, radiating,
  thermally conducting, homogeneous atmosphere in LTE with a finite mean
  free path of photons. Avoiding the Eddington approximation the remaining
  simplifications in the basic equations are discussed, the generalized
  dispersion relation is analysed, and some wave properties in a grey
  model are studied. The properties of waves in a stratified atmosphere
  are analysed as well. In connection with the predicted properties of
  the nonadiabatic waves we discuss observations ofp-modes by measuring
  brightness fluctuations.

Title: Sunspot umbral oscillations
Authors: Staude, J.
Bibcode: 1994smf..conf..248S
Altcode:
  No abstract at ADS

Title: Interpretation of sunspot oscillations
Authors: Staude, J.
Bibcode: 1994ASIC..433..189S
Altcode:
  No abstract at ADS

Title: Visibility functions of solar and stellar luminosity
    oscillations.
Authors: Staude, J.; Bartling, G.; Dzhalilov, N. S.; Zhugzhda, Y. D.
Bibcode: 1994AGAb...10..116S
Altcode:
  No abstract at ADS

Title: Sonnenforschung in Potsdam - Das Sonnenobservatorium
    Einsteinturm des Astrophysikalischen Instituts Potsdam.
Authors: Staude, J.
Bibcode: 1994ABLD....5.....S
Altcode:
  Contents: 1. Das Astrophysikalische Observatorium
  Potsdam. 2. Die Relativitätstheorie. 3. Instrumentarium des
  Einsteinturms. 4. Forschungsprogramm. 5. Das Astrophysikalische
  Institut Potsdam.

Title: Radiation-Hydrodynamic Waves in the Solar Atmoshere
Authors: Zhugzhda, Y. D.; Staude, J.; Dzhalilov, N. S.
Bibcode: 1994emsp.conf....9Z
Altcode:
  No abstract at ADS

Title: Radiation-hydrodynamic waves in an optically non-grey
    atmosphere
Authors: Zhugzhda, Y. D.; Dzhalilov, N. S.; Staude, J.
Bibcode: 1993A&A...278L...9Z
Altcode:
  We derive the dispersion equation of radiation-hydrodynamic waves for
  a nongrey atmosphere in Local Thermodynamic Equilibrium (LTE) avoiding
  the Eddington approximation. It is shown that the Rosseland mean opacity
  doesn't describe the relaxation processes in the atmosphere except the
  opaque limit. For the transparent limit the relaxation time depends on
  the so-called Newton mean opacity. The grey and nongrey approximations
  are compared for a model of the solar photosphere.

Title: Planeten - Wanderer im All
Authors: Lang, Kenneth R.; Whitney, Charles A.; Staude, J.; Bührke, T.
Bibcode: 1993pwia.book.....L
Altcode:
  In allgemeinverständlicher Form und ohne fachliche Vorkenntnisse
  beim Leser vorauszusetzen stellen die Autoren unser Planetensystem
  vor. Der klar geschriebene Text wird durch eine Fülle
  z.T. bisher unveröffentlichter Fotos aufgelockert, und die
  Ergebnisse von Raumsonden- und Satellitenmissionen bis 1992 sind
  berücksichtigt. "...besticht durch exzellentes Bildmaterial und
  Stilsicherheit in der Formulierung. Die Autoren erklären astronomische
  Sachverhalte umfassend und leichtverständlich. Der Leser erlebt
  einen faszinierenden Raumflug durch unser Sonnensystem...Mit sinnvoll
  eingeschobenen Zusammenfassungen und Kurzinformationen, umfassendem
  Anhang, Register und Bilbliographie. Ein ideales Buch für interessierte
  Laien und angehende Astronomen." (Westdeutsche Zeitung)

Title: Book-Review - the Sun - a Laboratory for Astrophysics
Authors: Schmelz, J. T.; Brown, J. C.; Staude, J.
Bibcode: 1992AN....313..348S
Altcode:
  No abstract at ADS

Title: Book-Review - the Sun and Cool Stars - Activity Magnetism
    Dynamos - I.A.U.COLL - Helsinki 1990JUL17-20
Authors: Tuominen, I.; Moss, D.; Rudiger, G.; Staude, J.
Bibcode: 1992AN....313..318T
Altcode:
  No abstract at ADS

Title: Book-Review - Solar Observations - Techniques and
    Interpretation - First Canary Islands Winter School of Astrophysics
Authors: Sanchez, F.; Collados, M.; Vazquez, M.; Staude, J.
Bibcode: 1992AN....313Q.302S
Altcode:
  No abstract at ADS

Title: Radiation-hydrodynamic waves in an optically gray atmosphere. I
    - Homogeneous model
Authors: Dzhalilov, N. S.; Zhugzhda, Y. D.; Staude, J.
Bibcode: 1992A&A...257..359D
Altcode:
  We consider the coupled set of equations of hydrodynamics and
  radiative transfer. Only radiative transfer is taken into account
  in the energy equation, while other mechanisms of heat transfer
  are ignored. Disturbances of the tensor of radiative pressure are
  included in the linearized momentum equation. This term proves to be
  of great importance for radiation-acoustic waves. LTE as well as a
  gray approximation and homogeneity of the atmosphere are assumed. The
  hydrodynamic equations are solved by using an exact solution of the
  radiative transfer equation (no Eddington approximation is made). The
  dispersion equation for the nonadiabatic oscillations is derived. This
  equation is valid for arbitrary optical thickness and generalizes all
  hitherto known results.

