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Author name code: wiehr
ADS astronomy entries on 2022-09-14
author:"Wiehr, Eberhard" 

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Title: Velocity Difference of Ions and Neutrals in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H.; Bianda, M.
2021ApJ...920...47W    Altcode: 2021arXiv210813103W
  Marked velocity excesses of ions relative to neutrals are obtained
  from two time series of the neighboring emission lines He I 5015
  Å and Fe II 5018 Å in a quiescent prominence. Their Doppler
  shifts show time variations of quasi-periodic character where the
  ions are faster than the neutrals, 1.0 ≤ V<SUB>macro</SUB>(Fe
  II)/V<SUB>macro</SUB>(He I) ≤ 1.35 in series A and ≤1.25 in
  series B. This "ratio excess" confirms our earlier findings of a 1.22
  ion velocity excess, but the present study shows a restriction in
  space and time of typically 5 Mm and 5 minutes. The ratio excess is
  superposed by a time- and velocity-independent "difference excess"
  of -0.3 ≤ V<SUB>macro</SUB>(Fe II)-V<SUB>macro</SUB>(He I) ≤
  +0.7 km s<SUP>-1</SUP> in series A (also indicated in series B). The
  high repetition rate of 3.9 s enables the detection of high-frequency
  oscillations with several damped 22 s periods in series A. These show
  a ratio excess with a maximum of 1.7. We confirm the absence of a
  significant phase delay of He neutrals with respect to the Fe ions.

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Title: Evidence for the Two-fluid Scenario in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Bianda, M.
2019ApJ...873..125W    Altcode: 2019arXiv190401536W
  This paper presents observational evidence of the different dynamical
  behavior of neutral and ionized species in solar prominences. The
  analysis of a time-series of Sr II 4078 Å and Na D spectra in a
  quiescent prominence yields systematically larger Doppler shifts
  (line-of-sight velocities) for the ions V <SUB>LOS</SUB>(Sr II) = 1.22
  × V <SUB>LOS</SUB>(Na D). Both lines show a 30 minute oscillation of
  good coherence. Sixteen hours later the same prominence underwent marked
  morphological changes (with a rising dome), and the Sr II velocity
  excess dropped to V <SUB>LOS</SUB>(Sr II) = 1.11 ×V <SUB>LOS</SUB>(Na
  D). The same excess is found for the line pair Fe II 5018 Å and He I
  5015 Å. The widths of the ionic lines, mainly non-thermally broadened,
  are not related to the macro-velocities. The emission ratio of Na D
  and Sr II, a measure of the electron density, yields n <SUB>e</SUB>
  = 4 × 10<SUP>10</SUP> cm<SUP>-3</SUP>, shows no relation with the V
  <SUB>LOS</SUB> variation or with height above the limb, and seems to be
  reduced 16 hr later during the active phase. We apply a new wavelength
  reference from aureola spectra, which is independent of photospheric
  velocity fields.

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Title: The Na I and Sr II Resonance Lines in Solar Prominences
Authors: Stellmacher, G.; Wiehr, E.
2017SoPh..292...83S    Altcode: 2017arXiv170502475S
  We estimate the electron density, n<SUB>e</SUB>, and its spatial
  variation in quiescent prominences from the observed emission ratio
  of the resonance lines Na I 5890 Å (D<SUB>2</SUB>) and Sr II 4078
  Å. For a bright prominence (τ<SUB>α</SUB>≈25 ) we obtain
  a mean n<SUB>e</SUB>≈2 ×10<SUP>10</SUP>cm−<SUP>3</SUP>;
  for a faint one (τ<SUB>α</SUB>≈4 ) n<SUB>e</SUB>≈4
  ×10<SUP>10</SUP>cm−<SUP>3</SUP> on two consecutive days with
  moderate internal fluctuation and no systematic variation with height
  above the solar limb. The thermal and non-thermal contributions to
  the line broadening, T<SUB>kin</SUB> and V<SUB>nth</SUB>, required
  to deduce n<SUB>e</SUB> from the emission ratio Na I/Sr II cannot be
  unambiguously determined from observed widths of lines from atoms of
  different mass. The reduced widths, Δ λ<SUB>D</SUB>/λ<SUB>0</SUB>,
  of Sr II 4078 Å show an excess over those from Na D<SUB>2</SUB> and
  Hδ 4101 Å, assuming the same T<SUB>kin</SUB> and V<SUB>nth</SUB>. We
  attribute this excess broadening to higher non-thermal broadening
  induced by interaction of ions with the prominence magnetic field. This
  is suggested by the finding of higher macro-shifts of Sr II 4078 Å
  as compared to those from Na D<SUB>2</SUB>.

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Title: The Electron Density in a Quiescent Prominence
Authors: Wiehr, E.; Stellmacher, G.; Bianda, M.
2016CEAB...40...79W    Altcode:
  We estimate the electron density, n_e, from the emission ratio of the
  Na I D_2 and Sr II 4078 Å resonance lines. For a quiescent prominence,
  we find a range 1.7≤ n_e≤3.4\cdot 10^{10}cm^{-3} with significant
  differences between neighboring structures but not with height above
  the solar limb. After seven hours of moderate evolutionary changes,
  the prominence shows the same n_e range.

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Title: Non-thermal line-broadening in solar prominences
Authors: Stellmacher, G.; Wiehr, E.
2015A&A...581A.141S    Altcode: 2016arXiv160507923S
  <BR /> Aims: We show that the line broadening in quiescent solar
  prominences is mainly due to non-thermal velocities. <BR /> Methods:
  We have simultaneously observed a wide range of optically thin lines
  in quiescent prominences, selected for bright and narrow Mg b emission
  without line satellites from macro-shifts. <BR /> Results: We find a
  ratio of reduced widths, Δλ<SUB>D</SUB>/λ<SUB>0</SUB>, of Hγ and Hδ
  of 1.05 ± 0.03, which can hardly be attributed to saturation, since
  both are optically thin for the prominences observed: τ<SUB>γ</SUB>
  ≤ 0.3, τ<SUB>δ</SUB> ≤ 0.15. We confirm the ratio of reduced
  widths of He 4772 (triplet) and He 5015 (singlet) of 1.1 ± 0.05 at
  higher significance and detect a width ratio of Mg b<SUB>2</SUB>
  and Mg 4571 (both from the triplet system) of 1.3 ± 0.1. <BR />
  Conclusions: The discrepant widths of lines from different atoms,
  and even from the same atom, cannot be represented by a unique pair
  [T<SUB>kin</SUB>; V<SUB>nth</SUB>]. Values of T<SUB>kin</SUB> deduced
  from observed line radiances using models indicate low temperatures
  down to T<SUB>kin</SUB> ≈ 5000 K. Non-thermal velocities, related to
  different physical states of the respective emitting prominence region,
  seem to be the most important line broadening mechanism.

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Title: The Temperature of Quiescent Prominences
Authors: Wiehr, E.; Stellmacher, G.
2015CEAB...39...35W    Altcode:
  We simultaneously observed in solar prominences faint metallic
  emission lines together with Hγand two He I lines from the singlet
  and triplet systems, respectively. We find that the reduced widths
  Δλ<SUB>D</SUB>/λ<SUB>0</SUB> are not linearly related to the
  square-root of the inverse atomic mass, as is expected from the Doppler
  formula. Instead, each emission line is individually broadened. The
  gradients in the V<SUB>D</SUB><SUP>2</SUP>(1/μ) diagrams correspond
  to unrealistically high T<SUB>kin</SUB>≥10<SUP>4</SUP> K, which
  contradict values deduced from line radiance observations yielding
  temperatures down to at most 5000 K. A scenario of down-falling gas
  clumps by Low et al. (2012) offers a plausible explanation for these
  discrepancies.

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Title: The Hot Skin of Prominence Structures
Authors: Wiehr, E.; Stellmacher, G.; Ramelli, R.; Bianda, M.
2013CEAB...37..487W    Altcode:
  We observe various emission lines in solar prominences and compare
  the widths of He II 4686 Å, He I 4472 Å (triplet) and He I 5015 Å
  (singlet) with those of the optically thin Hγ and Mg b_2 lines. The
  latter two yield a thermal line broadening of 9000&lt;T_{kin}&lt;11
  000 K, which fits the width of He I 5015 Å (singlet). However, He I
  4471 Å (triplet) shows an excess of 1.1 indicating an excitation of
  the triplet in 1.2 times hotter prominence regions. He II 4686 Å is
  1.65 times broader and thus emitted in 2.73 times hotter regions of the
  prominence-corona transition layer, PCTR. The linear radiance relations
  He tripl/He II=50 and Hγ/He tripl=11.8 suggest a PCTR between each
  fine-structure thread and the surrounding hot coronal gas.

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Title: Helium Emissions Observed in Ground-Based Spectra of Solar
    Prominences
Authors: Ramelli, R.; Stellmacher, G.; Wiehr, E.; Bianda, M.
2012SoPh..281..697R    Altcode: 2012SoPh..tmp..221R; 2012arXiv1208.2153R
  The only prominent line of singly ionized helium in the visible
  spectral range, He II 4686 Å, is observed together with the He I 5015
  Å singlet and the He I 4471 Å triplet line in solar prominences. The
  Na D<SUB>2</SUB> emission is used as a tracer for He II emissions which
  are sufficiently bright to exceed the noise level near 10<SUP>−6</SUP>
  of the disk-center intensity. The prominences thus selected are
  characterized by small non-thermal line broadening and almost absent
  velocity shifts, yielding narrow line profiles without wiggles. The
  reduced widths [Δλ<SUB>D</SUB>/λ] of He II 4686 Å are 1.5 times
  broader than those of the He I 4471 Å triplet and 1.65 times broader
  than those of the He I 5015 Å singlet. This indicates that the He
  lines originate in a prominence-corona transition region with outwards
  increasing temperature.

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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.
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.

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Title: The Spatial Structure of the Evershed effect
Authors: Wiehr, E.
2012arXiv1210.2553W    Altcode:
  The line profile asymmetry defining the Evershed effect in sunspot
  penumbrae, disappears abruptly at the outer sunspot boundary over a
  horizontal distance of less than 500 km immediately at the outermost
  ends of the dark penumbral continuum structures ('filaments'). This
  is indicated from the non-magnetic lines Ni I 5435.9 (g=0.5) and Fe
  I 5434.5 (g=0), which loose their profile asymmetries at the same
  spatial location although formed at a vertical height distance of 300
  km. The widely accepted 'canopy' picture conflicts with this finding
  which, in contrary, suggests that the gas motion associated with
  the Evershed effect disappears together with the continuum intensity
  drop at the outer sunspot (penumbral) border. Corresponding downflows
  must then be smaller than the spatial resolution presently achieved
  (i.e., &lt;0.5 arcsec) and located at the immediate outer sunspot
  border. It is suggested that this location marks the sharp threshold
  of the equipartition between kinetic and magnetic energy density at
  the outer penumbral boundary.

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Title: The Area Coverage of Small-scale Solar Magnetic Structures
    in a Quiet Region
Authors: Wiehr, E.; Bovelet, B.
2009CEAB...33...19W    Altcode:
  Inter-granular structures, IgS, are segmented with the `multiple-level
  tracking' pattern recognition algorithm, MLT 4 in a 149 ” x 117 ”
  G-band image taken at disc centre of the non-active Sun. From the total
  of 7593 IgS, the non-magnetic ones are identified in the scatterplot of
  continuum and G-band brightness which is known to show a magnetic and a
  non-magnetic branch. The overlap regime of both is largely disentangled
  applying an intrinsic Ca II H contrast criterion. <P />For the thus
  obtained 2995 magnetic IgS, the MIgS, we obtain a number density of 0.32
  MIgS/Mm^2. Their sizes, provided by MLT 4 in pixel counts independent
  of the shape, yield a total area contribution of 2.0%. Superimposing
  the MIgS to the simultaneously observed Hα image, we find a preferred
  location at the foot points of the dark fibrils, which are known to
  mark the network boundaries. A substantial amount of the MIgS is,
  however, located in the fibril voids, and thus in the inter-network.

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Title: Balmer and Lyman Emission Lines in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.
2009CEAB...33...99W    Altcode:
  Space observations of Lyman lines are compared with ground-based
  observations of Balmer lines for quiescent solar prominences of
  comparable brightness defined by their Hβ emission. The integrated
  spectral line radiances of the Lyman and the Balmer emissions show
  differences which diminish with increasing upper level u and converge
  toward highest level numbers. Lyman lines emitted from u=5 originate
  from 250 times less emitters than the corresponding Balmer lines from
  the same upper level. For u=8 this difference still amounts to a factor
  of 65, supporting the idea of a distinct origin of the emissions of
  both hydrogen series.

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Title: On the origin of the Balmer and Lyman emission lines in
    solar prominences
Authors: Stellmacher, G.; Wiehr, E.
2008A&A...489..773S    Altcode: 2012arXiv1209.6264S
  Aims: We show how the observed hydrogen Balmer and Lyman emission lines
  constrain the modeling of quiescent solar prominences. <BR />Methods:
  We compare space observations of Lyman lines with ground-based
  observations of Balmer lines for quiescent solar prominences of
  comparable brightness defined by their Hβ emission. <BR />Results:
  The effective number densities of hydrogen atoms emitting from the
  same upper level u deduced from the corresponding emerging Lyman
  and Balmer line emissions show large differences that diminish
  with increasing level number and converge at the highest level
  numbers. Hydrogen atoms excited in u=5 contribute 250 times less,
  and those in u=8 still contribute 65 times less to the Lyman than to
  the corresponding Balmer emission, supporting the idea of distinct
  spatial origin of the emissions of both series. This is also indicated
  by the line widths. The high optical thickness of all Lyman members
  allows the brightness temperature T<SUB>b</SUB> to be estimated from
  the spectral radiance at line center, where T<SUB>b</SUB> is found to
  be largely independent of the upper level number, in contrast to the
  (known) behavior of the Balmer lines.

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Title: The quiet Sun's magnetic flux estimated from Ca II H bright
    inter-granular G-band structures
Authors: Bovelet, B.; Wiehr, E.
2008A&A...488.1101B    Altcode: 2012arXiv1208.2160B
  Aims: We determine the number density and area contribution of
  small-scale inter-granular Ca II bright G-band structures in images of
  the quiet Sun as tracers of kilo-Gauss magnetic flux-concentrations. <BR
  />Methods: In a 149 arcsec × 117 arcsec G-band image of the disk center
  at the activity minimum, 7593 small inter-granular structures were
  segmented with the “multiple-level tracking” pattern recognition
  algorithm. The scatterplot of the continuum versus the G-band brightness
  shows the known magnetic and non-magnetic branches. These branches
  are largely disentangled by applying an intrinsic Ca II H excess
  criterion. The thus obtained 2995 structures contain 1152 G-band bright
  points (BP) and 1843 G-band faint points (FP). They show a tendency
  toward increasing size with decreasing G-band excess, as expected
  from the “hot wall” picture. Their Ca II H and G-band brightness
  are slightly related, resembling the known relation of Ca II and
  magnetic field strength. The magnetic flux density of each individual
  BP and FP is estimated from their G-band brightness according to MHD
  model calculations. <BR />Results: The entity of BP and FP covers
  the total FOV with a number density of 0.32 / Mm<SUP>2</SUP> and a
  total area contribution of 2.0%. Their individual calibrations yield
  a mean flux density of 20 Mx/cm<SUP>2</SUP> in the entire FOV and 13
  Mx/cm<SUP>2</SUP> for inter-network regions.

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Title: Multiple-Scale Pattern Recognition Applied to Faint
    Intergranular G-band Structures
Authors: Bovelet, B.; Wiehr, E.
2007SoPh..243..121B    Altcode:
  Small-scale solar magnetic flux concentrations are studied in
  two-dimensional G-band images at very high spatial resolution and
  compared with Ca II H enhancements. Among 970 small-sized G-band
  intergranular structures (IgS), 45% are co-spatial with isolated
  locations of Ca II H excess and thus considered as magnetic (MIgS);
  they may be even twice as frequent as the known G-band bright
  points. The IgS are recognized in the G-band image by a new algorithm
  operating in four steps: (1) A set of equidistant detection levels
  yields a pattern of primary "cells"; (2) for each cell, the intrinsic
  intensity profile is normalized to its brightest pixel; (3) the cell
  sizes are shrunk by a unitary single-intensity clip; (4) features in
  contact at an appropriate reference level are merged by removal of the
  respective common dividing lines. Optionally, adjoining structures may
  be excluded from this merging process (e.g., chains of segmented IgS),
  referring to the parameterized number and intensity of those pixels
  where enveloping feature contours overlap. From the thus recognized
  IgS pattern, MIgS are then selected by their local Ca II H contrast
  and their mean G-band-to-continuum brightness ratio.

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Title: Imaging of the He D<SUB>3</SUB>/Hβ Emission Ratio in Quiescent
    Solar Prominences
Authors: Hirzberger, J.; Wiehr, E.; Stellmacher, G.
2007ASPC..368..321H    Altcode:
  Quiescent solar prominences have been observed simultaneously in
  profile-integrated He D<SUB>3</SUB> and Hβ emission with the SST on
  La Palma. The two-dimensional ratio maps of the He D<SUB>3</SUB> and
  Hβ intensities are used to study temporal variations of intrinsic
  prominence parameters. Sub-areas with substantial variation of
  the intensity distribution indicate the evolution of prominence
  structures. When the emission ratio remains unchanged, the evolving
  threads are of largely equal physical state. Other regions which show
  a temporal varying emission ratio indicate substancial evolution of
  the intrinsic physical conditions. We propose that distance variation
  between the threads affects different penetration of the EUV irradiation
  required for populating of the He triplet system.

