Author name code: stellmacher ADS astronomy entries on 2022-09-14 author:"Stellmacher, Goetz" ------------------------------------------------------------------------ Title: Velocity Difference of Ions and Neutrals in Solar Prominences Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H.; Bianda, M. Bibcode: 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 ≤ Vmacro(Fe II)/Vmacro(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 ≤ Vmacro(Fe II)-Vmacro(He I) ≤ +0.7 km s-1 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. Title: Evidence for the Two-fluid Scenario in Solar Prominences Authors: Wiehr, E.; Stellmacher, G.; Bianda, M. Bibcode: 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 LOS(Sr II) = 1.22 × V LOS(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 LOS(Sr II) = 1.11 ×V LOS(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 e = 4 × 1010 cm-3, shows no relation with the V LOS 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. Title: The Na I and Sr II Resonance Lines in Solar Prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 2017SoPh..292...83S Altcode: 2017arXiv170502475S We estimate the electron density, ne, and its spatial variation in quiescent prominences from the observed emission ratio of the resonance lines Na I 5890 Å (D2) and Sr II 4078 Å. For a bright prominence (τα≈25 ) we obtain a mean ne≈2 ×1010cm−3; for a faint one (τα≈4 ) ne≈4 ×1010cm−3 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, Tkin and Vnth, required to deduce ne 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 λD/λ0, of Sr II 4078 Å show an excess over those from Na D2 and Hδ 4101 Å, assuming the same Tkin and Vnth. 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 D2. Title: The Electron Density in a Quiescent Prominence Authors: Wiehr, E.; Stellmacher, G.; Bianda, M. Bibcode: 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. Title: Non-thermal line-broadening in solar prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 2015A&A...581A.141S Altcode: 2016arXiv160507923S
Aims: We show that the line broadening in quiescent solar prominences is mainly due to non-thermal velocities.
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.
Results: We find a ratio of reduced widths, ΔλD/λ0, 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: τγ ≤ 0.3, τδ ≤ 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 b2 and Mg 4571 (both from the triplet system) of 1.3 ± 0.1.
Conclusions: The discrepant widths of lines from different atoms, and even from the same atom, cannot be represented by a unique pair [Tkin; Vnth]. Values of Tkin deduced from observed line radiances using models indicate low temperatures down to Tkin ≈ 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. Title: The Temperature of Quiescent Prominences Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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 ΔλD/λ0 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 VD2(1/μ) diagrams correspond to unrealistically high Tkin≥104 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. Title: The Hot Skin of Prominence Structures Authors: Wiehr, E.; Stellmacher, G.; Ramelli, R.; Bianda, M. Bibcode: 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<T_{kin}<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. Title: Helium Emissions Observed in Ground-Based Spectra of Solar Prominences Authors: Ramelli, R.; Stellmacher, G.; Wiehr, E.; Bianda, M. Bibcode: 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 D2 emission is used as a tracer for He II emissions which are sufficiently bright to exceed the noise level near 10−6 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 [ΔλD/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. Title: Balmer and Lyman Emission Lines in Solar Prominences Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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. Title: On the origin of the Balmer and Lyman emission lines in solar prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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.
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.
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 Tb to be estimated from the spectral radiance at line center, where Tb is found to be largely independent of the upper level number, in contrast to the (known) behavior of the Balmer lines. Title: Imaging of the He D3/Hβ Emission Ratio in Quiescent Solar Prominences Authors: Hirzberger, J.; Wiehr, E.; Stellmacher, G. Bibcode: 2007ASPC..368..321H Altcode: Quiescent solar prominences have been observed simultaneously in profile-integrated He D3 and Hβ emission with the SST on La Palma. The two-dimensional ratio maps of the He D3 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. Title: Two-dimensional imaging of the He D_3/Hbeta emission ratio in quiescent solar prominences . Authors: Stellmacher, G.; Wiehr, E.; Hirzberger, J. Bibcode: 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. Title: Two-Dimensional Mapping of the He D3/Hβ Emission Ratio in Solar Prominences Authors: Wiehr, Eberhard; Stellmacher, Goetz; Hirzberger, Johann Bibcode: 2007SoPh..240...25W Altcode: Solar prominences have been simultaneously observed in the integrated light of the He D3 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. Title: Two-dimensional imaging of the HeD3/H[Beta] emission ratio in quiescent solar prominences Authors: Wiehr, E.; Stellmacher, G.; Hirzberger, J. Bibcode: 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. Title: Solar prominences with Na and Mg emissions and centrally reversed Balmer lines Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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>16×{}104 [ erg/(cm2 s str)] . The centrally reversed profiles are well reproduced by semi-infinite models. The source function reaches Sα≤{}36 × {}104 [ erg/(cm2 s str Å)] corresponding to an excitation temperature T_exα≈3950 K; here, the optically thickness of Hα amounts τ^0α≈{}10. The line widths of the NaD2, Mgb2, and HeD3 profiles yield kinetic temperatures 7000≤{}T_kin<8000 K and non-thermal broadening v_tu=5 km s-1. Title: Spectroscopy of Solar Prominences Simultaneously From Space and Ground Authors: Stellmacher, G.; Wiehr, E.; Dammasch, I. E. Bibcode: 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 <Tkin<9000 K and 3<vnth<8 km s−1. 