Title: Oscillations &amp;Seismological Diagnostics of Sunspots
    (Invited)
Authors: Staude, J.
Bibcode: 1992LNP...397..181S
Altcode: 1992sils.conf..181S
  Comparisons between recent observations of umbrae and detailed numerical
  model calculations have achieved a substantial agreement. This implies
  that the hitherto developed models for the structure and dynamics of
  sunspot umbrae seem to reflect essential features of the nature of
  sunspots, notwithstanding the various simplifying assumptions. Recent
  analytic calculations for simplified umbral models also confirmed
  our model of a system of umbral resonators (Campos, 1989; Evans and
  Roberts, 1990); Campos (1989) only argued in favour of an additional
  resonator for pure Alfvén waves. The model provides an important tool
  for sounding subphotospheric and atmospheric layers of sunspots and
  possibly of other magnetized stellar atmospheres. Further observations
  of oscillations should try to improve the spatial resolution on the
  sun and the coverage of the data in space and time. Model calculations
  should abandon the restrictive assumptions by considering nonlinear
  and nonadiabatic processes such as radiative dissipations of waves and,
  moreover, self-consistent calculations of wave propagation and non-LTE
  line formation are needed to improve the diagnostics.

Title: Das Sonnenobservatorium Einsteinturm in Potsdam. Erforschung
    solarer Magnetfelder und der Physik von Sonnenflecken.
Authors: Staude, J.
Bibcode: 1991S&W....30..505S
Altcode:
  No abstract at ADS

Title: Book-Review - Dynamics of Quiescent Prominences -
    I.A.U. COLL.117 - Hvar - Croatia
Authors: Ruzdjak, V.; Tandberg-Hanssen, E.; Staude, J.
Bibcode: 1991AN....312..326R
Altcode:
  No abstract at ADS

Title: The Potsdam vector magnetograph: methodical experiences
    and results.
Authors: Staude, J.; Hofmann, A.; Bachmann, G.
Bibcode: 1991sopo.work...49S
Altcode:
  After a short historical introduction the instrumentation of the double
  line vector magnetograph is described as it is working in connection
  with the tower telescope of the Solar Observatory "Einsteinturm"
  at Potsdam. Subsequently the authors outline the calibration of the
  instrumental response to incident polarised light. The theoretical
  calibration of deriving the magnetic field components from the
  observed Stokes profiles is the next step. Finally the authors give a
  few examples of vector magnetograms and outline some of their methods
  for deriving further information from the magnetograms.

Title: Solar Research at Potsdam: Papers on the Structure and Dynamics
    of Sunspots.
Authors: Staude, J.
Bibcode: 1991RvMA....4...69S
Altcode:
  No abstract at ADS

Title: Book-Review - Energetic Phenomena on the Sun
Authors: Kundu, M. R.; Woodgate, B.; Schmahl, E. J.; Staude, J.
Bibcode: 1990AN....311..416K
Altcode:
  No abstract at ADS

Title: Book-Review - Asymptotics of High Order Differential Equations
Authors: Paris, R. B.; Wood, A. D.; Staude, J.
Bibcode: 1990AN....311..425P
Altcode:
  No abstract at ADS

Title: Book-Review - the Physics of Solar Flares
Authors: Tandberg-Hanssen, E.; Emslie, A. G.; Staude, J.
Bibcode: 1990AN....311..106T
Altcode:
  No abstract at ADS

Title: Seismological diagnostics of sunspot umbral structure.
Authors: Staude, J.
Bibcode: 1990PDHO....7..302S
Altcode:
  No abstract at ADS

Title: Book-Review - Advances in - and Asteroseismology -
    I.A.U. SYMP.123
Authors: Christensen-Dalsgaard, J.; Frandsen, S.; Staude, J.
Bibcode: 1989AN....310..280C
Altcode:
  No abstract at ADS

Title: Probing of Sunspot Umbral Structure by Oscillations
Authors: Zhugzhda, Y. D.; Staude, J.; Locans, V.
Bibcode: 1989ASIC..263..601Z
Altcode: 1989ssg..conf..601Z
  No abstract at ADS

Title: Book-Review - Solar and Stellar Physics - 5TH European Solar
    Meeting - Titisee / Schwarzwald - Germany - 1987APR27-30
Authors: Schroter, E. H.; Schussler, M.; Staude, J.
Bibcode: 1989AN....310...66S
Altcode:
  No abstract at ADS

Title: Possibilities and Problems of the Interpretation of Solar
    Magnetograph Measurements and Applications to Flare-Active Regions
Authors: Staude, J.; Hofmann, A.
Bibcode: 1989ESASP.285..123S
Altcode: 1989rsp..conf..123S
  The basic uncertainties encountered in the interpretation of
  magnetograph data, and possibilities for deriving more reliable
  information are reviewed. The problems are illustrated by describing
  the data handling of a vector magnetograph. Examples of observed
  flare-active regions demonstrate the state of information which can
  be obtained.