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Title: Two-dimensional imaging of the He D_3/Hbeta emission ratio
    in quiescent solar prominences .
Authors: Stellmacher, G.; Wiehr, E.; Hirzberger, J.
2007MmSAI..78..108S    Altcode:
  Simultaneous prominences spectroscopy with THEMIS in the emission
  lines H-alpha, H-beta, HeD3, NaD2, Mgb2 and He(singlet)5015 lead to
  an extended study of two-dimensional images simultaneously in H-beta
  and HeD3. The spatial variation of the integrated line intensities and
  their ratio shows mainly two characteristics: (a) A constant emission
  ratio (even) in regions with substantial intensity variations; this
  can be explained by a varying number of superposing threads with equal
  physical states. (b) A varying emission ratio (often) tightly related
  to intensity changes; this indicates a superposition of threads with
  different physical states (most likely the gas-pressure). We also
  observe temporal changes of the emission ratio which seem to be too
  fast for a variation of the gas-pressure; here, we suppose a change of
  the packing density of threads along the line-of-sight which affects
  the penetration of ionizing UV radiation required for the He triplet
  excitation.

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Title: Two-Dimensional Mapping of the He D<SUB>3</SUB>/Hβ Emission
    Ratio in Solar Prominences
Authors: Wiehr, Eberhard; Stellmacher, Goetz; Hirzberger, Johann
2007SoPh..240...25W    Altcode:
  Solar prominences have been simultaneously observed in the integrated
  light of the He D<SUB>3</SUB> and the Hβ emissions on two successive
  days, using the SST on La Palma with its tip-tilt mirror locked on a
  nearby white-light limb facular grain. The spatial and the temporal
  variation of the integrated line intensities and their ratio shows
  mainly two characteristics: (A) Constant emission ratio (even)
  in regions with substantial intensity variations and (B) varying
  emission ratio (often) tightly related to intensity structures of the
  prominence. (A) May be explained by a different number of superposing
  threads along the line of sight having very similar physical state. (B)
  Indicates threads with different intrinsic physical states; these
  may depend on the gas pressure or the inner structure of each thread,
  i.e., the "packing density," affecting the penetration of ionizing EUV
  radiation, which affects the He I level populations and thus the rate
  of the triplet excitation.

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Title: Two-dimensional imaging of the HeD3/H[Beta] emission ratio
    in quiescent solar prominences
Authors: Wiehr, E.; Stellmacher, G.; Hirzberger, J.
2007msfa.conf..261W    Altcode:
  We extend our earlier studies of two-dimensional prominence imaging
  by simultaneous observations of the HeD3 and H[Beta] emissions at
  the 1m SST on La Palma. The observed small spatial variations of the
  HeD3/H[Beta] ratio indicate rather homogeneous physical conditions
  within prominences. Sub-regions do exist which show a largely uniform
  ratio in spite of substantial spatial intensity variations. Here, the
  fine-structures will exhibit almost uniform physical conditions. In
  other regions with variations of the ratio parallel to the emissions,
  the structures will have different intrinsic physical state.

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Title: Influence of the magnetic field on the velocity of the high
    frequency waves in the solar chromosphere
Authors: Andjic, A.; Wiehr, E.
2006POBeo..80..367A    Altcode:
  High frequency acoustic waves are thought to be the source of the
  mechanical heating of the chromosphere. The observed velocity interval
  of high frequency wave propagation starts with 3.7± 0.4 km/s but the
  upper limit cannot be observed with the temporal resolution achieved
  in this work. Three areas of the Sun with the various activities are
  observed. Only events with the amplitudes larger than 50% of the maximum
  one were analysed in this work. The magnetic field has an influence on
  the propagation of high frequency waves. In the quiet Sun area only 49%
  of the observed events are connected with the magnetic field, while in
  areas with the magnetic structures 70% of the observed wave features
  are connected with the magnetic field.

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Title: The flux-gap between bright and dark solar magnetic structures
Authors: Puschmann, K. G.; Wiehr, E.
2006A&A...445..337P    Altcode:
  The upper size limit of solar small-scale magnetic flux concentrations
  ("G-band bright points", BP) is reconsidered from speckle-reconstructed
  images taken at the 1-m SST on La Palma. The size-histogram shows
  a sharp drop towards 250 km diameter, variation of the noise filter
  threshold diminishes that value due to segmentation of the elongated
  structures. A further artificial segmentation of still elongated
  (i.e. not round) BP indicates that the upper limit may well be below 200
  km diameter, corresponding to a flux smaller than 2.5×10<SUP>17</SUP>
  Mx which is more than 40 times smaller than that of smallest dark
  (mini-) pores. BP with diameters of 130 km would already yield to a
  flux gap of two orders of magnitude. The drop of BP numbers between the
  histogram maximum and the 90 km resolution limit achieved is found to
  depend on the low-pass filtering and is thus probably virtual. Higher
  spatial resolution data will still increase the flux gap between bright
  and dark solar magnetic flux concentrations which might be a signature
  of differently deep rooting in the solar atmosphere.

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Title: The Size of Small-Scale Solar Magnetic Regions
Authors: Wiehr, E.; Puschmann, K. G.
2005ESASP.596E..20W    Altcode: 2005ccmf.confE..20W
  No abstract at ADS

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Title: Spectropolarimetry of a sunspot at disk centre
Authors: Sánchez Cuberes, M.; Puschmann, K. G.; Wiehr, E.
2005A&A...440..345S    Altcode:
  The magnetic, thermal and velocity structure of a sunspot at
  the solar disk centre (θ=2°) is investigated by inverting the
  full Stokes profiles of three infrared lines. A single magnetic
  component atmosphere is assumed with height gradients of the physical
  quantities. Since the line-of-sight (LOS) is perpendicular to the solar
  surface, differential optical or projection effects do not interfere,
  as often is the case for the usual observations at oblique LOS. We find
  a symmetric configuration of the field and flow and the downward motion
  that increases with radial distance by up to 3 km s<SUP>-1</SUP> near
  the outer penumbral border. The magnetic field is found to be highly
  axially symmetric without any indication of azimuthal vortices. A
  tight relation between field strength and inclination is obtained
  with a gradient of 35°/1000 G independent of height. The penumbra
  shows "spines" hosting a pronounced negative correlation between
  field strength and inclination in the sense that steeper and stronger
  magnetic fields are related to brightenings in the line cores but not
  in the continuum. We discuss the dependence of the obtained results
  on different assumptions of parasitic light, and present indications
  of its overestimation by the inversion code.

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Title: Solar limb faculae
Authors: Hirzberger, J.; Wiehr, E.
2005A&A...438.1059H    Altcode:
  We observe solar limb faculae at an unprecedented spatial
  resolution with the new 1 m Swedish Solar Telescope SST on La
  Palma. Speckle-reconstructed images are used to study 4475 limb
  facular grains simultaneously in the 430 nm G-band and the 587.5±1.5
  continuum up to only 1” from the limb (cos θ=0.05). No systematic
  contrast decrease is found even a few arcsec from the solar limb. The
  facular grains appear to be “projected” on the limb-side neighboring
  granules; approaching the disc center, the corresponding features occur
  as inter-granular G-band bright points. Independently, we took spectra
  with the French-Italian THEMIS telescope on Tenerife and find that
  the known “line-gap effect” from disc center disappears near the
  limb. Here, the facular continuum is enhanced whereas the normalized
  profiles are unchanged with respect to the undisturbed neighborhood.

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Title: Solar prominences with Na and Mg emissions and centrally
    reversed Balmer lines
Authors: Stellmacher, G.; Wiehr, E.
2005A&A...431.1069S    Altcode: 2012arXiv1210.5643S
  We observed bright solar limb prominences with significant emission
  of NaD2 and Mgb2 simultaneously with the Hα, Hβ, HeD3, He^+4685,
  and the He^singl 5015 Å lines, using the THEMIS telescope on
  Tenerife. We find that most prominences with significant NaD2 and
  Mgb2 emissions show pronounced centrally reversed Hα profiles, and
  occasionally even of Hβ; the strongest emissions reach integrated
  intensities Eβ&gt;16×{}10<SUP>4</SUP> [ erg/(cm<SUP>2</SUP> s str)]
  . The centrally reversed profiles are well reproduced by semi-infinite
  models. The source function reaches Sα≤{}36 × {}10<SUP>4</SUP>
  [ erg/(cm<SUP>2</SUP> s str Å)] corresponding to an excitation
  temperature T_ex<SUP>α</SUP>≈3950 K; here, the optically thickness of
  Hα amounts τ^0<SUB>α</SUB>≈{}10. The line widths of the NaD2, Mgb2,
  and HeD3 profiles yield kinetic temperatures 7000≤{}T_kin&lt;8000
  K and non-thermal broadening v_tu=5 km s<SUP>-1</SUP>.

---------------------------------------------------------
Title: Brightness and size of small-scale solar magnetic flux
    concentrations
Authors: Wiehr, E.; Bovelet, B.; Hirzberger, J.
2004A&A...422L..63W    Altcode:
  The new 1 m Swedish Solar Telescope SST on La Palma allows to observe
  inter-granular G-band bright points (igBP) in solar active regions at
  an unprecedented spatial resolution. The igBP are reasonably assumed
  to be small-scale magnetic flux-concentrations. A sample of more than
  1500 igBP shows tight relations of diameter and brightness in the
  G-band and in the continuum; it covers a diameter range of 100 km to
  300 km, with a most frequent value near 160 km. Features larger than
  300 km formerly reported, evidently result from insufficient spatial
  resolution; that upper diameter limit is close to the typical width
  of inter-granular lanes, and suggests a “gap” to small pores. The
  lack of igBP with sizes below 130 km is discussed not to arise from
  the finite spatial resolution of the 1 m telescope.

---------------------------------------------------------
Title: Riesenkonvektion unter Sonnenflecken
Authors: Wiehr, Eberhard; Bovelet, Burkart
2004S&W....43d..22W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Observational Aspects of Doppler Oscillations in Solar
    Prominences
Authors: Wiehr, E.
2004ESASP.547..185W    Altcode: 2004soho...13..185W
  No abstract at ADS

---------------------------------------------------------
Title: Polarimetry of a sunspot at disk centre
Authors: Sánchez Cuberes, M.; Puschmann, K. G.; Wiehr, E.
2004IAUS..223..237S    Altcode: 2005IAUS..223..237S
  No abstract at ADS

---------------------------------------------------------
Title: Dynamics of the solar active region finestructure
Authors: Bovelet, B.; Wiehr, E.
2003A&A...412..249B    Altcode:
  We investigate the dynamical behavior of the finestructure in a
  sunspot's surroundings and its penumbra from a speckle-reconstructed
  60 min time series taken at the 45 cm Dutch Open Telescope (DOT)
  on La Palma. In the 1 nm spectral window containing the G-band, we
  determine the area of each feature and its time evolution by means of
  pattern recognition, particularly adapted to separate bright granular
  edges from inter-granular G-band bright points (BP). The evolution of
  each individual BP shows a stronger variation of the area than of the
  intensity. We analyze the horizontal motions of BP as a function of
  their distance from the sunspot center. Within a 6 Mm ring around the
  outer sunspot border, most BP (4/5) move radially outwards; they are
  faster than the minority (1/5) of inward moving BP. The difference of
  both velocities indicates a radial outward drift which decreases from
  about 0.3 km s<SUP>-1</SUP> at the outer penumbral border to zero at
  about 20 Mm distance (28\arcsec) from the sunspot center; a spatial
  range that we interpret as the extension of the sunpot “moat”. This
  finding supports the idea of giant rolls in deep layers measured by
  helio-seismic tomography and predicted by theory. Inside the penumbra,
  we find a 4/5 majority of penumbral bright structures (PBS) to move
  inwards with a mean velocity of 0.8 km s<SUP>-1</SUP>. The 1/5 minority
  of outward moving PBS is almost entirely located in the outer penumbra;
  their mean velocity of 0.8 km s<SUP>-1</SUP> is equally found for
  penumbral dark structures (PDS) in the outer penumbra, in agreement
  with penumbral MHD models.

---------------------------------------------------------
Title: Spectroscopy of Solar Prominences Simultaneously From Space
    and Ground
Authors: Stellmacher, G.; Wiehr, E.; Dammasch, I. E.
2003SoPh..217..133S    Altcode: 2013arXiv1303.1126S
  We present a comprehensive set of spectral data from two quiescent
  solar prominences observed in parallel from space and ground: with
  the VTT, simultaneous two-dimensional imaging of Hβ4862 Å and Caii
  8542 Å yields a constant ratio, indicating small spatial pressure
  variations over the prominence. With the Gregory, simultaneous spectra
  of Caii 8542 Å and Hei 10830 Å were taken, their widths yielding
  8000 K &lt;T<SUB>kin</SUB>&lt;9000 K and 3&lt;v<SUB>nth</SUB>&lt;8
  km s<SUP>−1</SUP>. The integrated line intensities show a distinct
  relation E(Hei) versus E(Caii) for each prominence (`branching'). The
  intensity ratio of the helium triplet components is used for a
  simple estimate of the optical thickness, which is τ&lt;1.0 for the
  fainter prominence but reaches up to τ=2.0 for the brighter one. The
  τ<SUB>0</SUB> values allow us to deduce the source function from
  the central line intensities and thus a mean excitation temperature
  T<SUB>ex</SUB><SUP>mean</SUP>=3750 K, which determines the relative
  populations of the helium <SUP>3</SUP>S and <SUP>3</SUP>P levels. With
  SUMER, we sequentially observed six spectral windows containing
  higher Lyman lines, `cool' emission lines from neutrals and singly
  charged atoms, as well as `hot' emission lines from ions like Oiv,
  Sv, Nv, Ov, and Svi. The spatial variation of the EUV lines along the
  SUMER slit shows a pronounced maximum at the main prominence body and
  `side-regions' where the `hot' lines are significantly enhanced with
  respect to the `cool' lines from neutral and singly-ionized atoms. These
  selected locations were averaged over 7” and the resulting mean EUV
  lines were fitted by Gaussians yielding realistic widths and integrated
  line intensities. The intensities of `hot' lines blue-wards of the
  Lyman series limit appear reduced in the main prominence body but
  enhanced in the `side-regions'. This absorption is also visible in TRACE
  images of Feix/x171 Å as fine dark structure which covers only parts
  of the main (`cool') prominence body. The Lyman lines show a smooth
  decrease of both line widths and integrated emission, with increasing
  upper level k=5 to k=19; the widths are smaller for the prominence
  that yields lower T<SUB>kin</SUB> from the ground-based spectra. The
  level populations along the line of sight follow for 5 lekle a smooth
  Boltzmann distribution with T<SUB>ex</SUB>&gt;6×10<SUP>4</SUP> K, the
  levels k&gt;8 appearing more and more overpopulated. The larger widths
  of the Lyman lines require high non-thermal broadening close to that of
  `hot' EUV lines. In contrast, the Heii emission is more related to the
  `cool' lines.

---------------------------------------------------------
Title: Solar prominence polarimetry
Authors: Wiehr, E.; Bianda, M.
2003A&A...404L..25W    Altcode:
  We measure the resonance polarization in solar prominences in Hα ,
  Hβ and HeD<SUB>3</SUB>. A two-dimensional set-up with narrow-band
  filter, polarization analyzer and CCD camera is used to take prominence
  images in polarized light at high spatial resolution. Placed on a
  coudé telescope's hour axis, the observations near the equinoxia
  are free from purely instrumental polarization. Above the 0.1% noise
  limit, the Balmer lines do not show a polarization in contrast to the
  HeD<SUB>3</SUB> line. Here, we determine the complete polarization
  profile after exchange of filter and CCD with the spectrograph, keeping
  the polarization analyzer fixed. In most prominences the Stokes-U and
  -Q profiles are not similar to Stokes-I: occasionally the blue and
  the red components of the emission are equal or even show a reverse
  ratio. This fits calculations for magnetic field strengths of the
  order of 50 Gauß being markedly stronger than commonly assumed.

---------------------------------------------------------
Title: High spatial resolution solar polarimetry with interference
    filters
Authors: Wiehr, E.; Bianda, M.
2003A&A...398..739W    Altcode:
  A new type of two-dimensional polarimeter is used to measure the
  center-to-limb variation of the scattering induced polarization in a
  narrow continuum window up to the extreme limb. The polarimeter is set
  on the Tenerife Gregory Coudé telescope's hour axis, where the two
  folding flat mirrors cancel their polarizing effects for zero solar
  declination at the equinox. The short CCD exposure of only 5 ms allows
  high spatial resolution images in polarized light. A beam switching
  technique together with an integration parallel to the solar limb
  over 20\arcsec, yields a high polarimetric accuracy with an rms noise
  of 2*E<SUP>-4</SUP>. Our results for a continuum window at 4506-4508
  Å agree with model calculations down to limb distances of 0\farcs32
  (i.e. cos vartheta &lt; 0.025).

---------------------------------------------------------
Title: Continuum limb polarization at high spatial resolution
Authors: Bianda, M.; Wiehr, E.
2003AN....324..323B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: GREGOR - optical design considerations
Authors: Soltau, D.; Berkefeld, Th.; von der Lühe, O.; Hofmann, A.;
   Schmidt, W.; Volkmer, R.; Wiehr, E.
2003AN....324..292S    Altcode:
  After many years of successful work the Gregory Coudé Telescope
  (GCT) is going to be replaced by GREGOR. This new 1.5 m telescope is
  the result of design considerations which to a wide extent are based
  on new technologies. Special aspects of the design are presented,
  including measures to compensate for optical aberrations caused by
  instrumental and atmospheric effects (Adaptive Optics). First light
  is expected for the end of 2004.