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<1.0 for the fainter prominence but reaches up to τ=2.0 for the brighter one. The τ0 values allow us to deduce the source function from the central line intensities and thus a mean excitation temperature Texmean=3750 K, which determines the relative populations of the helium 3S and 3P 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 Tkin from the ground-based spectra. The level populations along the line of sight follow for 5 lekle a smooth Boltzmann distribution with Tex>6×104 K, the levels k>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: Spectroscopy of solar prominences from space and ground Authors: Dammasch, I. E.; Stellmacher, G.; Wiehr, E. Bibcode: 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 < T_kin < 9000 K and 3 km/s < V_n-th < 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<k<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: Spatial offsets between lines and continuum in limb faculae Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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<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: Two-dimensional photometric analysis of emission lines in quiescent prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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+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+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: Two-dimensional Mapping of Emission Ratios in Quiescent Prominences Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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. Bibcode: 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 Tblue−Tred=220 K and Tir−Tred=−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 Cλ= [Ifac/Iphot] λshow a large scatter around mean values of Cblue/Cred=1.075 and Cir/Cred=0.98. We determined the center-to-limb variation of the 863.5 nm continuum contrast for 0.17>cosθ>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 C550=1.7, which is far higher than previously observed values. The behaviour for cos θ>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: The hot prominence periphery in EUV lines Authors: de Boer, C. R.; Stellmacher, G.; Wiehr, E. Bibcode: 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 <= Tkin <= 8000 K and 2.5 <xi <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: Prominence Emissions with SUMER and Optical Telescopes Authors: Wiehr, E.; Stellmacher, G.; de Boer, C. R.; Sütterlin, P. Bibcode: 1998ASPC..155..331W Altcode: 1998sasp.conf..331W No abstract at ADS Title: About polar ejection events and surges Authors: Loucif, M. L.; Koutchmy, S.; Stellmacher, G.; Georgakilas, A.; Bocchialini, K.; Delaboudinière, J. -P. Bibcode: 1998ESASP.421..299L Altcode: 1998sjcp.conf..299L No abstract at ADS Title: Wave Activity and Prominence Eruption Authors: Baudin, F.; Bocchialini, K.; Delannee, C.; Koutchmy, S.; Stellmacher, G.; Shibata, K.; Veselovsky, I. S.; Panasenko, O. A.; Zhukov, A. N. Bibcode: 1998ASPC..150..314B Altcode: 1998IAUCo.167..314B; 1998npsp.conf..314B 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. Bibcode: 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. Bibcode: 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: The helium singlet-to-triplet line ratio in solar prominences. Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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_/Hbeta_ and Ca^+^8662/Hbeta_ 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: 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. Bibcode: 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: Branching of the helium-to-Balmer emission ratio in solar prominence structures. Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1995A&A...299..921S Altcode: The Halpha_, Hbeta_, 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_/ Hbeta_ and He D_3_/Halpha_ 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 Hα and Hβ emissions in solar prominence structures. Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1994A&A...290..655S Altcode: High precision photometry of the Halpha_ and Hbeta_ 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_(Halpha_)/E_tot_(Hbeta_) 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 Halpha_. Optically thick Halpha_ emissions with central absorptions are spatially related with narrow Hbeta_ emissions and hence with small kinetic temperatures. The narrow Hbeta_ 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: Dependence of the He/H_8_ emission ratio on brightness, temperature, and structuring of prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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: Chromospheric Faculae as Filaments Feet? Authors: Koutchmy, S.; Stellmacher, G. Bibcode: 1994emsp.conf...91K 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. Bibcode: 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: Structural changes in the solar corona during the July 1991 eclipse Authors: Zirker, J. B.; Koutchmy, S.; Nitschelm, C.; Stellmacher, G.; Zimmermann, J. P.; Martinez, P.; Kim, I.; Dzyubenko, N.; Kurochka, L.; Makarov, V. Bibcode: 1992A&A...258L...1Z Altcode: Preliminary results of the analysis of radially filtered pictures obtained at several hours interval during the July 11, 1991 total solar eclipse are given. Instrumental parameters and method are outlined. Structural changes are discussed. Title: Modelling the moustache phenomenon in network regions Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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. Bibcode: 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. Bibcode: 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: The magnetic-field polarity of quiescent prominences Authors: Kim, I. S.; Klepikov, V. Y.