Title: Oscillations and the temperature minimum in sunspot umbrae
Authors: Locans, V.; Skerse, D.; Staude, J.; Zhugzhda, Iu. D.
Bibcode: 1988A&A...204..263L
Altcode:
  Observed umbral oscillation with periods of 2 - 3 min can be explained
  by slow-mode longitudinal magnetoatmospheric waves which are partly
  trapped in the umbral photosphere and chromosphere. Detailed numerical
  calculations for such a resonator in semi-empirical model atmospheres
  predict details of umbral oscillations which, after comparison with
  observed data, provide new information on the atmospheric structure. The
  results support arguments in favour of a low value of the temperature
  minimum (≤3000K) in the dark parts of umbrae, while the oscillations
  are deteriorated in bright umbral structures such as dots or light
  bridges.

Title: A two-component working model for the atmosphere of a large
    sunspot umbra
Authors: Obridko, V. N.; Staude, J.
Bibcode: 1988A&A...189..232O
Altcode:
  A two-component working model for the atmosphere of the umbra of a
  typical large sunspot is proposed which represents an improvement
  over the earlier Wroclaw-Ondrejov sunspot model. The main component
  is assumed to consist of cold matter at photospheric levels, a thin
  chromosphere, a shallow transition region, and a deep-set corona. The
  secondary component in the model has a volume filling factor of
  5-10 percent at all heights and is suggested to consist of thin
  fine-structure elements which are elongated parallel to the magnetic
  field. The present model is able to account for the basic features of
  sunspot observations at frequencies from X-rays up to microwaves.

Title: Oscillations and waves in sunspots.
Authors: Staude, J.; Zhugzhda, Iu. D.; Locans, V.
Bibcode: 1987PAICz..66..161S
Altcode: 1987eram....1..161S
  The authors review the basic features of oscillations observed at
  different height levels in the sunspot atmosphere, moreover, various
  possibilities for a theoretical interpretation are discussed.

Title: The interpretation of oscillations in sunspot umbrae
Authors: Zhugzhda, Iu. D.; Locans, V.; Staude, J.
Bibcode: 1987AN....308..257Z
Altcode:
  Possibilities for an interpretation of oscillations observed
  in several period bands (3 min, 5 min, 20 min) and at different
  heights in sunspot umbrae are reviewed. At subphotospheric depths
  two independent resonators are acting: a resonator for slow,
  quasi-transverse waves which can explain the lifetimes of bright
  umbral dots (greater than or equal to 20 sec), and a resonator for fast
  (acoustic), quasi-longitudinal waves which could result in the 5-min
  oscillations. The acoustic resonator strongly couples with the slow-mode
  longitudinal resonator at photospheric and chromospheric heights, the
  latter producing the resonance peaks in the 3-min period band. The whole
  scheme of resonance levels generalizes and corroborates a chromospheric
  resonator model earlier proposed by the present authors. Comparisons
  with alternative models and recent measurements show that the present
  model most naturally explains the majority of observed data.

Title: Electric current density in the sunspot photosphere derived
    from vector magnetograms.
Authors: Hofmann, A.; Staude, J.
Bibcode: 1987PAICz..66..105H
Altcode: 1987eram....1..105H
  The authors present observational results from which they determine
  azimuthal currents flowing across the magnetic field.

Title: Models of the solar atmosphere above sunspots
Authors: Staude, J.
Bibcode: 1986CoSka..15..299S
Altcode:
  The "Wroclaw-Ondřejov sunspot model", together with its recent
  improvements, provides a unified working model based on self-consistent
  physical assumptions for a large of heights from the deepest
  photospheric levels up to the lower corona. Using the WOSM together
  with emission models developed for various wavelength regions, the
  theoretically predicted emissions have been beautifully checked by
  comparison with new observed data.

Title: Spektroskopische Untersuchungen am Einsteinturm: Zur Physik
    der Korona und der Sonnenflecken.
Authors: Staude, J.
Bibcode: 1986Stern..62..109S
Altcode:
  No abstract at ADS

Title: Investigation of the large preceding spot of AR 2779 from
    SMM data
Authors: Siarkowski, M.; Jakimiec, J.; Staude, J.
Bibcode: 1986CoSka..15..111S
Altcode:
  Complex data from the SMM spacecraft (UVSP and XRP/FCS) have been
  used to investigate the structure and dynamics of the large p spot
  of the active region NOAA 2779 from November 1980. The spot shows an
  inhomogeneous structure characterized by a light bridge. In comparison
  with the darkest photospheric umbral cores the light bridge is
  bright in the photosphere and the transition region, but darker in the
  chromosphere. In the transition region the authors found upward motions
  above the umbra, but downward motions in the light bridge. Compared to
  the spot's surroundings the Ly-α emission is stronger above the umbra
  up to a factor of 3, but its spatial distribution is more inhomogeneous
  than the photospheric emission.