---------------------------------------------------------
Title: From the Gregory-Coudé Telescope to GREGOR: a development
    from past to future.  Summary of workshop held in Göttingen, July
    24-26, 2002
Authors: Kneer, F.; Wiehr, E.; Wittmann, A. D.
2003AN....324..283K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Automatic guiding of solar Gregory telescopes
Authors: Küveler, G.; Wiehr, E.; Bianda, M.
2003AN....324..308K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Spectroscopy of solar prominences from space and ground
Authors: Dammasch, I. E.; Stellmacher, G.; Wiehr, E.
2003AN....324..338D    Altcode:
  Two quiescent solar prominences were observed in July 2000 from
  SUMER aboard SOHO and from the two German solar telescopes at
  Tenerife. Two-dimensional images taken at the VTT simultaneously in the
  spectral lines Hβ at 4862 Å and Ca II at 8542 Å show no significant
  spatial variation of their pressure-sensitive emission ratio. Slit
  spectra of the Ca II 8542 Å and He i 10830 Å lines obtained at the
  Gregory-Coudé telescope yield 8000 K &lt; T_kin &lt; 9000 K and 3 km/s
  &lt; V_n-th &lt; 8 km/s. Among the various spectral ranges observed with
  SUMER, we first investigate the Lyman emission lines, which were fitted
  by Gaussians yielding reliable spectral radiances and line widths for
  the series members 5&lt;k&lt;18. A determination of the level population
  gives for the lower series members a Boltzmann temperature of 60 000 K,
  the higher members being over-populated. This temperature indicates an
  origin of the Lyman lines from hot surroundings of the cool prominence
  body seen in the ground-based data; this also holds for the `hotter'
  SUMER lines.

---------------------------------------------------------
Title: Removing instrument and dome from the GCT building
Authors: Duensing, U.; Harke, R.; König, D.; Wiehr, E.
2003AN....324..317D    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: From the first Gregory-Coudé Telescope to Gregor
Authors: Wiehr, E.
2003AN....324..285W    Altcode:
  The historic development of the Göttingen Gregory-Coudé Telescope
  is sketched. The use of a Gregory system for a solar telescope was
  driven by the severe disadvantages of an existing Cassegrain solar
  telescope. The possibility of placing a (water-cooled) field-stop at
  the prime-focus diminishes heat stress as well as straylight on the
  mirrors behind the field-stop. The measured aureole intensity of the
  first solar Gregory telescope, installed 1959 near Locarno, classifies
  that instrument as a `quasi coronograph' and makes it particularly
  suitable for straylight-sensitive observations. The coudé mounting
  with two folding flat mirrors (`German type') assures small and
  daily constant instrumental polarization. This was compensated in a
  first step with a co-rotating tilted glass-plate and a modified Bowen
  compensator fixed to the hour axis. In a later step, a half-wave plate
  between both folding flat mirrors simulates the polarimetric situation
  of zero-declination. The Gregory-Coudé Telescope was then particularly
  suitable for polarimetry; it operated 25 years near Locarno and finally
  15 years on Tenerife.

---------------------------------------------------------
Title: Two-dimensional polarimetry in solar prominences at high
    spatial resolution
Authors: Wiehr, Eberhard
2002ESASP.505...33W    Altcode: 2002solm.conf...33W; 2002IAUCo.188...33W
  Two-dimensional images of solar prominences in polarized light are
  obtained at the evacuated Gregory-Coudé telescope on Tenerife. A linear
  polarization analyzer with CCD camera is placed on the telescope's hour
  axis. Prominence emission lines are selected by narrow filters of a
  few Angstrom widths. This set-up allows short exposure times of a few
  milliseconds yielding spatially very high resolved two-dimensional
  prominence images in the polarized light. The particular Coudé
  mounting assures a daily constant instrumental polarization. For
  zero solar declination near the equinoxia, where the two folding flat
  mirrors are oriented perpendicular to each other, this polarization
  largely vanishes. We applied our method to prominence emissions of
  H-alpha, H-beta and He-D<SUB>3</SUB>. The Balmer lines show no linear
  polarization in excess of the 3×10<SUP>-4</SUP> noise level. For
  He-D<SUB>3</SUB> we find a linear polarization of a few percent;
  its relation to the prominence fine-structure is discussed.

---------------------------------------------------------
Title: Two-dimensional distribution of oscillations in a quiescent
    solar prominence
Authors: Terradas, J.; Molowny-Horas, R.; Wiehr, E.; Balthasar, H.;
   Oliver, R.; Ballester, J. L.
2002A&A...393..637T    Altcode:
  Using time series of two-dimensional Dopplergrams, a temporal and
  spatial analysis of oscillations in a quiescent prominence has been
  performed. The presence of an outstanding oscillatory signal in the
  acquired data has allowed us to study the two-dimensional distribution
  of wave motions and, in particular, to detect the location of wave
  generation and the anisotropic propagation of perturbations from that
  place. Moreover, a strong damping of oscillations has been observed,
  with damping times between two and three times the wave period. The
  direction of propagation, wavelength and phase speed, together with
  the damping time and wave period, have been quantified and their
  spatial arrangement has been analysed. Thanks to the goodness of the
  observational data, the image alignment procedure applied during
  the data reduction stage and the analysis tools employed, it has
  been possible to carry out a novel and far-reaching observational
  study of prominence oscillations. The five movies are available at
  http://www.edpsciences.org

---------------------------------------------------------
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.
2002NCimC..25..689K    Altcode:
  No abstract at ADS

---------------------------------------------------------
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.
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: Spatial offsets between lines and continuum in limb faculae
Authors: Stellmacher, G.; Wiehr, E.
2001SoPh..202..259S    Altcode:
  High-spatial-resolution spectra of limb faculae show spatial
  displacements of line cores relative to the adjacent continuum at cos
  θ&lt;0.35, confirming results from earlier photographic analyses. The
  observed displacements are geometric measures which probe the upper
  atmospheric layers of fluxtubes forming facular grains. We selected
  spectra with highest contrast and smallest width of the facular
  continuum streaks, in order to avoid clustered structures. The spatial
  displacements of Stokes-Q and -V maxima were also measured: we find
  Q-signals spatially located near the continuum, as is expected from
  their origin in line wings; V-signals - which should give evidence
  for the existence of horizontal fields - are not found, except for
  one case of a 'hidden' pore.

---------------------------------------------------------
Title: A New Algorithm for Pattern Recognition and its Application
    to Granulation and Limb Faculae
Authors: Bovelet, B.; Wiehr, E.
2001SoPh..201...13B    Altcode:
  We have developed a new pattern-recognition algorithm based on
  multiple intensity clips which assures an optimal adaptation to the
  solar structure under study. The shapes found at higher clip levels
  are repeatedly extended to lower levels, thus filling more and more
  of the observed intensity contours. Additionally, at each intensity
  threshold new shapes, exceeding the level, are integrated. The number
  and height of the levels can be optimized making this `multiple level
  tracking' algorithm (MLT) superior to commonly used Fourier-based
  recognition techniques (FBR). The capability of MLT is demonstrated
  by application to the intensity structure of solar granulation near
  the disk center, both speckle reconstructed and not. Comparisons with
  Doppler maps prove its reliability. The granular pattern recognized
  by MLT differs essentially from that obtained with FBR. Elongated
  `snake-like' granules do not occur with MLT and, consequently, the
  perimeter-area distribution exhibits only a marginal `second branch'
  of higher fractal dimension, which dramatically diminishes the better
  the MLT pattern matches the granular structure. The final distribution
  obtained with optimized parameters has a single fractal dimension near
  1.1, making the question of a `critical size', a `second branch',
  and the often discussed dimension of 4/3; highly questionable. This
  result is equally obtained from application of MLT to the corresponding
  Doppler velocity map of granular up-flows. In contrast, the pattern
  of down-flows contains some elongated `snake-like' structures with
  higher fractal dimension. We also use the new algorithm to recognize
  speckle-reconstructed limb faculae, which MLT separates from their
  granular surroundings, and compare both, granules and faculae, using
  large statistical samples. The facular grains near cosθ=57° exhibit a
  slightly different ellipticity than the (geometrically foreshortened)
  adjacent granules. However, small facular grains are more round than
  small granules and larger grains are more similar to granules.

---------------------------------------------------------
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.
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: Magnetic field strength and inclination in the penumbral
    fine-structure
Authors: Wiehr, E.
2000SoPh..197..227W    Altcode: 2012arXiv1210.2870W
  The uncertainty about a possible correlation between magnetic field
  strength, inclination, and the continuum intensity of sunspot penumbral
  fine-structure has been removed from detailed analysis of a spatially
  very well-resolved spectrum: the darker, long penumbral lanes host a 10%
  stronger and ≤ 30° flatter magnetic field as compared to the field
  in bright penumbral locations. This finding is not only based on the
  high spatial resolution but also on the use of a spectral line, here Fe
  6842.7 Å, obtaining its essential contribution from those deep layers
  where the penumbral structure is seen, i.e. the continuum intensity
  level. The almost perfect correlation establishes that the penumbral
  structure is formed by the two magnetic components mainly differing by
  the field inclination. The different results from other Zeeman lines,
  as, e.g., Fe 6302.5 Å, indicate a different field structure above
  the white-light penumbral layers.

---------------------------------------------------------
Title: Two-dimensional photometric analysis of emission lines in
    quiescent prominences
Authors: Stellmacher, G.; Wiehr, E.
2000SoPh..196..357S    Altcode:
  Emission lines from quiescent prominences were observed simultaneously
  through narrow-band interference filters, thus integrating the total
  line intensities without the use of a spectrograph. Simultaneous
  exposures (50 ms) on three electronically connected CCD cameras at
  the 70 cm VTT on Tenerife assured almost identical influence of the
  Earth's atmosphere and a spatial resolution of ≤ 1 arc sec. The
  resulting spatially high-resolution two-dimensional images in Hβ,
  Hα, and Ca<SUP>+</SUP>8542, calibrated in units of the disk-center
  intensities, allow a two-dimensional mapping of emission ratios yielding
  relevant physical parameters. The emission relation between Hα and
  Hβ, which depends on the total optical thickness, confirms earlier
  photometric results from spectra, however, with a large sample of data
  points from six prominences. It demonstrates the saturation effects
  towards brighter prominences or prominence locations. The relation
  between Ca<SUP>+</SUP>8542 and Hβ, which depends on the gas pressure,
  is found to vary between different prominences but is nearly constant
  within one prominence. Its mean spatial variation of ≤ 30% within
  one prominence may be interpreted in terms of a magnetic field with
  variations of ≤5%. The brightness distribution in most prominences
  is not smooth but indicates preferred values, which are interpreted
  as superpositions of several fine structures.

---------------------------------------------------------
Title: Applying speckle masking to spectra
Authors: Sütterlin, P.; Wiehr, E.
2000SoPh..194...35S    Altcode:
  We have applied the technique of speckle masking to spectra. The
  observation of elongated solar structures avoids the problem of missing
  information in one-dimensional spectra. Image motion perpendicular
  to the slit was diminished by a one-dimensional image stabilization
  system. The remaining influence of the Earth's atmosphere was removed
  by a modified speckle-masking algorithm, adapted to the single spatial
  dimension occurring in the spectra. The reconstructed spectra achieve
  the diffraction limit of the telescope and the spectrograph.

---------------------------------------------------------
Title: Two-dimensional Mapping of Emission Ratios in Quiescent
    Prominences
Authors: Wiehr, E.; Stellmacher, G.
1999ESASP.448..435W    Altcode: 1999ESPM....9..435W; 1999mfsp.conf..435W
  No abstract at ADS

---------------------------------------------------------
Title: Continuum photometry of solar white-light faculae
Authors: Sütterlin, P.; Wiehr, E.; Stellmacher, G.
1999SoPh..189...57S    Altcode:
  We have determined absolute continuum intensities and brightness
  temperatures of individual facular grains at a spatial resolution
  limited by the φ=50 cm aperture of the SVST on La Palma. A facular
  region at θ≈57° was observed simultaneously in three narrow
  continuum windows at 450.5, 658.7, and 863.5 nm. We corrected for
  image degradation by the Earth's atmosphere using the speckle masking
  method. The brightness temperatures do not exactly follow the Planck
  law. The differences of T<SUB>blue</SUB>−T<SUB>red</SUB>=220
  K and T<SUB>ir</SUB>−T<SUB>red</SUB>=−42 K reflect the
  wavelength dependence of the continuum formation depth. The (red)
  temperatures of 250 facular grains show excesses between 250
  and 450 K above their undisturbed neighborhood. The wavelength
  dependence of the relative intensity ratios C<SUB>λ</SUB>=
  [I<SUP>fac</SUP>/I<SUP>phot</SUP>] <SUB>λ</SUB>show a large scatter
  around mean values of C<SUB>blue</SUB>/C<SUB>red</SUB>=1.075 and
  C<SUB>ir</SUB>/C<SUB>red</SUB>=0.98. We determined the center-to-limb
  variation of the 863.5 nm continuum contrast for 0.17&gt;cosθ&gt;0.39
  by measuring 270 grains in reconstructed facular images. The
  upper envelope of the data points increases linearly to 1.5 at
  cos θ=0.17. Application of the mean color dependence yields green
  contrasts up to C<SUB>550</SUB>=1.7, which is far higher than previously
  observed values. The behaviour for cos θ&gt;0.17 is estimated from
  (unreconstructed) frame-selected best images taken over a time interval
  of 7 hours. Six distinct facular regions clearly discernible during
  the whole time interval indicate a slight contrast decrease towards
  the extreme limb. The observed quantities are useful for an adjustment
  of model calculations and for a discrimination of competing models.

---------------------------------------------------------
Title: Mass Motions and Magnetic Fields in Penumbrae
Authors: Wiehr, E.
1999ASPC..184...86W    Altcode:
  Results from sunspot penumbral spectra of photospheric lines
  are discussed under the particular aspect of the structuring of
  magnetic fields and of the Evershed effect. Since the pioneering
  papers in the mid-sixties, a variety of observations were made at
  increasing spatial resolution. These establish spatially altering
  steeper and flatter penumbral flux-tubes. The Evershed effect seems
  to be located in the flatter field structure which has weaker field
  strengths. No clear relation is found between the spatial structure
  of the continuum intensity and that of the magnetic field and of the
  Evershed effect. This even holds for speckle reconstructued spectra
  which achieve a spatial resolution of 0.2 arcsec. The relation to the
  line-core intensities is closer; possibly since these originate from
  similar layers as those where field and flow are measured.

---------------------------------------------------------
Title: Protuberanzen - glühendes Plasma in der Magnet-Falle.
Authors: Wiehr, E.
1999S&WSp...4...50W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Prominence Doppler oscillations.
Authors: Molowny-Horas, R.; Wiehr, E.; Balthasar, H.; Oliver, R.;
   Ballester, J. L.
1999joso.proc..126M    Altcode:
  Longitudinal velocity maps have been constructed from time series
  of Hβ filtergrams, obtained at three positions along the emission
  line profile. Several examples of velocity perturbations with a
  periodic behaviour have been found at different spatial locations in
  the prominence. Periods have been determined to vary approximately
  between 28 and 95 minutes. The presence of damping (and in one case,
  of excitation) in those oscillatory motions is discussed.

---------------------------------------------------------
Title: Automatic guiding of the primary image of solar Gregory
    telescopes
Authors: Küveler, G.; Wiehr, E.; Thomas, D.; Harzer, M.; Bianda,
   M.; Epple, A.; Sütterlin, P.; Weisshaar, E.
1998SoPh..182..247K    Altcode:
  The primary image reflected from the field stop of solar Gregory
  telescopes is used for automatic guiding. This new system avoids
  temporal varying influences from the bending of the telescope tube by
  the main mirror's gravity and from offsets between the telescope and
  a separate guiding refractor. The required stiffness of the guider
  mechanics and the small areas of the sensors demand small f numbers
  for the guider optics, which cause problems with the image quality and
  with heat. Problems also arise from the pinhole in the telescope's
  field stop which is imaged as a dark dot on the sensor. Pointing
  errors introduced by the telescope affect shifts of the solar image
  on the sensor. These are numerically determined by Fourier methods
  which are found to be less sensitive to noise than profile centering
  methods. Several types of guiders are tested, the final equipment,
  now installed at the Gregory telescopes at Tenerife and at Locarno,
  is described.

---------------------------------------------------------
Title: Temperature mapping of sunspots and pores from speckle
    reconstructed three colour photometry
Authors: Suetterlin, P.; Wiehr, E.
1998A&A...336..367S    Altcode:
  The two-dimensional temperature distribution in a highly structured
  sunspot and in two small umbrae is determined from a three-colour
  photometry in narrow spectral continua. Disturbing influences from
  the earth's atmosphere are removed by speckle masking techniques,
  yielding a spatial resolution limited by the telescope's aperture. The
  corresponding colour temperatures are consistent over a range of
  more than 2000 K, although the numerical correction introduced by
  the reconstruction differs largely for the three colours. Part of the
  scatter in the temperature relation disappears when convoluting the
  final images with artificial PSFs that compensate for the different,
  colour dependent spatial resolution. The remaining spread in the
  scatter plots does not reflect noise, but is related to local
  variations of the temperature difference between the continuum
  emitting layers. This is most obvious for a small umbra which yields
  `branches' in the scatter plots the `bluer' of which corresponding to
  the limb-side umbral border. Here, the `hot rim' of a Wilson depressed
  umbra becomes visible. The temperature map of the large spot shows that
  the bright umbral dots do not reach the temperature of the non-spot
  surroundings. Instead, they exceed the 2000 K cooler umbral temperature
  minimum by 900-1300 K. The filamentary structure of the surrounding
  penumbra has spatial temperature fluctuations of typically 700 K,
  a value which fits earlier observed contrasts. However, the mean
  temperatures of 5650 K in the dark and 6250 K in the bright penumbral
  fine structures exceed former findings. Exceptionally bright penumbral
  grains are 250 K hotter than the mean solar surface and thus exceed
  even brightest granules.