Title: Oscillations in the chromosphere and transition region above
    sunspot umbrae - A photospheric or a chromospheric resonator?
Authors: Zhugzhda, Ia. D.; Locans, V.; Staude, J.
Bibcode: 1985A&A...143..201Z
Altcode:
  A model for a chromospheric resonator for slow waves is proposed,
  and its basic features are compared with those of the model for a
  photospheric resonator for fast waves, proposed by Thomas and Scheuer
  (1982), (TS). Moreover, the model predictions are tested for agreement
  with recent observations of umbral oscillations. The observations in
  the umbral chromosphere and transition region are in agreement with the
  model presented but are difficult to reconcile with the TS model. This
  conclusion does not exclude the possibility that a TS-type photospheric
  resonator is excited as well. Finally, necessary improvements in the
  existing simplified theories are outlined.

Title: On the inhomogeneous structure of the chromosphere-corona
    transition region above sunspot umbrae
Authors: Staude, J.
Bibcode: 1985AN....306..197S
Altcode:
  Recent multiple wavelength observations of sunspot umbrae are
  explained within the framework of an inhomogeneous, two-component
  model of the structure of the umbral transition region, the
  Wroclaw-Ondrejov model. Simple analytical expressions for the
  atmospheric structure in each component, and in the lower corona,
  are derived and the free parameters were fitted to observations of
  EUV emission line intensities. It is shown that the main component of
  the umbral transition has a shallow transition region and a deep set
  corona. The second 'active' component displayed a large transition
  region embedded in the main coronal component.The spatial filling
  factor of the active component was about 5-10 percent in sunspots having
  bright EUV plumes. For sunspots without bright EUV plumes, the spatial
  filling factor was more than ten times smaller. The EUV emission line
  intensities are compared to temperature measurements in both quiet
  and active sunspot regions and the results are discussed in detail.

Title: Interpretation of Oscillations in Ultraviolet Lines Observed
    above Sunspot Umbrae
Authors: Staude, J.; Zhugzhda, Iu. D.; Locans, V.
Bibcode: 1985SoPh...95...37S
Altcode:
  Our theory of a resonator for slow magneto-atmospheric waves in the
  chromosphere of a sunspot umbra has been used to check different models
  of the structure of the chromosphere and transition region. Oscillations
  of velocity and intensity in CIV, SiIV, and OIV lines observed by
  Gurman et al. (1982) on the SMM spacecraft have been compared with
  the calculated oscillations. The observed spectrum of resonant
  peaks could well be explained by a gradient model of the umbral
  chromosphere. Different assumptions concerning the structure of the
  transition region do not influence the calculated resonance periods, but
  the amplitudes and phases of oscillations are modified. There is strong
  evidence for a concentration of the observed oscillations in cold fine
  structure elements of the transition region, even if the filling factor
  of such elements is very small (some few percent). Isothermal rather
  than adiabatic oscillations in the cold elements should be assumed
  in order to explain the observed fluctuations of line intensity; the
  relative amplitudes of pressure oscillations in the hot main component
  with a steep gradient of temperature are too small to explain the
  observed intensity fluctuations.

Title: The Atmosphere of a Sunspot Based on Observations in the
    X-Ray Extreme Ultraviolet Optical and Radio Ranges
Authors: Staude, J.; Furstenberg, F.; Hildebrandt, J.; Kruger,
   A.; Jakimiec, J.; Obridko, V. N.; Siarkowski, M.; Sylwester, B.;
   Sylwester, J.
Bibcode: 1984SvA....28..557S
Altcode:
  No abstract at ADS

Title: The atmosphere of a sunspot based on observations in the X-ray,
    extreme ultraviolet, optical, and radio ranges
Authors: Staude, J.; Furstenberg, F.; Hildebrandt, J.; Kruger,
   A.; Jakimiec, J.; Obridko, V. N.; Siarkowski, M.; Sylwester, B.;
   Sylwester, J.
Bibcode: 1984AZh....61..956S
Altcode:
  A model of the solar atmosphere above a sunspot umbra is developed on
  the basis of published X-ray, EUV, optical, and radio observations,
  summarizing the findings of working conferences held at Wroclaw in
  November-December 1979 (Bromboszcz et al. 1981) and at Ondrejov in
  September-October 1981 (Bromboszcz et al., 1982). A lower-chromosphere
  model like that of Teplitskaya et al. (1977 and 1978) is extended
  upward by applying a strong temperature gradient, with T = 40,000 K
  and n(e) = 4 x 10 to the 10th/cu cm at z = 2000 km above the umbral
  chromosphere. At z = 3000-5000 km, cool loops with T = (1-100) x 10
  to the 4th k are surrounded by hot (1.8 x 10 to the 6th K) coronal
  matter with a narrow transition layer and n(e) = 5 x 10 to the 8th/cu
  cm which occupies 0.8-0.9 of the total volume.

Title: A Model of the Oscillations in the Chromosphere and Transition
    Region above Sunspot Umbrae
Authors: Zhugzhda, Iu. D.; Staude, J.; Locans, V.
Bibcode: 1984SoPh...91..219Z
Altcode:
  In an earlier paper (Solar Phys.82, 369) the present authors proposed
  a model for the interpretation of velocity and intensity oscillations
  with periods between 2 and 3 minutes observed above umbrae. The model
  explains the oscillations by the resonant transmission of slow-mode
  magnetic-acoustic waves which are semi-trapped in a chromospheric
  cavity. In this way we get an independent method of checking
  semi-empirical models of umbral atmospheres.

Title: A Model of the Oscillations in the Chromosphere and Transition
    Region above Sunspot Umbrae
Authors: Zugzda, Y. D.; Staude, J.; Locans, V.
Bibcode: 1984AN....305..236Z
Altcode:
  No abstract at ADS

Title: Ein Modell der Oszillationen der Chromosphäre und
    Übergangsregioh über Sonnenfleckenumbrae
Authors: Žugžda, Y. D.; Staude, J.; Locans, V.
Bibcode: 1984AN....305Q.236Z
Altcode:
  No abstract at ADS

Title: A Model of the Oscillations in the Chromosphere and
Authors: Žugžda, Y. D.; Staude, J.; Locans, V.
Bibcode: 1984AN....305R.236Z
Altcode:
  No abstract at ADS

Title: A working model of sunspot structure in photosphere,
    chromosphere and corona, derived from X-ray, EUV, optical and radio
    observations
Authors: Staude, J.; Hildebrandt, J.; Fuerstenberg, F.; Krueger,
   A.; Jakimiec, J.; Obridko, V. N.; Siarkowski, M.; Sylwester, B.;
   Sylwester, J.
Bibcode: 1983AcA....33..441S
Altcode:
  The presented sunspot model consists of several parts which have been
  consistently put together: the umbral model describing the spatial
  distribution of thermodynamic quantities up to the transition region as
  derived from EUV and optical observations, the magnetic field model,
  the model of X-ray emission, and the S-component emission model. The
  model assumptions have been tested and corroborated by recently
  published observations with high spatial resolution obtained in the
  X-ray and EUV spectral range from Skylab, HRTS, and SMM, at centimeter
  wavelengths from RATAN, VLA, and WSRT, and by ground-based magnetograms.

Title: A Model of the Oscillations in the Chromosphere and Transition
    Region Above Sunspot Umbrae
Authors: Zhugzhda, Y. D.; Staude, J.; Locans, V.
Bibcode: 1983PDHO....5..451Z
Altcode: 1984PDHO....5..451Z
  In an earlier paper the authors proposed a model for the interpretation
  of velocity and intensity oscillations with periods between 2 and 3
  minutes observed above umbrae. The oscillations are explained by the
  resonant transmission of slow mode magneto-acoustic waves which are
  semi-trapped in a chromospheric cavity. The model has now been improved
  by more detailed calculations and corroborated by recently published
  observations: The calculations are in good agreement with (1) the
  height dependence of the observed phase difference between velocity
  and intensity oscillations, and with (2) the frequency spectrum of
  oscillations in the transition region above sunspots observed on the
  SMM spacecraft during the SMY.

Title: Results of vector magnetographic measurements in the active
    region SD 228/229 on 15 July 1982.
Authors: Bachmann, G.; Hofmann, A.; Staude, J.
Bibcode: 1983PDHO....5..369B
Altcode: 1984PDHO....5..369B
  The authors present measurements of vector magnetic fields in an active
  region of 15 July 1982 obtained with the new code-impulse magnetograph
  working in the wing of Fe I 5250 line. Linear polarization down to
  0.004 corresponding to transverse magnetic fields of about 150 G has
  been taken into account. The direction of the transverse magnetic
  fields is compared with dark chromospheric structure elements in Hα
  filtergrams and with the contours of sunspots obtained by means of
  a heliogram. For long-lived stable structures, such as the central
  part of the zero-line filament or systems of fibrils and threads,
  the correspondence is good, in contrast to short-lived. In regions
  with weak magnetic fields no correspondence is found.

Title: Seismology of Sunspot Atmospheres
Authors: Zhugzhda, Iu. D.; Locans, V.; Staude, J.
Bibcode: 1983SoPh...82..369Z
Altcode: 1983IAUCo..66..369Z
  The present work deals with the theory of oscillations with periods
  of about 3 min observed in the chromosphere above sunspot umbrae. The
  model of these oscillations (slow mode magneto-acoustic waves trapped
  in a chromospheric resonant cavity) provides an independent method of
  checking empirical models of the chromosphere above sunspots.

Title: Beobachtungen an neuen bipolaren Nebeln
Authors: Staude, J.; Neckel, Th.
Bibcode: 1983MitAG..60..322S
Altcode:
  No abstract at ADS

Title: A unified working model for the atmospheric structure of
    large sunspot umbrae
Authors: Staude, J.
Bibcode: 1981A&A...100..284S
Altcode:
  Horizontally averaged working models are derived for both the umbra
  of a large stable sunspot and the mean undisturbed environment
  for reference. It is noted that these models extend on a common
  geometrical height scale from subphotospheric layers to the base of
  the transition layer between chromosphere and corona; they are based
  on uniform and self-consistent physical assumptions for all layers
  and are able to explain the basic features of many observations at
  different wavelengths, including recent data from space. The present
  sunspot model furnishes the lower boundary condition for an attempt
  to model the transition layer and lower corona above large umbrae.

Title: Evidence for an X-Type Neutral Sheet Producing Chromospheric
    Activity
Authors: Seehafer, N.; Staude, J.
Bibcode: 1980SoPh...67..121S
Altcode:
  Force-free magnetic field extrapolation for region McMath 12417 on 4
  July 1973 corroborates a suggestion by Roy and Michalitsanos (1974):
  A large moving magnetic feature presses together opposite fluxes to
  form an X-type neutral sheet; the supposed geometry of the field as
  derived from chromospheric activity (subflares, ejections) is confirmed
  by the calculated lines of force.