---------------------------------------------------------
Title: The hot prominence periphery in EUV lines
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1998A&A...334..280D    Altcode:
  Two sets of He I and metallic lines were observed with the EUV
  spectrograph SUMER in a quiescent prominence. H, He, and Ca II
  lines were observed simultaneously with both German telescopes on
  Tenerife. The visible lines from elements with different atomic
  weights yield thermal and non-thermal broadening parameters of 7500
  &lt;= T<SUB>kin</SUB> &lt;= 8000 K and 2.5 &lt;xi &lt;5.0 km/s for the
  cool prominence body. The EUV lines, however, show line widths which
  correspond to much higher temperatures and non-thermal velocities. If
  the calculated formation temperature for every individual ion is
  assumed, the observed line widths require non-thermal velocities of 14 -
  25 km/s. The narrowest reduced widths of the EUV He I 584 and He I 537
  lines are 3.1 and 2.9 times broader than those of the visible He D_3
  and He 3888 lines. If this is due to optical depth effects in the EUV
  lines, one obtains tau_0 (584) ~ 8*10(3) and tau_0 (537) ~ 2*10(3)
  , respectively. The emission ratios of the Ca II-to-Balmer lines
  vary little inside the prominence, indicating a largely constant gas
  pressure. The ratios of the visual He-to-Balmer lines as well as those
  of the EUV He-to-metallic lines show a significant branching between
  peripheral and central prominence regions. The total emissions in the
  main prominence body amount to 13, 0.3, and 4 [Watt/ (m(2*) ster)]
  for the 584, 537, and D_3 lines, respectively. The observed emission
  ratio E(He 584)/E(He 537)= 45 agrees with model calculations whereas
  their total emissions are about 37 times higher than calculated. The
  observed ratio E(He D_3)/ E(He 584)~0.3 is about 15 times smaller
  than model predictions. The observations indicate that the emissions
  of different ions originate from individual (isothermal) threads with
  different temperatures between 10(4) and 10(5) K.

---------------------------------------------------------
Title: 3-Color Photometry of a Sunspot Using Speckle Masking
    Techniques
Authors: Sütterlin, P.; Wiehr, E.
1998ASPC..155...44S    Altcode: 1998sasp.conf...44S
  No abstract at ADS

---------------------------------------------------------
Title: Prominence Emissions with SUMER and Optical Telescopes
Authors: Wiehr, E.; Stellmacher, G.; de Boer, C. R.; Sütterlin, P.
1998ASPC..155..331W    Altcode: 1998sasp.conf..331W
  No abstract at ADS

---------------------------------------------------------
Title: Prominence Emission Lines Observed with SUMER and Two
    Ground-Based Telescopes
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1998ASPC..150..196D    Altcode: 1998npsp.conf..196D; 1998IAUCo.167..196D
  No abstract at ADS

---------------------------------------------------------
Title: Three colour photometry of solar limb faculae.
Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E.
1997A&A...324.1179D    Altcode:
  The contrasts of limb faculae at various heliocentric angles are
  observed in three continuum windows largely free of absorption
  lines. Observations with interference filters show a contrast decrease
  with wavelength which is not found when using an `UBF' to select the
  shortest continuum window. Limb faculae in speckle-reconstructed images
  yield contrasts being typically 1.2 times higher than those deduced from
  the `best images' of the corresponding bursts. The fit of the wavelength
  dependence (`colour index') to a black-body law is significantly better
  for the contrasts deduced from the reconstructed images than for the
  contrasts from the best images. The uncorrected contrasts yield a mean
  facular temperature excess of 200-300K; those from the reconstructed
  images yield about 470 K. The center-to-limb variation is found to be
  much smaller than the fluctuations between individual faculae.

---------------------------------------------------------
Title: Problems in measuring prominence oscillations.
Authors: Suetterlin, P.; Wiehr, E.; Bianda, M.; Kueveler, G.
1997A&A...321..921S    Altcode:
  Time variations of Doppler shifts of the Ca^+^ 8542Å emission in
  quiescent solar prominences have been measured. A new type of 'limb
  guider' assures a highly constant distance of the spectrograph slit from
  the solar limb and furthermore removes low frequency image motion in the
  direction perpendicular to the slit. Remaining image motion along the
  slit is usually removed by a correlation of subsequent spectra. This
  procedure, however, cannot be applied globally to the whole spatial
  height in the spectra if individual structures exhibit lateral motions
  along the slit or even decay or arise during the observation. We
  therefore correlate defined individual emission maxima from successive
  spectra. The finally obtained power spectra show oscillations with a
  variety of periods at restricted locations. The data favour the known
  general presence of periods near 20 and 60-min, however they give only
  slight indication for `typical' periods near 3 and 5 min.

---------------------------------------------------------
Title: The Depth Dependence of Penumbral Absolute Velocities
Authors: Balthasar, H.; Schmidt, W.; Wiehr, E.
1997SoPh..171..331B    Altcode:
  Penumbral line-core shifts at different heights are determined from
  the lines Fei 5434.5 Å, Fei 5435.2 Å, and Nii 5435.8 Å using two
  adjacent water vapor lines for an absolute wavelength scale. The large
  granular blue shift of 0.6 km s<SUP>-1</SUP> for the faint Fe 5435
  line from deep layers yields for the centre-side penumbra absolute
  velocities up to 3 km s<SUP>-1</SUP>. This value is much larger than
  velocities deduced from the bisectors of the line wings of Ni 5436 and
  Fe 5434, thus supporting the concern against an interpretation of the
  line asymmetries in term of a velocity gradient with depth.

---------------------------------------------------------
Title: The helium singlet-to-triplet line ratio in solar prominences.
Authors: Stellmacher, G.; Wiehr, E.
1997A&A...319..669S    Altcode:
  The emissions of the He singlet line at 6678Å and the He triplet line
  at 4471Å are simultaneously observed in three solar prominences. For
  two of them, the line pairs He-D_3_/H<SUB>beta</SUB>_ and
  Ca^+^8662/H<SUB>beta</SUB>_ were also observed. Comparisons with model
  calculations show that the emission line ratios require low densities
  (n_H_=~3.10^10^cm^-3^), low gas pressures (P_g_=~0.02dyn/cm^2^),
  and large physical slab widths. The relative He-to-H number density
  cannot be much lower than y=0.1.

---------------------------------------------------------
Title: Three colour photometry of a sunspot using speckle masking
    techniques.
Authors: Sütterlin, P.; Wiehr, E.
1997AGAb...13...10S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Sharp Boundary of Magnetic Field and Flow in Sunspot
    Penumbrae
Authors: Wiehr, E.
1997ASPC..118..175W    Altcode: 1997fasp.conf..175W
  The line asymmetry, characteristic signature of the Evershed effect,
  ends abruptly at the outer sunspot border defined by the ends of the
  dark penumbral structures. This is most impressively demonstrated
  by the absence of line asymmetries at the center-side of sunspots
  close enough to the limb that the Wilson effect makes that penumbra
  invisible. It supports the idea that the line asymmetries are produced
  by a superposition of Doppler-shifted profiles from the dark, and less
  shifted profiles from the bright penumbral structures.

---------------------------------------------------------
Title: Emission Lines in a Quiescent Prominence Observed with the
    SUMER, VTT, a nd Gregory Telescopes
Authors: Wiehr, E.; de Boer, C. R.; Stellmacher, G.; Sutterlin, P.
1997ASPC..118..294W    Altcode: 1997fasp.conf..294W
  A number of emission lines have been observed in a quiescent prominence
  with the two German telescopes on Tenerife and with SUMER. The Gregory
  telescope monitored simultaneously the lines H_8 3889, He 3888, Ca(+\:)
  8498, the VTT simultaneously the lines H_β, He-D_3, Ca(+\:) 8542, and
  H_α slit jaw pictures on 1024 x 1024 CCDs. At the same time, SUMER
  monitored successively three combinations of EUV lines containing He
  584, He 537 in the second, and Ar, N(+) , C, C(++) , O, O(+) , O(++)
  , S(++) , S(+++) lines in the first order. Two dimensional images in
  the various EUV lines establish the anti-relation between temperature
  and Balmer brightness.

---------------------------------------------------------
Title: The structure of sunspot penumbrae.
Authors: Wiehr, E.
1996NAWG.1996..193W    Altcode:
  At sufficiently large heliocentric angles θ ≥ 65° where the
  line-of-sight is almost parallel to the penumbral filaments, the line
  asymmetry of the Evershed effect shows up as a distinct "kink" in the
  line wings. It can be explained by a superposition of a main component
  from the bright penumbral structures containing a very small gasflow
  and a line satellite from the dark structures containing a gasflow
  of 5.2 km s<SUP>-1</SUP> at 250 km and 7.7 km s<SUP>-1</SUP> at 550
  km height. This flow is just strong enough to yield a Doppler shift
  of the line satellite slightly larger than the line halfwidths. Any
  inclination of the line-of-sight with respect to the structures reduces
  the distance of the satellite. The kink is therefore absent in limb-side
  penumbrae and in spots at smaller viewing angles. In such cases, the
  superposition produces a "smooth" asymmetry without a kink, but with
  an additional line core shift of maximally 0.8 km s<SUP>-1</SUP>.

---------------------------------------------------------
Title: A search for formation-height oscillations in umbrae.
Authors: Berger, B.; Balthasar, H.; Schleicher, H.; Wiehr, E.;
   Woehl, H.
1996A&A...310..328B    Altcode:
  The formation heights of spectral lines and continua in sunspots can be
  determined by measuring the apparent distance of the spot relative to
  the nearby solar limb. In order to confirm the existence of oscillatory
  variations of such limb distances and to exclude possible influences
  of differential image motion between the spot and the nearby limb, we
  have obtained time series observations of the lines Ca^+^ 8542, Mg b,
  and the non-magnetic line Fe 5576 simultaneously on two telescopes. No
  indication is found for periodic fluctuations of the spot's apparent
  limb distance. Only one of the seven time series shows a significant
  40 min period of the line core but not of the continuum in the data
  from both telescopes. This variation of the line formation height,
  however, may be attributed to parallel guiding corrections of a
  spatially inhomogenous umbral chromosphere. The other time series
  show different periods for the two telescopes, which must be caused
  by unrelated guiding corrections.

---------------------------------------------------------
Title: The spatial structure of the Evershed effect.
Authors: Wiehr, E.
1996A&A...309L...4W    Altcode:
  The line asymmetry from the Evershed effect disappears beyond the
  boundary of the white-light penumbra over a horizontal distance of
  less than 500km. Immediately beyond the ends of the dark penumbral
  continuum structures, the lines NiI5435.9 (g=0.5) and FeI5434.5 (g=O;
  formed about 300km higher) simultaneously lose their asymmetry. The
  spatial distance of maximally 500km is too short for a "disappearence
  with height" as suggested by models of a penumbral "canopy". Instead,
  the data favour a rather flat orientation of the dark structures with
  an abrupt disappearance. It is suggested that this location marks
  the sharp threshold of the equipartition between kinetic and magnetic
  energy density at the outer penumbral border.

---------------------------------------------------------
Title: Branching of the helium-to-Balmer emission ratio in solar
    prominence structures.
Authors: Stellmacher, G.; Wiehr, E.
1995A&A...299..921S    Altcode:
  The H<SUB>alpha</SUB>_, H<SUB>beta</SUB>_, and He D_3_ emission
  lines are simultaneously observed with high spatial resolution at
  the VTT on Tenerife. It is found that the emission ratios He D_3_/
  H<SUB>beta</SUB>_ and He D_3_/H<SUB>alpha</SUB>_ show typical mean
  values for each individual prominence. This branching is related
  to the mean kinetic temperature and to the structuring of each
  prominence. Whereas the Balmer excitation is almost uniformly
  distributed throughout prominences, the He excitation is enhanced
  in structured prominences of low Balmer brightness or outer parts
  of unstructured bright prominences, where exciting and ionizing EUV
  radiation can freely penetrate. In these regions the He ionization
  may exceed that of hydrogen. The atmospheric prominence parameters
  are not yet sufficiently known to allow a reliable determination of
  the solar Helium abundance.

---------------------------------------------------------
Title: The origin of the Evershed asymmetry.
Authors: Wiehr, E.
1995A&A...298L..17W    Altcode:
  The line asymmetry of the Evershed effect shows up as a distinct "line
  kink" if observed along the penumbral filaments, i.e. in center-side
  penumbrae of spots at θ&gt;=65deg. The kink can be explained
  by a superposition of a main component from the bright penumbral
  structures with a line satellite from the dark structures shifted
  by &gt;=5km/s. The gas flow shows a gradient of 0.8km/s per 100km
  height. The flow is just strong enough to yield a maximum Doppler shift
  of the line satellite slightly larger than the line halfwidths. Any
  inclination of the line-of-sight with respect to the structures reduces
  the distance of the satellite. The kink is therefore absent in limb-side
  penumbrae and in spots at smaller viewing angles. In such cases, the
  superposition produces a "smooth" asymmetry without a kink and a line
  core shift of up to 0.8km/s. Larger core shifts occasionally observed
  indicate additional motions in the bright structures of the order of
  the proper motions of bright penumbral grains. This picture removes
  the contradictions in explaning the asymmetry and the core-shift of
  different lines in terms of velocity gradients.

---------------------------------------------------------
Title: Erforschung von Sonnenprotuberanzen.
Authors: Wiehr, E.
1995S&W....34..442W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Sunspot limb distance variations measured simultaneously with
    two telescopes.
Authors: Berger, B.; Balthasar, H.; Schleicher, H.; Wöhl, H.;
   Wiehr, E.
1995AGAb...11..142B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Hα and Hβ emissions in solar prominence structures.
Authors: Stellmacher, G.; Wiehr, E.
1994A&A...290..655S    Altcode:
  High precision photometry of the H<SUB>alpha</SUB>_ and
  H<SUB>beta</SUB>_ emissions is performed from spectra of four
  spatially high resolved quiescent prominences. The data are
  compared with recent observations and calculations. It is
  found that for faint emissions the observed Balmer decrement
  D=E_tot_(H<SUB>alpha</SUB>_)/E_tot_(H<SUB>beta</SUB>_) significantly
  exceeds the limiting value D=10.0 calculated for slab models. In
  contrast to former observations, the spatially and spectrally high
  resolved emission profiles do not require a hot and a cool component
  for an optimal fit. The deduced source functions do not yield a common
  value for different prominences, but show an individual mean for each
  prominence with a tendency for an increase with the optical thickness
  of H<SUB>alpha</SUB>_. Optically thick H<SUB>alpha</SUB>_ emissions with
  central absorptions are spatially related with narrow H<SUB>beta</SUB>_
  emissions and hence with small kinetic temperatures. The narrow
  H<SUB>beta</SUB>_ emissions exist over a large range of optical
  thickness and show equal macroscopic shifts for individual emission
  features favouring a picture of closely tied bundles of threads.

---------------------------------------------------------
Title: The Evershed effect in penumbral fine structures. I. Height
    dependence of velocity fluctuations.
Authors: Degenhardt, D.; Wiehr, E.
1994A&A...287..620D    Altcode:
  A number of spectral lines with negligible Zeeman splitting have been
  used for a spectroscopic observation of sunspot penumbrae at different
  slit positions and heliocentric angles: Fe I 5576 simultaneously with
  Si I 6145, and, separately, Fe I 5434 and Ni I 5435 simultaneously with
  Ni I 4912. The formation levels of cores and wings at 20% depression
  were determined from contribution functions to the line depression. The
  spatial fluctuations of the continua, the residual line intensities,
  and the Doppler shifts of cores and wings are separated from a mean
  penumbral variation. A power spectrum analysis shows that the typical
  spatial scale of both the velocity and the intensity fluctuations
  increases with height. The rms velocity fluctuations decrease with
  height, resembling the known granular behaviour. The coincidence of a
  coarser spatial intensity and velocity structure and smaller velocities
  at higher levels favour an explanation by a height dependent filling.

---------------------------------------------------------
Title: The Evershed effect in penumbral fine structures II. Spatial
    correlation analysis.
Authors: Wiehr, E.; Degenhardt, D.
1994A&A...287..625W    Altcode:
  Spatially high resolved spectra of sunspot penumbrae were
  taken simultaneously in a number of lines with negligible Zeeman
  splitting. The formation layers of the different lines span the entire
  height of the penumbral photosphere. The intensity and velocity
  fluctuations from these different levels were subject to a spatial
  coherence and phase analysis which yields the following results: a)
  Spectra with a spatial resolution of at least 0.5 arcsec are necessary
  to detect a perfect correlation between dark penumbral structures
  and wing shifts of lines emerging from deep layers near the continuum
  level. b) This correlation rapidly decreases towards higher levels in
  the penumbra; it almost disappears near the temperature minimum. c)
  The correlation increases when the velocity fluctuations are compared
  with intensity fluctuations of the corresponding residual intensities
  of the line cores rather than with the continuum intensity emerging
  from much deeper layers. d) The line asymmetry ends abruptly with the
  penumbral continuum depression thus suggesting an interpretation of
  a causal relation with the penumbral fine structure. e) If Doppler
  shifts occasionally occur outside the white light penumbral border,
  the corresponding line profiles are symmetric and do not show a
  significant dependence on the formation height.

---------------------------------------------------------
Title: The height variation of sunspot umbral dots.
Authors: Wiehr, E.
1994A&A...287L...1W    Altcode:
  The visibility of sunspot umbral dots is measured in different spectral
  lines that are insensitive to Zeeman splitting. At the formation
  height of the Fe 5576 line core, the dot to inter-dot brightness ratio
  amounts to about 30% of that at the conlinuum level. It further drops
  to less than 15% at the formalion height of the Fe 5576 line core,
  that is expected to correspond to the temperature minimum. A contrast
  of 50% occurs at about 130 km height where the inner wings of Fe 5576
  ({DELTA}λ=45mA) and the outer wings of Fe 5434 ({DELTA}λ=75mA) are
  formed. Simultaneously observed Ni and Si lines from very deep layers
  show the same brightness excess as the adjacent continuum. Neither
  systematic Doppler shifts nor line asymmeties are found in umbral dots
  with respect to their inter-dot neighbourhood.

---------------------------------------------------------
Title: Dependence of the He/H_8_ emission ratio on brightness,
    temperature, and structuring of prominences
Authors: Stellmacher, G.; Wiehr, E.
1994A&A...286..302S    Altcode: 2012arXiv1211.3636S
  The line pair He 3888 and H_8_ 3889 has been observed simultaneously
  with the Ca^+^8498 line in a number of quiescent prominences. The
  He/H_8_ emission ratio R is found to cover defined parts of a general
  anti-correlation with the total H_8_ emission, depending on the
  kinetic temperature, T_kin_, of the individual prominence: High H_8_
  brightness is related to small R and Tkin values and preferably occurs
  in prominences with less significant fine-structure.

---------------------------------------------------------
Title: Temporal and spatial variation of physical parameters in a
    quiescent prominence.
Authors: Balthasar, H.; Wiehr, E.
1994A&A...286..639B    Altcode:
  The emission lines He 3889 A, H_8_ and Ca^+^IR_3_ are observed
  simultaneously in a prominence over a total of 4 hours. The time
  variations of the He 3889 / H_8_ emission ratio R, the thermal and the
  non-thermal line broadenings T_kin_ and ξ, respectively, are compared
  with those of the Doppler shift, v_D_, for 10 spatial locations along
  the slit. The time-averaged spatial variations along the slit show
  an increase of R, T_kin_, and ξ with height related to a decrease of
  the H_8_ emission, E_tot_(H_8_), in agreement with other authors. The
  short-time fluctuations show that quasi-oscillations, known from
  Doppler shifts, also exist for other physical parameters. The long-term
  variations over the total of 4 hours indicate a smooth increase of R,
  T_kin_, and ξ at the upper parts of the prominence, resembling the
  known spatial behaviour of these parameters at prominence edges. Also
  the well known anti-correlation of the emission ratio R and the
  E_tot_(H_8_) occurs in the long-term behaviour. We suggest that the
  decrease of E_tot_(H_8_) parallel with the increase of R might be
  related to a dissolution of the prominence yielding a smaller density
  of fine-structures.

---------------------------------------------------------
Title: Das Sonnenobservatorium im Tessin.
Authors: Wiehr, E.; Bianda, M.
1994S&W....33..108W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Fe I 10265 Å line as an excellent tool for magnetic
    field measurements
Authors: Schmidt, W.; Balthasar, H.; Wiehr, E.
1994ASIC..433...49S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Time saeries of the penumbral Evershed effect.
Authors: Schleicher, H.; Wiehr, E.; Balthasar, H.; Wöhl, H.
1994AGAb...10..113S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Magnetic field strengths in umbral dots
Authors: Wiehr, E.; Degenhardt, D.
1993A&A...278..584W    Altcode:
  Stokes-V and I spectra of sunspot structures have been observed
  simultaneously in the lines Fe 6843 and Ca 6103 originating from
  layers which differ by more than 350 km. The Fe line is totally split
  thus allowing to deduce the field strength from the Stokes-I and V
  profiles. Both splitting values yield a field strength reduction up to
  20% in brighter (peripheral) dots at the umbral border. This reduction
  is not seen in the higher layer where the Ca line originates. The
  faint (central) dots do not exhibit a field strength difference with
  respect to their darker surroundings. Using the ratio of pi to sigma
  depressions of the totally split Fe 6843 line as a measure for the field
  inclination, the field lines are found to be essentially flatter in a
  light bridge than in its neighborhood. Flatter fields are also found
  in some of the peripheral dots. The Doppler shifts of the Fe and of
  the Ca line deviate significantly from each other but do not show a
  relation to the umbral structures.

---------------------------------------------------------
Title: Doppler oscillations in solar prominences simultaneously
    observed with two telescopes. Discovery of a 30 S oscillation
Authors: Balthasar, H.; Wiehr, E.; Schleicher, H.; Wohl, H.
1993A&A...277..635B    Altcode:
  Time series of Doppler shifts are observed simultaneously with two
  telescopes in order to separate actual solar velocities from influences
  of image motion or unperfect guiding. Several maxima of the power
  contours occur only in the data set from one of the two telescopes
  and may thus originate from non-solar sources. Considering only those
  power maxima which are observed with both telescopes we establish the
  solar origin of periods near 20 and 12 min, which may be identified
  with `hybrid fast modes' from model calculations. For one prominence a
  significant period of 30 5 is detected which theory predicts as a wave
  guided by the prominence fine-structures. Our prominence oscillations
  are restricted to spatially small areas of a few arc see diameter.

---------------------------------------------------------
Title: Gasströmung im Magnetfeld von Sonnenflecken-Penumbren.
Authors: Wiehr, E.
1993S&W....32..174W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Influence of non-thermal broadening on the He 3889/H8 emission
    ratio in prominence fine-structures
Authors: Stellmacher, G.; Wiehr, E.; Grupe, D.
1992A&A...265..781S    Altcode:
  The neighboring emission lines H8 and He near 3889 A were observed in a
  quiescent prominence at high spatial resolution. The systematic increase
  of the He/H8 emission ratio R towards the edges of the prominence is
  found to be largely cospatial with a corresponding behavior of the
  nonthermal line-broadening parameter Xi while the thermal broadening
  does not increase. The good relation between R and Xi also exists in
  the fine-structures. This is explained by broadening of the absorption
  coefficient increasing the efficiency of the exciting UV radiation
  preferably for the (heavier) helium. Interpretation of the nonthermal
  broadening parameter in terms of a velocity dispersion may favor the
  influence of waves.

---------------------------------------------------------
Title: Spatial structure of the Evershed effect
Authors: Wiehr, E.; Degenhardt, D.
1992A&A...259..313W    Altcode:
  Spectra of a sunspot penumbra at 27 deg are taken in four adjacent
  slit positions at exceptionally good seeing conditions, yielding
  smallest continuum structures of 0.35 arcsec width. The Doppler shifts
  of line-core and line-wings of the nonmagnetic line Fe I 7090.4 are
  cospatial, but their amplitudes are unrelated. The amount of line
  asymmetry is thus not related to the corresponding line-core shift. A
  good correlation with the continuum occurs only in spectra achieving
  highest spatial resolution. A slightly less resolved spectrum does
  not show a similar correlation, thus explaining the missing relation
  in former observations. The amplitudes of shift and asymmetry are not
  related to those of the continuum intensity. The lack of any amplitude
  relation in spite of an almost perfect spatial correlation among
  shift, asymmetry, and continuum might be explained by the different
  angles-of-view through fine structures aligned along flux tubes of
  individual inclination angles recently observed. In addition, actual
  penumbral structures being essentially smaller than 250 km as deduced
  from white light pictures might yield different influences of spatial
  smearing on continuum, line shift, and line asymmetry.

---------------------------------------------------------
Title: Time series of Doppler velocities in prominences.
Authors: Balthasar, H.; Schleicher, H.; Wöhl, H.; Wiehr, E.
1992AGAb....7..151B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Fluctuation of wing strengths as diagnostic tool for the
    structure of granulation.
Authors: Nolte, U.; Kneer, F.; Wiehr, E.
1992AGAb....7..150N    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Spatial variation of the magnetic field inclination in a
    sunspot penumbra
Authors: Degenhardt, D.; Wiehr, E.
1991A&A...252..821D    Altcode:
  Stokes-V-spectra from a sunspot penumbra show significant spatial
  fluctuations. Due to its deep formation layer, the Fe 6842.7 used is
  totally split (B = 2200 Gs) showing field fluctuations of the order
  of 10 percent. The spatial variations of the Stokes-V spectra are
  strongly affected by telescopic phase retardation thus allowing only a
  rough estimate of the inclination angle. Its fluctuation to the solar
  surface is spatially related to the field-strength fluctuation in the
  sense that steeper fields are stronger. Doppler shifts of the Stokes-V
  give slight indication for upward motions at locations of steeper field
  inclination. A relation with the continuum-intensity fluctuation is
  only found in the center-side penumbra, possibly due to the steeper
  angle-of-view. The absence of a similar correlation in the limb-side
  spectra agrees with earlier findings that field strength and Evershed
  effect are not related to penumbral fine-structures.

---------------------------------------------------------
Title: Modelling the moustache phenomenon in network regions
Authors: Stellmacher, G.; Wiehr, E.
1991A&A...251..675S    Altcode:
  The intensity enhancement in the inner line wings (moustache) of
  Mgb1 5183 and Fe 5434.5 A observed in Ca(+) K bright points outside
  active regions is found to result from a superposition of a hot
  component (representing the magnetic structure) surrounded by a cool
  (intergranular) region. The I + V and I - V profiles of the magnetically
  sensitive line Fe 6302.5, observed strictly simultaneously with Mgb1,
  are equally well modeled by the same procedure (which in an earlier
  paper had successfully been used to explain the gap effect of Zeeman
  insensitive lines in plages). The Mgb1 moustaches are cospatial with
  the simultaneously observed Fe 6302.5 gaps. Their equal spatial extent
  indicates equal width of the temperature and the magnetic structures
  of the Ca(+) K region.

---------------------------------------------------------
Title: Geometric line elevation in solar limb faculae
Authors: Stellmacher, G.; Wiehr, E.
1991A&A...248..227S    Altcode:
  Spectra of markedly visible white light faculae near the solar limb are
  used to determine the geometric displacement, Delta-h, of line cores
  with respect to their adjacent continuum. The observed Delta-h are
  plotted as a function of the excitation potential and, respectively,
  equivalent width of the different lines. Comparison with calculated
  Delta-h from a photospheric LTE model shows that the observed facula
  values significantly exceed the photospheric ones.

---------------------------------------------------------
Title: Stokes-V in an active prominence
Authors: Wiehr, E.; Stellmacher, G.
1991A&A...247..379W    Altcode:
  Stokes-V spectra of the Ca(+)8542 emission were taken with a CCD in
  an active prominence showing extremely high line-of-sight velocities
  up to 25 km/s. The spatial resolution allows detecting prominence
  fine-structures as small as 1.1 arcsec. Exact field strengths were
  determined from the measured steepness of the individual emission line
  flanks. Values between 75 and 180 Gs are obtained. No indication is
  found for a dependence of the field strength on the spatial resolution
  or on the line-of-sight velocity, nor on the emission brightness.

---------------------------------------------------------
Title: Samples of recent high resolution solar observations at
    Tenerife
Authors: Wiehr, E.; Mattig, W.
1991AdSpR..11e.199W    Altcode: 1991AdSpR..11..199W
  The new German telescopes in Izan~a (Tenerife) are now fully
  operational. The first spectroscopic observations demonstrate the
  outstanding quality of the site. Examples of the first scientific
  results are given. They are focused on the fine structure of the
  granulation, small fluxtubes and faculae, the Evershed-effect in
  sunspots and magnetic field strengths in prominences.

---------------------------------------------------------
Title: Oscillations of Evershed velocities and asymmetries
Authors: Balthasar, H.; Wiehr, E.
1990A&A...237..243B    Altcode:
  Four sunspots at different heliocentric angles have been observed to
  study the oscillatory behavior of line asymmetries and velocities due
  to the Evershed effect. For two spots the power maxima of the line core
  velocities and of the line asymmetries are spatially anticorrelated. The
  central part of the penumbra as intersected by the spectrograph slit
  is the location of a velocity power maximum for the one spot, however,
  of an asymmetry power maximum for the other spot. In contrast, for two
  other spots several local power maxima are spatially coincident for
  the line asymmetry and the line core velocity. These variable spatial
  relations of line core velocities and line asymmetries support the
  idea that the Evershed effect may be a result of the superposition of
  penumbral fine structures affected by the underlying oscillating layers.

---------------------------------------------------------
Title: Intensity correlations in granular spectra
Authors: Balthasar, H.; Grosser, H.; Schroeter, C.; Wiehr, E.
1990A&A...235..437B    Altcode:
  Spectra of high spatial resolution were taken at the Gregory-Coude
  Telescope on Tenerife to investigate the relation between the
  line core intensities and the adjacent continuum for selected iron
  lines. Anti-correlations of these two quantities are found for the four
  lines with low excitation potential Fe5079, Fe5434, Fe5501, and Fe5506
  which are known to show a limb effect although they have no blue shift
  at the disk center. An anti-correlation is also found for the line
  with high excitation potential, Fe5074, which shows a very small limb
  effect. This result is compatible with a granular intensity pattern
  which reverses in high layers, as suggested by numerical simulations
  of the granulation.

---------------------------------------------------------
Title: Magnetic field, relative Doppler shift and temperature for
    an inhomogeneous model of sunspot umbrae
Authors: Pahlke, K. -D.; Wiehr, E.
1990A&A...228..246P    Altcode:
  From spatially unresolved umbral Stokes-V spectra, magnetic field
  strength, relative Doppler shift and temperature of a hot and a cool
  umbral component are investigated. The observed Stokes-V profiles are
  compared to numerically superposed Stokes-V profiles calculated with
  various intrinsic model atmospheres and magnetic field parameters and
  filling factors. An optimal fit is obtained if the temperature of the
  hot component lies between that of the undisturbed photosphere and 500
  K less, whereas the cool component is found to be 350 K hotter than
  typical models for darkest umbrae suggest. The hot component covers
  5 percent of the umbral area observed; this value seems to vary from
  spot to spot. The magnetic field strength in the hot component is
  found to be about 20 percent lower than that in the cool component;
  the magnetic field in both components decreases with height by 2 Gs/km.

---------------------------------------------------------
Title: Doppler Velocity Oscillations in Quiescent Prominences
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1990LNP...363..255W    Altcode: 1990IAUCo.117..255W; 1990doqp.coll..255W
  No abstract at ADS

---------------------------------------------------------
Title: Observations of Magnetic Features with the German Solar
    Telescopes at the Observatorio-Del / Tenerife
Authors: Kneer, F.; Soltau, D.; Wiehr, E.
1990IAUS..142..113K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Velocity and magnetic field fluctuations in penumbral
    fine-structures
Authors: Wiehr, E.; Stellmacher, G.
1989A&A...225..528W    Altcode:
  Spatially very highly resolved spectra of sunspot penumbrae show that
  the Evershed effect is not spatially related to the continuum intensity
  fluctuations. The line asymmetry and the core shift (both a signature
  of the Evershed effect) show fluctuations at a larger horizontal scale
  than the continuum and a trend for an anticorrelation, in the sense
  that locations with smaller asymmetry trend to show larger shifts. The
  Zeeman broadening also shows variations at a larger spatial scale
  than the continuum. There is no indication for field enhancements
  in dark continuum streaks, some spots even show a certain trend for
  enhanced field strengths in bright streaks. The absence of a general
  relation to continuum streaks might be explained by the finding that
  the continuum structures in the spectrum are almost invisible at
  the formation height of the Fe 5576-A line, where a coarser spatial
  structure of a few arcsec width occurs.

---------------------------------------------------------
Title: Compensation of image motion and discrimination of blurring
    for spectroscopy
Authors: Wiehr, E.; Pahlke, K. -D.; Koch, A.
1989hsrs.conf..100W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Combination of a 256 x 256 pixel matrix detector and an
    image intensifier
Authors: Balthasar, H.; Wiehr, E.
1989hsrs.conf..345B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The decrease of penumbral velocity and magnetic field at the
    outer sunspot boundary
Authors: Wiehr, E.; Balthasar, H.
1989A&A...208..303W    Altcode:
  Numerical simulation of atmospheric and instrumental smearing
  indicates that velocity and magnetic field disappear at the outer
  spot border within a length of maximally 1650 km and 2200 km,
  respectively. Accepting the (known) inclination of 84 deg, the
  corresponding height ranges of 165 and 220 km, respectively, are not
  compatible with the picture of a disappearance of both fields due to
  a kind of 'optical dilution' with height. Indication is given for a
  disappearance of the fields beyond an iso-tau discontinuity.

---------------------------------------------------------
Title: The Gregory-Coudé- Telescope at the Observatorio Del Teide
    Tenerife
Authors: Kneer, F.; Wiehr, E.
1989ASIC..263...13K    Altcode: 1989ssg..conf...13K
  No abstract at ADS

---------------------------------------------------------
Title: Doppler Velocity Oscillations in Quiescent Prominences
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1989HvaOB..13..131W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Plasma oscillations inside small fluxtubes.
Authors: Wiehr, E.; Lustig, G.
1989sasf.confP.349W    Altcode: 1988sasf.conf..349W; 1989IAUCo.104P.349W
  Periodic Doppler motions inside small fluxtubes are determined from
  the zero-crossing point of the circular Zeeman polarization profile
  (Stokes-V = 0). The gas fully participates on the known solar 5 min
  oscillations without affecting amplitude or frequency. Averaging
  the oscillations, the gas is at rest in an absolute solar
  scale. Discrepancies with formerly observed redshifts are explained
  by the systematic westward displacement of the magnetic structure
  relative to the Ca<SUP>+</SUP>K bright point used for guiding.

---------------------------------------------------------
Title: Oscillations in presence of local magnetic fields.
Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G.
1988ESASP.286..269W    Altcode: 1988ssls.rept..269W
  Oscillatory Doppler shifts in sunspots and in small fluxtubes are
  observed using either the intensity profile of lines with negligible
  magnetic splitting or the circular Zeeman profile (Stokes-V inversion
  point) of lines with strong Zeeman splitting. Sunspot umbrae
  show local 5 min oscillations of reduced amplitude as compared to
  the neighbouring photosphere. Occasionally the authors find 5 min
  oscillations of opposite phase at both outer penumbral borders. This
  could be interpreted as tilting and bobbing of the spot as a whole
  on the oscillating solar surface. In contrast to these larger scale
  sunspot fluxtubes the gas in the small fluxtubes of a few hundred km
  diameter seems to fully participate in the photospheric oscillations
  without any interaction with the magnetic field. Prominence magnetic
  fields show sometimes a reaction to the photospheric 5 min and to the
  chromospheric 3 min oscillations, in addition several other periods
  are found. Indication is found for eigenmodes of Alfvén waves.