Title: Problems concerning the calibration and interpretation of
    magnetograph observations in the solar photosphere and chromosphere
Authors: Staude, J.
Bibcode: 1980tpmb.meet...58S
Altcode:
  The paper presents procedures for the calibration of solar photoelectric
  magnetographs, which relate to the practical calibration of the
  primarily measured state of polarization in a magneto-sensitive line
  and to the theoretical derivation of magnetic field parameters from
  the polarization measurements. Disturbing influences are discussed
  including external disturbances such as stray light and instrumental
  polarization, saturation effects, and fine structures of the solar
  atmosphere, of velocity and magnetic fields. Problems in line formation
  theory are also discussed.

Title: Force-free Magnetic Field Extrapolation for the Complex
    Sunspot Group of August 1972
Authors: Seehafer, N.; Staude, J.
Bibcode: 1979AN....300..151S
Altcode:
  A method for theoretical extrapolation of photospheric longitudinal
  magnetograms to higher levels for force-free magnetic fields is
  presented. The method has been used to calculate the magnetic field
  vector and lines of force in the flare active region of August
  1972. Calculated fields are compared with other observations such
  as structures in H-alpha. Results of August 3 show that the loop
  prominence systems observed during the flares of August 2 and 4
  are represented by a force field with a positive value of alpha,
  rather than a current-free field. The extractable energy supply of
  this force-free field is of the order of maximum flare demand (10 to
  the 32nd erg); the height dependence of the magnetic field strengths
  agrees with that from radio and X-ray estimates. Similar results are
  obtained for the August 7 magnetic field structure. It is suggested
  that the mean magnetic field structure of the active region may be
  represented by a force-free field much better than by a potential field.

Title: Magnetfelder der Sonne und der Sterne. I.
Authors: Scholz, G.; Staude, J.
Bibcode: 1979Stern..55...65S
Altcode:
  No abstract at ADS

Title: Magnetfelder der Sonne und der Sterne. II.
Authors: Scholz, G.; Staude, J.
Bibcode: 1979Stern..55..206S
Altcode:
  No abstract at ADS

Title: Models of Heat Flux in the Subphotospheric Layers of Sunspots
    and the Interpretation of Umbral Granulation
Authors: Staude, J.
Bibcode: 1978BAICz..29...71S
Altcode:
  Different models of heat flux in the normal convective zone (deep and
  shallow reference models) and in an umbral flux tube in magnetostatic
  equilibrium are investigated by numerical calculations. Recent
  observations of umbral granulation are explained by residual cellular
  convection which still transfers a small fraction of energy to the
  subphotospheric flux tube. The models deduced from special assumptions
  concerning the reduced convective heat flux are also compatible
  with other recent observations such as superadiabatic temperature
  gradients in the deep umbral photosphere, and with results from
  nonlinear calculations considering effects of interaction between
  the magnetic field and turbulent convection. Some criteria for the
  inhibiting effect of the magnetic field on convection, derived from
  linear theories seem to be too strong.

Title: Influence of scintillation and scattering of light on
    magnetographic measurements.
Authors: Bachmann, G.; Staude, J.
Bibcode: 1977IzKry..56..148B
Altcode:
  No abstract at ADS

Title: Influence of the instrumental polarization on magnetographic
    observations.
Authors: Eger, F. W.; Staude, J.
Bibcode: 1977IzKry..56..149E
Altcode:
  No abstract at ADS

Title: Investigations in the field of magnetographic observations
    at the Einstein Solar Observatory in Potsdam.
Authors: Staude, J.
Bibcode: 1977IzKry..56R.205S
Altcode:
  No abstract at ADS

Title: Force-free magnetic field extrapolation for the complex
    sunspot group of August 1972.
Authors: Seehafer, N.; Staude, J.
Bibcode: 1977PDHO....3..137S
Altcode:
  No abstract at ADS

Title: Light Variations of AP Stars: 10-COLOUR Photometry and its
    Interpretation by a Magnetic SPOT Model
Authors: Schöneich, W.; Staude, J.
Bibcode: 1976paps.coll..387S
Altcode: 1976IAUCo..32..387S
  No abstract at ADS

Title: Models of the Solar Convective Zone: The Influence of Free
    Parameters in Mixing Length Theories
Authors: Staude, J.
Bibcode: 1976BAICz..27..365S
Altcode:
  Using Opik's (1950) mixing-length theory of convection, Mullan (1971)
  obtained extremely shallow models of the solar convection zone whose
  structure is incompatible with current conceptions of solar physics
  in general and with the deep models resulting from the Boehm-Vitense
  theory (1958) in particular. In the present paper, the Opik theory
  is generalized to take into account an anisotropy of small-scale
  turbulence; this version is then compared with the Boehm-Vitense
  theory. Neglecting a thin surface layer where radiative losses are
  important, a simple analytic comparison alone shows that both theories
  yield the same results, if the free parameters are chosen consistent
  with each other. To study the influence of the different parameters, a
  series of solar convection-zone models has been calculated numerically,
  assuming an empirical photospheric model as the upper boundary condition
  and various values of the parameters in both theories.