---------------------------------------------------------
Title: Periodic and quasiperiodic Doppler velocity variations in
    solar prominences along one spatial direction
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988A&A...204..286B    Altcode:
  Temporal variations of the Doppler displacement of the Hα-emission
  line were measured in four quiescent prominences in autumn 1986 at
  the recently installed Gregory telescope on Tenerife. As detector,
  a 100×100 pixel diode array was used. The length of the time series
  was up to seven hours. The slit was oriented parallel to the solar
  limb in the first case and perpendicular in the others. In November
  1987 another prominence was observed with a 256×256 pixel camera
  simultaneously in Ca<SUP>+</SUP>H and Hɛ over five hours. In this case,
  the slit was oriented parallel to the solar limb. The result for the
  two lines are in good agreement. The authors earlier result of periods
  near one hour is confirmed. Short periods near five and three minutes
  are found in some parts of the prominences. They might be interpreted
  as a reaction of the prominence on the photospheric and chromospheric
  oscillations. For the time series of more than five hours indications
  of eigenmodes of the prominences are found.

---------------------------------------------------------
Title: Spectroscopic analysis of prominence emissions
Authors: Bendlin, C.; Wiehr, E.; Stellmacher, G.
1988A&A...197..274B    Altcode:
  Prominence spectra of fairly high spatial resolution of 3arcsec
  to 4arcsec are analysed. The total optical thickness of the
  Ca<SUP>+</SUP>K emission is determined from the self-absorption
  factor, using the true upper level population obtained from the
  Ca<SUP>+</SUP>8542 emission. Turbulence values determined from the
  widths of optically thin lines show fair agreement with microturbulence
  values obtained from the emission relation of the optically thick
  Ca<SUP>+</SUP>H and K lines. Variations of the emission ratio
  E<SUB>8542</SUB>/E<SUB>&amp;</SUB>beta; in prominences may be related
  to different gas pressures.

---------------------------------------------------------
Title: Spectroscopy of the solar photosphere with high spatial
    resolution
Authors: Wiehr, E.; Kneer, F.
1988A&A...195..310W    Altcode:
  A high-resolution spectrogram from the solar photosphere obtained with
  the recently installed Gregory-Coude telescope at the Canary Islands
  is analyzed. Continuum intensity fluctuations are seen at scales down
  to 0.53 arcsec, which demonstrates the high spatial resolution. Peak
  velocities reach 1.5 km/s, while rms velocities range from 350 to
  490 m/s. It is found that, for deeply-formed spectral lines, shifts
  are well correlated with continuum intensity fluctuations at scales
  between 1.5 and 6 arcsec.

---------------------------------------------------------
Title: Spectrophotometric analysis of small sunspots
Authors: Stellmacher, G.; Wiehr, E.
1988A&A...191..149S    Altcode:
  High resolution spectra of two small sunspots were obtained with the
  Gregory Vacuum Telescope at Izaña (Tenerife) on 1986 Oct. 8 and 9. The
  two lines Fe<SUP>+</SUP> 6149 and Li<SUP>7</SUP> 6707 (doublet) were
  chosen for their very different behaviour in umbra atmospheres. Detailed
  shape analysis shows that cold spot models (T<SUB>eff</SUB> ≅ 4000K)
  cannot explain the present observations; a higher T<SUB>eff</SUB> ≅
  4600K has to be assumed. The influence of parasitic light produced by
  penumbral blurring and the contribution of dots is discussed.

---------------------------------------------------------
Title: Velocity variations of prominences.
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988AGAb....1R..12B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Oscillations in Sunspot Umbra Penumbra and the Surrounding
    Photosphere
Authors: Balthasar, H.; Fangmeier, E.; Kuveler, G.; Wiehr, E.
1988IAUS..123..183B    Altcode:
  Doppler shifts of the nonsplit line Fe I 7090 Å have been measured
  simultaneously in the sunspot umbra, penumbra and the photosphere
  using a 100×100 diode array. The power in the range 2.5 - 4.5 mHz is
  found to decrease from the photosphere towards the umbra. Besides the
  minimum at the center of the umbra, further power minima occur at the
  transition region between umbra and penumbra. No significant power is
  found in the range 5.0 - 6.0 mHz.

---------------------------------------------------------
Title: The Gregory-Coudé-Telescope in the Observatorio del Teide,
    Izaña.
Authors: Kneer, F.; Wiehr, E.; Wittmann, A. D.
1988AGAb....1...46K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Oscillatory motions of the H<SUB>α</SUB>-emission line in
    quiescent prominences.
Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G.
1988dssp.conf...63B    Altcode:
  Temporal variations of the Doppler displacement of the
  H<SUB>α</SUB>-emission were measured in 4 prominences (September 28
  through October 5, 1986) at the recently installed Gregory telescope at
  Tenerife, using a 100×100 pixel diode array. Long periods near one hour
  confirm former results. The amplitude of these long periods vary with
  height and also in the direction parallel to the limb. Short periods
  near 5 minutes and near 3 minutes are found which might be interpreted
  as perturbations by the photospheric and chromospheric oscillations.

---------------------------------------------------------
Title: Oscillations of sunspots in the Stokes-V-inversion point.
Authors: Balthasar, H.; Wiehr, E.
1988AGAb....1Q..12B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic analysis of prominence emissions.
Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G.
1988dssp.conf...67W    Altcode:
  Spatially well resolved prominence spectra of Ca<SUP>+</SUP> and H lines
  are used to determine (1) optical thickness of Ca<SUP>+</SUP>K from
  the self-absorption factor, taking the true upper level population from
  Ca<SUP>+</SUP>8542; (2) turbulence values from the emission relations
  of the thick Ca<SUP>+</SUP>H and K lines yielding results similar to
  those from the widths of optically thin lines; (3) gas pressure from
  the emission ratio Ca<SUP>+</SUP>8542/H<SUB>β</SUB>.

---------------------------------------------------------
Title: The gradient of the small-scale velocity fluctuation in the
    solar atmosphere
Authors: Nesis, A.; Fleig, K. H.; Mattig, W.; Wiehr, E.
1987A&A...182L...5N    Altcode:
  The vertical small-scale velocity gradient in the photosphere is
  determined using spectrograms of high spatial resolution obtained with
  the Gregory-Coude telescope in Izana on August 1, 1986. The measured
  Doppler shifts along the spectrograph slits are analyzed using spatial
  Fourier analysis. The height dependence of the size of the velocity
  fluctuations measured at Doppler velocity is examined. It is observed
  that both the amplitude of the smallest velocity structures and
  the integrated rms small-scale velocity decrease with height in the
  photosphere. The derived rms small-scale velocity values are compared
  with the data of Canfield (1976) and Nesis (1985), and good correlation
  is observed.

---------------------------------------------------------
Title: The gradient of the small-scale velocity fluctuation in the
    solar atmosphere
Authors: Nesis, A.; Mattig, W.; Fleig, K. H.; Wiehr, E.
1987BAAS...19..942N    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A comparison of the oscillations in sunspot umbrae, penumbrae,
    and the surrounding photosphere
Authors: Balthasar, H.; Wiehr, E.; Kueveler, G.
1987SoPh..112...37B    Altcode:
  Time series of the nonsplit FeI 7090 Å line have been observed in
  several sunspots with a 100 x 100 diode array corresponding to 48
  arc sec times 1.39 Å. The spatial behaviour of Doppler motions
  along one fixed slit position has been studied as a function of
  time. Former results are confirmed, that the power in the five minute
  range decreases from the photosphere to the umbra, where, however,
  values still well above the noise level are measured. Regarding the
  penumbra, the power tends to exhibit a maximum at locations where
  the line-of-sight component of a radial horizontal field should
  be maximal. This indicates that the direction of the oscillatory
  velocities might be influenced by the magnetic field or the Evershed
  flow. No significant power is found in the 3 min range. An exception
  might be seen in a small patch at the limb of the umbra of one spot.

---------------------------------------------------------
Title: Shifts of the Circular Zeeman Profile in Small Solar Fluxtubes
Authors: Wiehr, E.
1987LNP...291...54W    Altcode: 1987csss....5...54W
  No abstract at ADS

---------------------------------------------------------
Title: Spectroscopic Analysis of Prominence Emissions
Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G.
1987dssp.work...67W    Altcode: 1987ASSL..150...67W
  No abstract at ADS

---------------------------------------------------------
Title: Needs and Limits of Magnetic and Velocity Field Measurements
    with Sub-Arcsecond Resolution
Authors: Wiehr, E.
1987rfsm.conf...93W    Altcode:
  It is possible to deduce information about magnetic and velocity
  fine structures far below one arcsec even with a relatively small
  instrument. The author discusses methods of observation of fine
  structures of sunspots and solar faculae.

---------------------------------------------------------
Title: Construction of the German Solar Telescopes at Observatorio
del Teide/Tenerife: The Gregory-Coude Telescope
Authors: Kneer, F.; Schmidt, W.; Wiehr, E.; Wittmann, A. D.
1987MitAG..68..181K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Present and Future Facilities for the Vacuum Gregory Coudé
    Telescope at Izaña
Authors: Wiehr, E.
1987rfsm.conf..354W    Altcode:
  The whole instrumentation had been operated at the Locarno station
  until August 1984 when it was dismantled for a transfer to the Izaña
  site at Tenerife. In the course of that re-installation the telescope
  had been completely overhauled. Instrument description, adjustment
  and optical tests are given.

---------------------------------------------------------
Title: Oscillatory Motions of the H Emission Line in Quiescent
    Prominences
Authors: Balthasar, H.; Wiehr, E.
1987dssp.work...63B    Altcode: 1987ASSL..150...63B
  No abstract at ADS

---------------------------------------------------------
Title: Modelling active region fine structures from observations.
Authors: Wiehr, E.
1987PAICz..66...29W    Altcode: 1987eram....1...29W
  Problems, methods and results are discussed to model fine structures
  of sunspots, plages and prominences from observed data. Two component
  models or other indirect methods are used to deduce model atmosphere,
  magnetic and velocity field within these fine structures.

---------------------------------------------------------
Title: High Resolution Spectroscopy of Sunspot Penumbrae
Authors: Wiehr, E.; Knölker, M.; Grosser, H.; Stellmacher, G.
1987rfsm.conf..162W    Altcode:
  The spatial variation of velocity- and magnetic field within penumbral
  finestructures is investigated from two very highly resolved spectra.

---------------------------------------------------------
Title: Evidence for quasi-periodic Doppler motions in solar
    prominences
Authors: Balthasar, H.; Knoelker, M.; Wiehr, E.; Stellmacher, G.
1986A&A...163..343B    Altcode:
  Observations of Doppler displacements in solar prominences have been
  performed using the Hα emission line. Evidence is found for the
  existence of quasi-periodic line-of-sight velocities in the range of
  2.5 - 4.7 mHz. Former findings of long time variations near one hour
  are confirmed. Possible influences by misguiding and by image motion
  can be excluded. Scattered light from the solar aureola cannot produce
  the observed amplitudes.

---------------------------------------------------------
Title: Geschwindigkeits-Oszillationen in solaren Magnetfeld-Gebieten.
Authors: Wiehr, E.
1986S&W....25..316W    Altcode:
  Solar activity observed in the H-alpha and Ca(+) K lines are
  analyzed. Zeeman profiles are studied in order to evaluate the
  velocity oscillations in the magnetic field; 5-minute oscillations were
  detected. The penumbra and umbra intensities and a power spectrum reveal
  the presence of oscillations in the center of sunspots. The possibility
  of oscillations in the fields of prominences is investigated. Spectra
  displaying the magnetic-field oscillations are provided.

---------------------------------------------------------
Title: The sharp decrease of Evershed effect and magnetic field at
    the outer sunspot border
Authors: Wiehr, E.; Knoelker, M.; Grosser, H.; Stellmacher, G.
1986A&A...155..402W    Altcode:
  Spatially high-resolved spectra of a small split line (g = 0.5) in
  four sunspots at different heliographic angles show that the combined
  effect of line core velocities and line asymmetries (defined as Evershed
  effect) is strongly limited to the sunspot area defined by the continuum
  intensity step. Occasionally observed 'adjoining velocity maxima'
  just outside the sunspot edges are not related to line asymmetries,
  thus indicating a different origin than that of the classical Evershed
  effect. A similar concentration of the very spot area is found for
  the magnetic line broadening of two large split lines. Both results
  indicate that magnetic field and velocity field are sharply restricted
  to the visible sunspot, the often observed smooth discontinuity of
  both quantities are thus considered to be due to seeing.

---------------------------------------------------------
Title: Oszillationen in Sonnenflecken-Umbren, -penumbren und der
    benachbarten Photosphäre
Authors: Balthasar, H.; Fangmeier, E.; Küveler, G.; Wiehr, E.
1986MitAG..65..155B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Asymmetric Stokes-V Profiles in Plages and Enhanced Network
    Regions
Authors: Wiehr, E.
1986ssmf.conf...77W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Stokes-spectro-polarimetry with a two-dimensional diode array.
Authors: Scholiers, W.; Wiehr, E.
1985SoPh...99..349S    Altcode:
  A new apparatus is described which measures the Stokes profiles
  by means of a two-dimensional 100 × 100 detector array. On-line
  data processing allows the immediate visualization of the profiles
  corresponding to several spectral lines observed simultaneously along
  one spatial direction on the solar disk. An improved method for the
  accurate compensation of the telescopic birefringence with a Bowen
  compensator is realized. Three different methods for the investigation
  of fluxtube properties are discussed, based on the analysis of V
  profiles and illustrated by first measurements with the apparatus. Two
  characteristics of V profiles; excess polarization and zero crossing
  wavelength of the V profile show strong spatial variations in plages
  and network indicating different dynamical conditions for individual
  fluxtubes.

---------------------------------------------------------
Title: Observation of Stokes-V Profiles
Authors: Wiehr, E.
1985tphr.conf..176W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Spatial and temporal variation of circular Zeeman profiles
    in isolated solar Ca(+) K structures
Authors: Wiehr, E.
1985A&A...149..217W    Altcode:
  Simultaneous wavelength scans (Delta lambda = 1 A; Delta t = 10 s) of
  the circular Zeeman profile, Stokes-V, and of the intensity profile,
  Stokes-I, are performed in isolated Ca(+) K features near solar disc
  center for the large split line Fe 8468.4 (g = 2.5; chi-ex = 2.2 eV;
  W(lambda) = 128 mA). It is found that the V-profiles are always
  redshifted with respect to the I-profiles indicating a downdraft
  equal to or less than 2 km/s inside the flux-tube with respect to its
  non-magnetic surroundings. Both this redshift as well as the known
  asymmetry of the V-profiles is found to vary largely between the
  12 structures observed. Repeated lambda-scans in one selected Ca(+)
  K feature show large time variation of asymmetry and redshift of the
  V-profile in the sense of a decrease of both quantities within a few
  minutes. This might be a first hint for the existence of a convective
  instability. Simultaneous Doppler measurements of the line flanks
  (I-profile) and of the inversion point V = 0 show that the V-profile
  participates on the photospheric 5 min oscillation.

---------------------------------------------------------
Title: Die deutschen Sonnenteleskope des Observatorio del Teide
    auf Teneriffa.
Authors: Schröter, E. H.; Wiehr, E.
1985S&W....24..319S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Evershed Effect and Magnetic Field in Penumbral Finestructures
Authors: Wiehr, E.; Stellmacher, G.
1985LNP...233..198W    Altcode: 1985hrsp.proc..198W
  A highly resolved penumbra spectrum obtained from the Locarno telescope
  on July 4, 1982 is studied. It is observed that line core shifts are
  predominant in dark spectrum streaks and line asymmetries in bright
  spectrum streaks. The relationship between line widths and continuum
  brightness is investigated. A continuous dependence of these line
  parameters on the continuum brightness is detected; decreasing continuum
  brightness results in increasing line widths. Explanations for this
  increase are discussed. The effect of line widths/brightness variations
  on magnetic field fluctuations in penumbral fine structures is examined.

---------------------------------------------------------
Title: Observation of Stokes V profiles.
Authors: Wiehr, E.
1985MPARp.212..176W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The German solar telescopes at the observatorio del Teide
Authors: Schroeter, E. H.; Soltau, D.; Wiehr, E.
1985VA.....28..519S    Altcode:
  This article gives a survey of the German solar telescope installations
  which are going to be operational in 1985 (Gregory Coudé Telescope)
  and in 1986 (Vacuum Tower Telescope) respectively.

---------------------------------------------------------
Title: Influence of Umbral Dots on Sunspot Models
Authors: Wiehr, E.; Stellmacher, G.
1985LNP...233..254W    Altcode: 1985hrsp.proc..254W
  A photoelectric investigation was conducted of umbrae of different
  brightness in three clean continuum windows at 4365 + or - 1/8, 6305 +
  or - 1/4, and 8089 + or - 1/2. These were conducted simultaneously
  in the 13th, 9th and 7th order of the f = 10 m echelle grating
  spectrograph. It was found that the presence of umbral dots could
  not account for observed differences in umbral brightness. In effect,
  it is proposed that the dots represent a less important additive for
  umbrae of different temperatures.

---------------------------------------------------------
Title: Velocity and asymmetry mapping of sunspots
Authors: Kueveler, G.; Wiehr, E.
1985A&A...142..205K    Altcode:
  Using the two-dimensional diode array system at the Locarno solar
  observatory, velocity and asymmetry maps of several sunspots were
  measured in the photospheric nonsplit 4.2-V line Fe 7090.4. It is
  found that the velocity and asymmetry contours of individual spots
  correspond very well. The Evershed velocity field taken from Doppler
  displacements of the very line core does not show any discontinuity at
  the penumbra borders. Velocity maxima are usually found very close to
  the outer spot border. The largest horizontal velocities are obtained
  at smallest heliocentric angles observed (25 deg), thus indicating a
  very steep velocity increase with depth. From time series of identical
  sunspots a slow temporal development of the Evershed field is seen,
  indicating a time delay with respect to the development of the visible
  spot structure. The vertical upflow needed to feed the observed
  horizontal flux is estimated to be of the order of 20-100 m/s.

---------------------------------------------------------
Title: Measurements of vector fields with a diode array.
Authors: Wiehr, E. J.; Scholiers, W.
1985NASCP2374..153W    Altcode:
  A polarimeter has been designed for high spatial and spectral
  resolution. It consists of a quarter-wave plate alternately operating
  in two positions for Stokes-V measurements; and, resp., an additional
  quarter-wave plate for Stokes-U and -Q measurements. At the spectrum
  plane a 100×100 pixel Reticon is used as receiver. The spatial range
  covers 75 arcsec, the spectral window of about 1.8 Å allows the
  simultaneous observation of neighbouring lines.

---------------------------------------------------------
Title: Time-dependence of umbral oscillations
Authors: Soltau, D.; Wiehr, E.
1984A&A...141..159S    Altcode:
  Doppler shifts of the magnetically insensitive line Fe 7090.4 are
  observed in two sunspot umbrae on three days over time intervals up
  to 8.5 h. The temporal power spectra show a large variety of periods
  whose pattern reoccurs periodically. Neither the 300 s nor the 180 s
  periods are preferred umbral modes. Conspicuous power near 0.8 m Hz
  closely corresponds to the known 20 min time scale of umbral dots. A
  240 s period from the revolution of the telescope's RA drive screw
  indicates the occasional existence of a structured umbral velocity
  field; its relation to intensity structures, e.g. the dots, is seen from
  the 240 s power peak in the simultaneously recorded continuum intensity.

---------------------------------------------------------
Title: The gas pressure in solar prominences
Authors: Hellwig, J.; Wiehr, E.; Stellmacher, G.
1984A&A...140..449H    Altcode:
  Attention is given to the results of new measurements of the emission
  relation of Ca(+)8542 and H-beta, which indicate that the emission
  ratio E(Ca/+/8542)/E(H-beta), at about 0.16, is significantly lower
  than the value of about 0.3 obtained by Landsman et al. (1977). The
  presently undertaken comparison of these results with those of the
  Heasley and Milkey (1978) model indicates that a much higher value
  of the gas pressure, approximately 0.1 dyn/sq cm, must be assumed in
  order to match the observed lower ratio.

---------------------------------------------------------
Title: The influence of penumbral fine structures on line profiles
Authors: Wiehr, E.; Koch, A.; Knoelker, M.; Kueveler, G.; Stellmacher,
   G.
1984A&A...140..352W    Altcode:
  An experimental investigation of the effect of penumbral fine structure
  on the line profiles of Ti 5222.7 A and Fe(+) 5264.8 is presented. The
  highly resolved penumbral spectrum was observed with the evacuated
  Locarno telescope of the Goettingen observatory. It is shown that the
  highly excited Fe(+) line has a strong correlation in its line symmetry
  to bright spectrum streaks. Line core shift was correlated with dark
  spectrum streaks. The Doppler shift of the Be(+) line increased by 1.2
  km/s, and that of the Ti line by 0.7 km/s for a continuum brightness
  decrease of 20 percent. On the basis of the observational data, it
  is concluded that the two-component model of sunspot penumbrae is
  unlikely. It is suggested that Evershed asymmetry originates mainly
  from a mixture of fine structure.

---------------------------------------------------------
Title: Oscillations of the Hα Emission in Solar Prominences
Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H.
1984SoPh...94..285W    Altcode:
  The time dependence of Doppler shift and line-center intensity
  is simultaneously observed for the Hα emission of three solar
  prominences, each one during about two hours. Doppler oscillations
  with periods near one hour and amplitudes between 1 and 2 km
  s<SUP>−1</SUP> are conspicuously visible in the recordings of all
  three prominences. Fourier analysis yields periods of 50, 60, and
  64 min, as well as slight indications of short periods near 3 and 5
  min. No oscillations are found in the line-center brightness.

---------------------------------------------------------
Title: Umbral Oscillations Measured in the Stokes-V Inversion Point
Authors: Balthasar, H.; Wiehr, E.
1984SoPh...94...99B    Altcode:
  The inversion point of the circular Zeeman polarization profile
  (V-Stokes) parameter is used to observe umbral Doppler oscillations
  free from disturbing influences of parasitic light. In a second step,
  purely umbral lines are used to avoid remaining influences from the
  V-profile of the (oscillating) penumbra. Among a total of nine sunspot
  umbrae, three exhibit oscillations within the various 1.5 to 2.5 hr
  samples. The periods differ significantly from 300 s, vary with time,
  and occur within time intervals of high tranquility thus explaining
  the lack of oscillations in the remaining sunspots.

---------------------------------------------------------
Title: Geschwindigkeitskartierung von Sonnenflecken
Authors: Küveler, G.; Wiehr, E.
1984MitAG..62..189K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Oszillationen in Flecken-Umbren
Authors: Soltau, D.; Balthasar, H.; Koch, A.; Küveler, G.; Wiehr, E.
1983MitAG..60..225S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Bericht und Programm
Authors: Wiehr, E.
1983MitAG..60..213W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Magnetfeld, Intensität und Strömung in
    Penumbra-Feinstrukturen
Authors: Stellmacher, G.; Wiehr, E.; Knölker, M.
1982MitAG..55...68S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Line profiles and magnetic field in penumbral fine structures
Authors: Stellmacher, G.; Wiehr, E.
1981A&A...103..211S    Altcode:
  Spectra at high spatial resolution are taken in a sunspot penumbra at
  disc center. The magnetic low sensitive lines Fe (+) 5264.8 (g equals
  0.1) and Ti 5222.7 (g equals 0) as well as the large split line Fe
  6302.3 are analyzed by comparison with model calculations. No systematic
  fluctuations of the magnetic field strength and inclination are found
  in the bright and dark spectral streaks, b and d. It is shown that this
  result is still compatible with actual field fluctuations of less than
  or equal to 1,000 G between the individual penumbral bright and dark
  regions, BR and DR. The observed fluctuations of the central intensity
  of the two oppositely temperature sensitive Fe(+) and Ti lines are
  essentially smaller than expected from the continuum fluctuations. The
  DR model requires a larger macro turbulence parameter than the BR model
  in agreement with a spatially low resolved Evershed flow in the DR.

---------------------------------------------------------
Title: On the branching in the emission relations of Ca<SUP>+</SUP>
    in prominences
Authors: Stellmacher, G.; Wiehr, E.
1981SoPh...71..299S    Altcode: 2012arXiv1211.3641S
  Spatially well resolved prominence spectra of the three lines
  Ca<SUP>+</SUP> K, Hβ, and Ca<SUP>+</SUP> 8542 are analysed. It is
  confirmed that the branching in the emission relations of Ca<SUP>+</SUP>
  versus Hβ correlates with the magnitude of non-thermal (turbulent)
  broadening.

---------------------------------------------------------
Title: Umbral Models with Enhanced Continuum Opacity
Authors: Stellmacher, G.; Wiehr, E.
1981A&A....95..229S    Altcode:
  Umbral models based on the assumption of an additional continuum opacity
  (Zwaan, 1974; Kollatschny et al., 1979: M4) are compared with model M3
  by Stellmacher and Wiehr (1975) which is based on the standard continuum
  opacity. <P />The strong Fe 4063.6 lime is observed in several sunspot
  umbrae. An upper limit of parasitic light is estimated on the basis
  of vanishing Fe+ limes in umbrae. It is shown that the wings of the
  so corrected Fe 4063.6 line cannot be reproduced by model M3. The
  recent model M4 requires an opacity enhancement q<SUB>4063</SUB> =
  2.5 ± 0.2; Zwaan's model needs q<SUB>4063</SUB> = 2.7. The relative
  umbral intensity at λλ4063 is obtained to 0.026 I<SUP>phot</SUP>
  using model M4 with q<SUB>4063</SUB> = 2.5. Assuming line haze as
  origin for q<SUB>λ</SUB> the true continuum would amount to 0.065
  I<SUP>phot</SUP>. Measurements of umbral continuum contrasts near
  the peaks of the opacity curve q(λ) suggested by Gaur et al. (1979)
  do not show the marked contrast depressions predicted and are thus
  at variance with the idea that the additional opacity arises from
  electronic transitions of CN, CaB, MgH and TiO molecules.

---------------------------------------------------------
Title: Measurement of solar disc polarization in a number of
    Fraunhofer lines and their adjacent continuum. III - Comparison with
    independent measurements and with calculations
Authors: Wiehr, E.
1981A&A....95...54W    Altcode:
  High-sensitivity measurements of resonance line polarization in
  the Sr(+) 4078, Sr 4607, Ba(+) 4554, Na D2, Mg b, Fe 4063 and Cr
  4275 lines of the solar disk are presented in an attempt to resolve
  discrepancies between previous measurements (Wiehr, 1975, 1978) and
  the data of Stenflo et al. (1980). The present observations were made
  with the Locarno polarimeter improved by the insertion of a new KDP
  crystal having double transmission and double modulation amplitude
  to increase spectral resolution. The F3 4063.6 line is found to show
  resonance polarization, whereas Cr 4274.8 requires further observations
  to establish the possible presence of polarization. The present results
  for Ba(+) 4554 and Sr 4607 agree with both sets of previous results,
  however an excess polarization is observed in the blue wing rather than
  the red for Sr(+) 4087, in agreement with Wiehr (1975); the double
  reversal found by Stenflo et al. in the Na D2 core has also not been
  observed. Finally, the center-to-limb variation of the polarization
  maximum in the blue wings of Ca 4227 and Na D2 given by Wiehr (1975)
  are shown to yield different damping parameters when fitted to the
  calculations of Auer et al. (1980) than those deduced from the data
  of Stenflo et al.

---------------------------------------------------------
Title: Zusatz-Opazität für Sonnenflecken und späte Sterne
Authors: Wiehr, E.; Kollatschny, W.; Stellmacher, G.
1981MitAG..52..162W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Solar observations at the Göttingen University Observatory
Authors: Wiehr, E.; Wittmann, A.; Wöhl, H.
1980SoPh...68..207W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Erratum - Evidence for a Lower Limit of Solar Magnetic Field
    Strengths
Authors: Wiehr, E.
1980A&A....91..377W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The infrared Ca/+/ lines in sunspot umbrae
Authors: Kollatschny, W.; Wiehr, E.; Stellmacher, G.; Falipou, M. A.
1980A&A....86..245K    Altcode: 2012arXiv1210.3336K
  We present an empirical working model for sunspot umbrae which equally
  describes observed continuum intensities and line profiles. The wings
  of the infrared Ca II lines depend sensitively on the temperature
  gradient at -0.6 &lt; log(tau-0.5) &lt; +0.3 but not essentially on
  the absolute value of T. These lines are observed to remain almost
  unchanged from photosphere to umbra and are thus insensitive to
  parasitic light. It is also shown that the infrared K I 7699 line is
  suitable for umbral spectroscopy since it is not seriously blended, its
  continuum is well defined and it is less influenced by parasitic light
  as compared to lines in the visible spectrum, due to the smaller umbral
  contrast. Calculations show that the umbral gradient dT/d(tau), required
  to fit the Ca II triplet lines, strongly conflicts with the observed
  profiles of K I 7699, NaD2 and Fe I 5434 (g=0), even when assuming
  vanishing Fe II lines for a maximum correction of parasitic light. It
  is shown that this discrepancy from the different line profiles may
  be removed by adopting an opacity enhancement as introduced by Zwaan
  (1974) from a discussion of continuum contrasts alone. The finally
  proposed umbral working model is very close to a scaled model of the
  quiet sun with T(eff)= 4000 K thus resembling a M0 rather than a K5
  stellar atmosphere

---------------------------------------------------------
Title: Die Temperatur-Schichtung in Sonnenflecken.
Authors: Wiehr, E.
1980S&W....19..172W    Altcode:
  Various mechanisms to explain the lower temperature of sunspots in
  relation to their surroundings are considered. The investigation of the
  physical characteristics of sunspots is significant for other aspects
  of solar research, as in the determination of the frequency of easily
  ionized elements (e.g., Li, Be, B, and Cs). The recent development of
  methods that permit the measurement of individual linear profiles in
  the umbra of the sunspots is examined, along with the falsification of
  spectra through stray light interference from the surroundings. The
  use of an additional absorber effective at lower temperatures of the
  umbra is discussed.

---------------------------------------------------------
Title: The influence of spatial resolution on the Ca/+/K line width
    and shift in a quiescent prominence
Authors: Engvold, O.; Wiehr, E.; Wittmann, A.
1980A&A....85..326E    Altcode:
  A series of 17 spectrograms of the Ca<SUP>+</SUP> K line in a large
  quiescent prominence are investigated for the effects of spatial
  smearing due to seeing. It is found that the full width at half- maximum
  (FWHM) decreases from 0.190 Å to 0.125 Å when the spatial resolution
  increases from 15" to about 2". High spatial resolution also facilitates
  the detection of large line shifts Δλ. The narrowest line profiles -
  which are detected in the case of high spatial resolution and large
  shift - yield FWHM<SUB>min</SUB> ≍ 0.090 Å, which exceeds the
  pure thermal broadening width by a factor of 2-3. The most probable
  value of the resolved macroscopic velocity is found to be 23 km
  s<SUP>-1</SUP>. This velocity corresponds to an equipartition magnetic
  field strength of about 3.8 G.

---------------------------------------------------------
Title: Line shifts and asymmetries in sunspot penumbrae
Authors: Stellmacher, G.; Wiehr, E.
1980A&A....82..157S    Altcode:
  The paper considers the line shifts and asymmetries in sunspot
  penumbrae. Spatially unresolved spectra show decreasing shifts of
  line cores and increasing symmetries with height; it is shown that
  a decomposition of the asymmetric profiles into a main component and
  a satellite yields contradictory results when considering the depth
  dependence and the center-to-limb variation of different lines. Line
  profiles from the bright and dark spectral streaks are analyzed, showing
  that line widths, residual intensities, and asymmetries increase with
  increasing line shift. Finally, an attempt is made to simulate the
  bright and dark line profiles by simple superposition of intrinsic
  profiles from the bright and dark penumbral regions calculated with
  the corresponding models given by Kjeldseth-Moe and Maltby (1974).

---------------------------------------------------------
Title: Reconstruction of the Locarno Telescope before shifting to
    the Canary Islands site
Authors: Wiehr, E.; Wöhl, H.
1980fsoo.conf...63W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A common model for solar filigree and faculae.
Authors: Stellmacher, G.; Wiehr, E.
1979A&A....75..263S    Altcode:
  A disk-center filigree model for facular plages is examined by
  using photographic spectra of solar lines with a reasonably small
  Zeeman splitting. The results fully confirm previously reported line
  weakenings as well as a previously observed decrease in the line
  weakenings toward the limb. It is found that the highly excited lines
  of Fe II at 5264 A, Ti II at 4568 A, and Si I at 6145 A exhibit line
  strengthenings for most limb faculae but that the absolute intensities
  of the line cores are always higher than those of the neighboring
  photosphere. Photoelectric measurements of the wavelength dependence of
  the contrast in true continuum windows and in facular spectra obtained
  at various heliocentric angles reveal that the contrast decreases with
  wavelength, as reported earlier.

---------------------------------------------------------
Title: Evidence for a lower limit of solar magnetic field strengths.
Authors: Wiehr, E.
1979A&A....73L..19W    Altcode:
  Magnetograph observations of the solar quiet network at the disk center
  with a 4-arcsec aperture are reported. The results obtained for 37 Ca
  II K features indicate a lower limit of 20 G for the solar magnetic
  fields. A lower limit of 2.4 x 10 to the 18th Mx is placed on the
  magnetic flux. A true diameter of 390 to 550 km is estimated for the
  smallest flux tubes, and a field threshold of 200 G is determined for
  pores. The results are compared with previous observations.

---------------------------------------------------------
Title: Ein Modell für solare Filigrees und Fackeln
Authors: Wiehr, E.; Stellmacher, G.
1979MitAG..45..149W    Altcode:
  Previous measurements of magnetically nonsplit lines are extended to
  slightly magnetically split lines to gather data on low ionization
  lines of Fe(+), Ti(+), and Si. Attention is given to Schmahl's model
  in determining the rest-intensity effect, as well as to correlations
  between solar filigrees and faculae.

---------------------------------------------------------
Title: Reconstruction of the Locarno telescope before shifting to
    the Canary Islands site.
Authors: Wiehr, E.; Wöhl, H.
1979MmArc.106...63W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Unique Magnetic Field Range for Nonspot Solar Magnetic
    Regions
Authors: Wiehr, E.
1978A&A....69..279W    Altcode:
  Summary. The `line-ratio method' for simultaneous Zeeman polarization
  in different lines (Stenflo, 1973) has been modified: A) By using the
  3 temperature-insensitive Fe-lines at 6302.5, 6336.8 and 6408.0 A,
  with constant exit slits. B) By measuring Fe 6173.3 simultaneously
  with 3 different exit slits. Difficulties in the data reduction found
  for Case A are less important for Case B. Both methods yield true
  field strengths 1500&lt; rue &lt;2200 Gauss equally for Ca + K bright
  points, H -faculae, pores in plages and pores in spot groups; assuming
  `rectangular field shapes'. A simple evaluation of the `integrated'
  true diameters gives (t)true [km] 65 (Happ [Gs]) , indicating that
  apparent field strengths are almost a measure of diameter rather than
  of field strengths of the magnetic regions. The different features
  observed are characterized by different diameters rather than different
  Htrue Double polarity features do not show a different behaviour
  as compared to single polarity features. No indication is found for
  quantization offluxes or diameters. Simultaneous measurements of the
  central intensity of Ca+ 8498 and the circular polarization in Fe
  8514 show for a considerable part of the magnetic regions (i. e. 11
  among 32) westward displacements of the magnetic field relative to
  the Ca+ feature. This might indicate field inclinations caused by
  faster rotation of the deeper layers. Key words: small scale - field
  strengths - field diameters - field inclination - field displacement

---------------------------------------------------------
Title: Measurement of solar disk polarization in a number of
Fraunhofer lines and their adjacent continuum. II: Improved data,
    new line measurements.
Authors: Wiehr, E.
1978A&A....67..257W    Altcode:
  Summary. The measuring accuracy of 2 t0- achieved in Paper I has been
  increased to 5 10- by investigating a number of instrumental effects
  which are described. The observations of Paper I were verified under
  these conditions with the result that the -dependence of the continuum
  polarization is actually flatter than given in Paper I; and that the
  line polarization of NaD2 and Ba+ 4554 has to be corrected. Furthermore,
  line polarization has been detected in the resonance lines of
  neutral Ba and Sr at 5535 and 4608, respectively. A number of lines
  do not show resonance polarization in contradiction with theoretical
  predictions. Key words: solar disc polarization - resonance polarization

---------------------------------------------------------
Title: Magnetfeld-Feinstrukturen auf der Sonne.
Authors: Wiehr, E.
1978S&W....17..162W    Altcode:
  Current investigations of fine structure of the magnetic field on
  the sun are reviewed. Mention is made of two remarkable discoveries:
  (1) the observation of filigrees in the H-alpha wing by Dunn (1973),
  and (2) the discovery by Stenflo (1973) of small regions of less than
  100-km diameter with magnetic field strengths of around 2000 gauss. The
  principles of three-slot magnetography are reviewed.