Title: Einige Methoden und Ergebnisse der modernen Sonnenforschung.
Authors: Staude, J.
Bibcode: 1976AsSch..13..101S
Altcode:
  No abstract at ADS

Title: Methodical improvements of magnetographic measurements
Authors: Bachmann, G.; Künzel, H.; Pflug, K.; Staude, J.
Bibcode: 1976CoSka...6..395B
Altcode:
  No abstract at ADS

Title: Model calculations concerning the subphotospheric layers of
    stable sunspots.
Authors: Staude, J.
Bibcode: 1976fsp..conf...63S
Altcode:
  No abstract at ADS

Title: Methodical improvement of magnetographic measurements.
Authors: Bachmann, G.; Künzel, H.; Pflug, K.; Staude, J.
Bibcode: 1976str..book..395B
Altcode:
  No abstract at ADS

Title: The Anomalous Splitting of the π-component of a ZEEMAN
    Triplet in Sunspot Umbrae and Suggestions for its Interpretation
Authors: Kuenzel, H.; Staude, J.
Bibcode: 1975AN....296..171K
Altcode:
  An investigation of the anomalous splitting of the pi-component
  of the line Fe I at 6302.5 A in umbrae is conducted, taking into
  account Zeeman spectrograms from 1200 sunspots of the maximum year
  1957. Disturbing effects are examined, giving attention to blends,
  stray light, and instrumental polarization. The observations appear to
  show a preponderance of left-hand screws of the magnetic field vector
  H in most umbrae independent of the polarity and the solar hemisphere.

Title: Mie- und Rayleigh-Streuung in der Erdatmosphäre
Authors: Staude, J.
Bibcode: 1974MitAG..35Q.267S
Altcode:
  No abstract at ADS

Title: Possibilities regarding the determination of the structure
    of solar magnetic fields outside the photosphere
Authors: Staude, J.
Bibcode: 1974ZMete..24..214S
Altcode:
  Physically well founded predictions of the solar activity and
  associated terrestrial effects require better, i.e. more detailed,
  knowledge of magnetic fields in the solar atmosphere, the chromosphere
  in particular. A critical review on methods of observing the solar
  magnetic fields is followed by a discussion of approaches of how to
  extrapolate, theoretically, into higher layers of the solar atmosphere
  the magnetic fields measured rather precisely in the photosphere. The
  force-free magnetic fields are given particular consideration;
  possibilities of testing by observations the theoretically calculated
  fields are described. Finally, the review contains proposals for
  further investigations.

Title: Die Frühjahrstagung in Garching.
Authors: Staude, J.
Bibcode: 1974S&W....13..111S
Altcode:
  No abstract at ADS

Title: On the interpretation of some peculiarities observed in
    zeeman-split line contours in sunspots
Authors: Staude, Jürgen
Bibcode: 1973SoPh...32..403S
Altcode:
  Strong line wings and the V-reversal in umbral countours of Fe I 6302.5
  Å and similar lines have been explained earlier by inhomogeneous
  magnetic models. It is shown that both effects may also be explained
  assuming a homogeneous magnetic field and homogeneous umbral model
  atmospheres.

Title: Non-LTE Line Formation in a Magnetic Field. II: The Influence
    of Non-Coherent Scattering on Line Contours
Authors: Domke, H.; Staude, J.
Bibcode: 1973SoPh...31..291D
Altcode:
  Theoretical line contours calculated for fixed values of the line
  constants and a given model atmosphere show an increase of the
  Stokes parameters Q, U, and V but a decrease of I if the portion of
  non-coherent scattering increases. These effects increase from the
  centre of the solar disk to the limb. The action of scattering may be
  approximately simulated in LTE contours by increasing the gradient
  of the source function and fitting in this way theoretical contours
  to observed ones. There remains, however, the effect of V-reversal
  near the line core, which is caused by anomalous dispersion and is
  abnormally increased by scattering.

Title: Non-LTE Line Formation in a Magnetic Field. I: Non-Coherent
    Scattering and True Absorption
Authors: Domke, H.; Staude, J.
Bibcode: 1973SoPh...31..279D
Altcode:
  The formation of a Zeeman-multiplet by noncoherent scattering and true
  absorption in a Milne-Eddington atmosphere is considered assuming a
  homogeneous magnetic field and complete depolarization of the atomic
  line levels. The transfer equation for the Stokes parameters is
  transformed into a scalar integral equation of the Wiener-Hopf type
  which is solved by Sobolev's method in closed form. The influence of
  the magnetic field on the mean scattering number in an infinite medium
  is discussed.

Title: Flächenpolarimetrie der südlichen Milchstraße
Authors: Staude, J.; Wolf, K.; Schmidt, Th.
Bibcode: 1973MitAG..34...95S
Altcode:
  No abstract at ADS

Title: A Surface Polarization Survey of the Milky way and the Zodiacal
    Light (presented by th. Schmidt)
Authors: Staude, J.; Wolf, K.; Schmidt, Th.
Bibcode: 1973IAUS...52..139S
Altcode:
  No abstract at ADS

Title: About the influence of a magnetic field on the model atmosphere
    of a magnetic star.
Authors: Staude, J.
Bibcode: 1973AN....294..113S
Altcode:
  No abstract at ADS

Title: About the Influence of a Magnetic Field on the Model Atmosphere
    of a Magnetic Star
Authors: Staude, J.
Bibcode: 1972AN....294..113S
Altcode:
  No abstract at ADS

Title: Circular Polarisation Measurements of the Zodiacal Light
Authors: Staude, J.; Schmidt, Th.
Bibcode: 1972A&A....20..163S
Altcode:
  Key words: circular polarisation - zodiacal light Summary. The circular
  polarisation component of the zodiacal light is shown to be zero within
  the accuracy of l 10/00 (p. p. thousands).

Title: On the Mean Depth of Line Formation in a Magnetic Field
Authors: Staude, Jürgen
Bibcode: 1972SoPh...24..255S
Altcode:
  Probability interpretation of radiative transfer is used to calculate
  the contribution of different layers of the solar atmosphere to the
  emergent intensity. Generally the mean depths of line formation increase
  with increasing intensity; this is valid also for arbitrarily polarized
  constituents of a line formed in a magnetic field.

Title: Flächenpolarimetrie des südlichen Gesamthimmels
Authors: Wolf, K.; Staude, J.
Bibcode: 1972MitAG..31..167W
Altcode:
  No abstract at ADS

Title: Einige Methoden und Ergebnisse der modernen Sonnenforschung.
Authors: Staude, J.
Bibcode: 1972AsSch...9...90S
Altcode:
  No abstract at ADS

Title: A Generalized Analytic Solution to the Equations of Transfer
    in a Magnetic Field
Authors: Staude, Jürgen
Bibcode: 1971SoPh...18...22S
Altcode:
  No abstract at ADS

Title: Remarks on Some Recent Papers Concerning Line Formation in
    a Magnetic Field
Authors: Staude, Jürgen
Bibcode: 1971SoPh...18...24S
Altcode:
  No abstract at ADS

Title: On apparent differences in magnetic field strengths measured
    from Zeeman splittings of molecular lines and Fe  i λ 5250.2 Å
Authors: Staude, Jürgen
Bibcode: 1971SoPh...17..331S
Altcode:
  No abstract at ADS

Title: Line Formation in a Magnetic Field and the Interpretation of
Magnetographic Measurements. III: Calculations for Different Spot
    Models and Arbitrary Depth Dependence of the Magnetic Field Vector
Authors: Staude, J.
Bibcode: 1970SoPh...15..102S
Altcode:
  The strong temperature dependence of the line FeIλ 5250.2 Ā has been
  studied by calculating line contours and magnetographic calibration
  curves for different spot models and the BCA. Line contours calculated
  for arbitrary depth dependence of the magnetic field vector show
  depolarization effects within the Zeeman components for transversal
  fields with variable direction and changes of the observed plane of
  polarization if anomalous dispersion is taken into account.

Title: Europium and Lanthanum in Sunspot and in the Undisturbed
    Photosphere
Authors: Bachmann, G.; Pflug, K.; Staude, J.
Bibcode: 1970SoPh...15..113B
Altcode:
  Line profiles of EUIIλ4129.7 Å and LaIIλ4086.7 Å were observed
  photoelectrically and photographically in the photosphere and
  within sunspots and after correction were compared with calculated
  profiles. The observed large hyperfine structure broadening and
  isotope shift of λ4129.7 Å confirm the Eu origin of this line and
  suggest a larger Eu abundance than that recently published by Grevesse
  and Blanquet (1969). The line profiles within the spot may be well
  represented by means of the spot model of Hénoux (1969), while older
  spot models are not able to do it. An abundance difference between
  spot and photosphere has not been observed.

Title: Line Formation in a Magnetic Field and the Interpretation of
Magnetographic Measurements. II: The Influence of Different Atmosphere
    Models and of a Magnetic Field Gradient
Authors: Staude, J.
Bibcode: 1970SoPh...12...84S
Altcode:
  The solution of the equations of transfer for the Stokes parameters
  in a magnetic field given by Unno (1956) has been generalized for a
  non-linear source function. Model calculations have been carried out
  for empiric atmosphere models of the photosphere and spots both for
  homogeneous magnetic fields and for a field strength gradient. Their
  influence on line contours and magnetographic calibration curves had
  been studied for the line FeI λ5250.2 Å.

Title: About the Influence of Inhomogeneities of Magnetic Fields on
    Line Contours and Magnetographic Measurements
Authors: Staude, J.
Bibcode: 1969SoPh....8..264S
Altcode:
  The discrepancies between theoretical and experimental calibration
  curves for solar magnetographs (Severny, 1967) may be explained by
  horizontal inhomogeneities of the observed but not resolved magnetic
  field region. Using the Unno solution of the equations of transfer
  simple two-stream models have been constructed. For the more complicated
  case of a depth dependence of the magnetic field vector it is shown
  assuming pure absorption and permitting arbitrary variations of the
  magnetic field vector and the atmosphere model with depth that a
  solution of the equations of transfer may be found by iteration.

Title: Influence of inhomogeneities of magnetic fields on line
    contours and magnetographic measurements.
Authors: Staude, J.
Bibcode: 1969VeGG...13..123S
Altcode:
  No abstract at ADS