---------------------------------------------------------
Title: Zur Existenz einer unteren Grenze solarer Magnetfelder
Authors: Wiehr, E.
1978MitAG..43..134W    Altcode:
  Certain problems regarding the determination of the actual field
  intensities with the aid of simultaneous Zeeman polarimetry in three
  lines can be overcome by using a procedure based on Zeeman polarimetry
  in a single line with three slits of differing widths. The results
  obtained with this procedure confirm results reported by Stenflo
  (1973). The results obtained by three independent methods show that even
  very weak solar fields lie in reality near the 2000 Gauss region. No
  significant differences could be observed between quiet and active
  networks, and facula and sunspot pores.

---------------------------------------------------------
Title: Reconstruction of the Locarno Telescope before shifting to
    the Canary Islands site
Authors: Wiehr, E.; Wöhl, H.
1978fsoo.conf...63W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Das Sonnen-Observatorium der DFG bei Locarno.
Authors: Spindler, R.; Wiehr, E.
1978S&W....17..117S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Zum Problem der Evershedströmungen in Penumbra-Feinstrukturen
Authors: Wiehr, E.; Stellmacher, G.; Soltau, D.
1977MitAG..42..117W    Altcode:
  The use of a two-flow model in the interpretation of the solar
  Evershed flows reported by Schroeter (1965) leads to contradictions
  with respect to recent measurements regarding the flow characteristics
  in the penumbra fine structures. Stellmacher and Wiehr (1971) have
  found in an analysis of line asymmetries based on such a model that
  the line main component must be related to slow-flowing bright penumbra
  structures. The line satellite, on the other hand, must be related to
  fast-flowing dark penumbra structures. A series of nonsplitting lines
  in two long-term individual spots were recorded in connection with a
  more detailed investigation of this model concept. The asymmetrical
  penumbral line profiles were decomposed with the aid of a computer
  calculation into a main component and a satellite. The significance of
  the results is discussed. It is found that the observational phenomena
  can be very well reconciled with a depth-dependent flow concept for
  the penumbra proposed by Maltby (1964).

---------------------------------------------------------
Title: Limb polarization in spectral lines and the continuum.
Authors: Wiehr, E.
1977ROLun..12...89W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Some comments on the measurement of small scale strong magnetic
    fields on the sun.
Authors: Wiehr, E.
1977IAUS...62..251W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Erratum; The Deep Layers of Sunspot Umbrae
Authors: Stellmacher, G.; Wiehr, E.
1976A&A....47..479S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Messung von Magnetfeldern mit Durchmessern unterhalb des
    Seeing-Scheibchens
Authors: Wiehr, E.
1976MitAG..40..163W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ein empirisches Modell für die tiefen Umbra-Schichten
Authors: Wiehr, E.; Stellmacher, G.; Schleicher, H.
1976MitAG..38..217W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The deep layers of sunspot umbrae.
Authors: Stellmacher, G.; Wiehr, E.
1975A&A....45...69S    Altcode: 2012arXiv1210.4393S
  We model the deepest observable layers of dark sunspot umbral
  atmospheres in terms of an empirical model which equally describes
  observed near infrared continuum intensities and line profiles. We
  use the umbral continuum intensity at 1.67 nm and the three C I
  lines at 1,6888, 1,7449 and 1,7456 nm to model the deep layers near
  the minimum of H- absorption. We find that a radiative equilibrium
  stratification yields the best compromise between continuum and C I line
  observations. We determine the effective temperature from the umbral and
  photospheric flux ratio by down-scaling the monochromatic photospheric
  flux with the umbral contrast for each frequency. The thus obtained
  monochromatic umbral flux and the photospheric one are integratied
  over the whole frequency range, yielding the ratio of total umbral and
  photospheric flux, which gives 3560 K &lt; T_eff &lt; 3780 K. We assume
  for our model M3 T_eff=3750 K and fit M3 to the theoretical model by
  Meyer et al. (1974). Comparison of the model's 'nabla' gradient with
  the adiabatic one shows that umbral convection, if existing at all,
  can only occur at considerably deeper layers than in the photosphere.

---------------------------------------------------------
Title: Zum Problem des Kontinuum-Kontrastes solarer Fackeln
Authors: Wiehr, E.; Stellmacher, G.
1975MitAG..36..148W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Measurement of solar disc polarization in a number of
    Fraunhofer lines and their adjacent continuum.
Authors: Wiehr, E.
1975A&A....38..303W    Altcode:
  Summary. The linear polarization in the absorption lines Sr+ 4077,
  Ca 4227, Ba+ 4554, Mgb1,2,3 and NaD1,2, including their adjacent
  continua, is measured at a limb distance of 5 arcsec. In addition, the
  polarization of the violet wings of Ca 4227 and NaD2 as well as that
  of the continua close to these two lines is measured as function of
  the heliocentric angle . Key words: solar disc polarization resonance
  polarizati on

---------------------------------------------------------
Title: On the Solar Magnetic `Monopole'
Authors: Stix, M.; Wiehr, E.
1974SoPh...37..493S    Altcode:
  A superposed epoch analysis shows that the Sun's spurious magnetic
  monopole varies like the solar declination. This indicates that the
  monopole is caused by instrumental effects.

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. VII: A New Zeeman
    Polarimeter and its Advantages as Compared to Other Designs
Authors: Wiehr, E.
1974SoPh...35..351W    Altcode:
  A new modulation procedure for Zeeman polarimeters is described and
  tested. The azimuth rotation by means of two steady λ/4-plates,
  combined with the common EOLM, has several advantages as compared
  to `two-EOLM-polarimeters'. The new polarimeter operates with two
  λ/4-plates which are alternately passed through the beam in front
  of the EOLM by means of an electro-mechanical chopper. The exact time
  of the λ/4-plate change is monitored by a photoelectric sensor. The
  obtained signals drive a number of relays by use of an intervening
  bistable electronic device. These relays allow to cut-off the erroneous
  Doppler signal mode and they furthermore distribute the U and Q signals
  into the corresponding lock-in amplifiers. As a first application of
  the new polarimeter, the linear polarization is measured in a sunspot
  penumbra. The telescope was first compensated for instrumental linear
  polarization down to ≲ 5 × 10<SUP>-4</SUP> by means of a tilted
  glass plate and well as for phase retardation down to ≲ 1° by means
  of a Bowen compensator.

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. VI: Experimental
Compensation of Telescopic Phase Retardation: Influences on Zeeman
    Polarimetry
Authors: Wiehr, E.; Rossbach, M.
1974SoPh...35..343W    Altcode:
  Phase retardation caused by the Grégory-Coudé telescope at Locarno is
  determined empirically and compared with calculations. Good agreement
  is found for a proper retardation angle Δ = 16° for each of the two
  plane mirrors in the telescope.

---------------------------------------------------------
Title: Zur Eliminierung teleskopischer Einflüsse auf Polarimetrie
Authors: Wiehr, E.
1974MitAG..35..209W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Facula Model and its Application to Facula Fine Structures
Authors: Wiehr, E.; Stellmacher, G.
1974IAUS...56..179W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Observed Facula Line Profiles and Contrasts, Comparison
    with Models
Authors: Stellmacher, G.; Wiehr, E.
1973A&A....29...13S    Altcode:
  Summary. Profiles of magnetically insensitive lines are measured
  together with contrasts in real continuum windows for solar facula
  regions at different positions on the disc with a spatial resolution
  of about 3". The contrast measurements earlier observations (Fig. 1);
  the line profiles show the "rest-intensity effect" (discussed in a
  previous paper) to decrease towards the limb (Fig. 2). Calculations
  with a number of reasonable facula models indicate that a homogeneous
  LTE model fails to represent simultaneously the observed contrasts
  and line profiles, without further assumptions. Key words: facula models

---------------------------------------------------------
Title: Observatino of an Instability in a "Quiescent" Prominence
Authors: Stellmacher, G.; Wiehr, E.
1973A&A....24..321S    Altcode: 2012arXiv1210.6779S
  Summary. A cavity-like instability has been observed in a"quiescent"
  prominence. -yaw pictures (Fig. 1) are shown together with Ca+ 8542
  spectra (Fig. 2) taken with an image intensifier. The instability
  propagates almost with the phase velocity of MHD compres sive waves. A
  violation of the lateral stability criterion in the Kippenhahn-
  model is indicated, producing a material outflow along the lines of
  force. Key words: prominences - magnetic instability

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Title: Protuberanzen-Spektroskopie hoher Auflösung mit Hilfe des
    Bildverstärkers
Authors: Stellmacher, G.; Wiehr, E.
1973MitAG..32..166S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Working Model for Sunspot Umbrae
Authors: Stellmacher, G.; Wiehr, E.
1972A&A....19..293S    Altcode:
  Comparison of magnetically non-split line profiles with the predictions
  of several umbra models (Stell macher and Wiehr, 1970) resulted in
  the selection of three "best umbra models", those by Zwaan, Henoux
  and Stellmacher-Wiehr. These models have now been tested by the
  much stronger criterion of the center-to-limb variation (CLV) of the
  non-split line Fe 5434.5 and the Na D-lines. The Stellmacher-Wiehr
  model best represents these observations. This model is thus able to
  simultaneously represent the observations of wavelength dependence
  and CLV of umbra continuum contrasts, the profiles of non-split lines
  including their CLV, and the Na D-lines. This model is proposed as
  a "working model" for reductions of umbra observations. Key words:
  umbra of line proflles in umbrae

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. V. The Magnetic Field
    before and after a Flare
Authors: Wiehr, E.
1972SoPh...24..129W    Altcode:
  High resolved magnetograms (≈ 3″) were obtained 3 hrs before and
  1 hr after a 1b flare, respectively, the only bright flare reported
  for that active region. Careful comparison between both magnetograms
  shows that the line-of-sight component of the active region magnetic
  field remains constant. In particular there is no simplification
  of the rather complicated field structure in connection with the
  flare. Magnetic flux and field gradients also do not show any variation
  above the 3″ scale. Essential changes, however, were observed after
  19 hrs without flare activity. This indicates that evolutionary field
  changes predominate over `flare related' variations.

---------------------------------------------------------
Title: Zeeman Splitting in Some Bright Prominences
Authors: Wiehr, E.
1972A&A....18...79W    Altcode:
  The Zeeman splitting of the Mg b2, Na D2 and Ca+ 8M2 lines in
  several bright prominences has been determined photographically with
  A/4 plate and Wollaston prism. Application of an image intensffier
  allowed exposure times of the order of a few seconds in spite of high
  spectral resolution of about 3.5- 10 . The resulting field strengths
  do not exceed significantly the error limits of 150 Gauss in agreement
  with previous polarimetric measurements. The recently reported strong
  prominence magnetic fields of H 1500 Gauss measured photographically
  with low resolution and without image intensffier have not been
  observed. Key words: prominence magnetic fields

---------------------------------------------------------
Title: The Influence of the Sunspot Model on the Li-Abundance
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...21...96S    Altcode:
  The dependence of the Li-abundance on the equivalent width of the
  Li-resonance doublet at λ 6708 Å is calculated for different umbral
  models. The choice of the model strongly influences the deduced
  Li-abundance (up to a factor 8 or Δ log ɛ<SUB>Li</SUB> = 0.9) even
  when using recent umbral models. Detailed discussion of the observations
  and reduction with the most suitable umbral model (Stellmacher and
  Wiehr, 1970) leads to an abundance of log ɛ<SUB>Li</SUB> = 1.1±0.05
  (in the log ɛ<SUB>H</SUB> = 12.0 scale).

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. IV: Influence of
    Telescopic Phase Retardation
Authors: Wiehr, E.
1971SoPh...18..226W    Altcode:
  Phase retardation originating in a telescope is measured by means of
  polarizer and analyzer. The amount of this retardation depends only
  on the declination δ of the telescope. The retardation axes rotate
  with the Coudé image.

---------------------------------------------------------
Title: Magnetically Non-Split Lines in Faculae
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...18..220S    Altcode:
  Profile changes of five magnetically non-split lines going from the
  photosphere to faculae are investigated. The observations show that
  the profiles normalized to the continuum differ from those of the
  undisturbed photosphere only in the core. The outer parts of the
  profiles remain unchanged. Calculations using two recent facular
  models do not represent these observed profile changes. It is shown
  that a temperature increase in outer layers h≳ 250 km does explain
  the observations. The problem of photospheric magnetograph calibration
  for facula magnetic field measurements is discussed.

---------------------------------------------------------
Title: Magnetically Non Split Lines in Penumbrae
Authors: Stellmacher, G.; Wiehr, E.
1971SoPh...17...21S    Altcode:
  Line asymmetries of five magnetically insensitive lines in penumbrae
  are investigated in detail.

---------------------------------------------------------
Title: On the Circular Polarization in Active Regions
Authors: Wiehr, E.
1971IAUS...43..235W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Difficulties in the Simultaneous Measurement of all Stokes
    Parameters
Authors: Wiehr, E.
1971IAUS...43...89W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. III: Circular
    Polarization in Different Lines; Development of Magnetic Fields.
Authors: Wiehr, E.
1970SoPh...15..148W    Altcode:
  Measurements of the circular polarization V in different lines show
  that the deduced magnetic field strength and flux are systematically
  influenced by variations of the line absorption coefficient from
  photosphere to spot and faculae.

---------------------------------------------------------
Title: Magnetically Non Split Lines in Sunspots
Authors: Stellmacher, G.; Wiehr, E.
1970A&A.....7..432S    Altcode:
  Three magnetically non split lines are measured photographically
  in sunspot umbrae and penumbrae by means of &amp; "spot contrast
  discriminator", which is described and tested. The origin of parasitic
  light is investigated in detail, its upper limit is determined by means
  of a non split Fe+ line being absent in umbrae. These observational data
  are compared with calculations for six umbra models and one penumbra
  model. Concerning the wavelength dependence and the center-to-limb
  variation of the continuum contrast, the umbra models "Zwaan
  preliminary", "Wittmann.Schr6ter" and " " are in accordance with the
  observations. Concerning the proffles of the three non split lines, the
  models "Zwaan preliminary" and " " show a fairly good agreement, which
  is improved by slight alteration of Henoux's temperature stratffication
  in the outer layers (T0 &lt; 1). From the unchanged non split line Fe
  A 4065.4 the best agreement between observed and calculated umbral
  proffles is obtained with a microturbulent velocity 1 km/s being of
  the same order as the photospheric value from recent works. The good
  agreement between measured and calculated umbral proffles indicates that
  inhomogenities are less important for umbrae than for the photosphere.

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. II: Selection of Lines;
    Interpretation of Polarimetric Data
Authors: Wiehr, E.
1970SoPh...11..399W    Altcode:
  The usefulness of magnetically sensitive iron lines Fe λ5250.2, 6173.3
  and 6302.3 for solar polarimetry is investigated. The line-to-continuum
  absorption coefficient η<SUB>0</SUB> for Fe λ5250.2 depends
  strongly on temperature variations. Thus a photospheric calibration
  of polarimeter signals cannot be used for the different parts of
  an active region. This is also true for the Doppler calibration of
  `longitudinal magnetographs'.

---------------------------------------------------------
Title: Messung von Magnetfeldern auf der Sonne.
Authors: Wiehr, E.
1970S&W.....9...65W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Erratum: On polarimetry in solar active regions. I. The new
    Locarno polarimeter; observing procedures. [Sol. Phys., Vol. 9,
    p. 225 - 234 (1969)].
Authors: Wiehr, E.
1970SoPh...11..172W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On Polarimetry in Solar Active Regions. I: The New Locarno
    Polarimeter Observing Procedures
Authors: Wiehr, E.
1969SoPh....9..225W    Altcode:
  The miscentering by the Doppler compensator of the Locarno polarimeter
  is investigated in detail. It is shown that the linear polarization
  is strongly falsified by this effect which also occurs at the Crimean
  and Izmiran polarimeters.

---------------------------------------------------------
Title: Indium, Rubidium, and Caesium in Sunspots
Authors: Stellmacher, G.; Wiehr, E.
1969ApL.....3...91S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Instrumentelle und technische Neuerungen der Sonnenstation
    Locarno
Authors: Schröter, E. H.; Wiehr, E.
1968MitAG..25..187S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On Lithium in Sunspots
Authors: Wiehr, E.; Stellmacher, G.; Schröter, E. H.
1968ApL.....1..181W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Die Häufigkeiten einiger leichter Elemente abgeleitet aus
    Fleckenspektren
Authors: Stellmacher, G.; Wiehr, E.
1968MitAG..25Q.199S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Zur Eichung von Magnetographensignalen
Authors: Wiehr, E.
1968MitAG..25..188W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Problems in the Interpretation of Polarization Measurements
    in Active Regions
Authors: Wiehr, Eberhard
1968IAUS...35..259W    Altcode:
  No abstract at ADS