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1990PAZh...16..545K Altcode: A statistical analysis of magnetographic data on quiescent solar prominences is presented. The existence of two different magnetic field systems in quiescent prominences is suggested. The first system is oriented opposite to the underlying photospheric field; the angle between the long axis of the filament and the field direction is equal to 15 deg and B-parallel equals 15-18 G. The polarities of the second system and of the underlying photospheric field are the same, B-parallel = 5-7 G. Title: Magnetic Field Polarity of Quiescent Prominences Authors: Kim, I. S.; Klepikov, V. Y.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1990SvAL...16..234K Altcode: No abstract at ADS Title: Doppler Velocity Oscillations in Quiescent Prominences Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G. Bibcode: 1990LNP...363..255W Altcode: 1990IAUCo.117..255W; 1990doqp.coll..255W No abstract at ADS Title: Velocity and magnetic field fluctuations in penumbral fine-structures Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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: Magnetic fields of solar prominences: strength and latitude distribution. Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1989BSolD..11...98K Altcode: According to the data obtained by a Nikolsky-type magnetograph during 1979 - 1986 there are two maxima in histograms "occurrence-B∥": O - 21 G and 27 - 36 G. The probability of the minimum between these maxima is equal to 82%. The first maximum may be divided into three distributions with peaks at 8, 15 and 20 G. The second maximum refers to active latitude prominences. The major part of the data (80%) belongs to the pre-minimum and minimum epochs. For this period the average latitude of prominence formation is less than 20°. The authors believe that the peak at 15 G characterizes the critical field strength of prominence formation. Title: Doppler Velocity Oscillations in Quiescent Prominences Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G. Bibcode: 1989HvaOB..13..131W Altcode: No abstract at ADS Title: Oscillations in presence of local magnetic fields. Authors: Wiehr, E.; Balthasar, H.; Stellmacher, G. Bibcode: 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. Bibcode: 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+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. Bibcode: 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+K emission is determined from the self-absorption factor, using the true upper level population obtained from the Ca+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+H and K lines. Variations of the emission ratio E8542/E&beta; in prominences may be related to different gas pressures. Title: On variation of prominence heights with the solar cycle. Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1988BSolD...5...77K Altcode: The behaviour of prominence heights with the solar cycle is studied. Prominence pictures taken by the Nikolsky magnetograph in 1979 - 1986 are used. A dependence of the average height with time is analysed. The minimum height took place in the fall of 1984, 2 years before the solar activity minimum. Histograms of "prominence occurrence versus height" were constructed for different phases of the solar cycle. It is pointed out that the behaviour of the average prominence height depends on the variation of the distribution of prominence heights with the solar cycle. The minimum height is due to a relative increase of the number of prominences which is less than 25 arcsec. The occurrence of these prominences has a peak before the minimum of solar activity. Such prominences are predominantly located at the latitudes 0 - 20°. Title: Spectrophotometric analysis of small sunspots Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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+ 6149 and Li7 6707 (doublet) were chosen for their very different behaviour in umbra atmospheres. Detailed shape analysis shows that cold spot models (Teff ≅ 4000K) cannot explain the present observations; a higher Teff ≅ 4600K has to be assumed. The influence of parasitic light produced by penumbral blurring and the contribution of dots is discussed. Title: On the distribution of prominence heights. Authors: Kim, I. S.; Klepikov, V. Yu.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1988BSolD1988...75K Altcode: The distribution of prominence heights is studied. Prominence pictures obtained in 1979 - 1986 by the Nikolsky magnetograph are used. Discreteness in the distribution of heights is found. There are two peaks: the first narrow peak at 20 - 25 arc sec and the second one at 35 - 45 arc sec. One finds that the prominences with heights less than 25 arc sec locate mainly at the latitude interval 0 < φ ≤ 20°. During the preminimum and minimum of solar activity the average latitude of the filaments (prominences) formation is 18 - 21°. The most likely height interval for prominence formation is at 20 - 25 arc sec (which is the critical height). Title: Velocity variations of prominences. Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G. Bibcode: 1988AGAb....1R..12B Altcode: No abstract at ADS Title: Oscillatory motions of the Hα-emission line in quiescent prominences. Authors: Balthasar, H.; Wiehr, E.; Stellmacher, G. Bibcode: 1988dssp.conf...63B Altcode: Temporal variations of the Doppler displacement of the Hα-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: Spectroscopic analysis of prominence emissions. Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G. Bibcode: 1988dssp.conf...67W Altcode: Spatially well resolved prominence spectra of Ca+ and H lines are used to determine (1) optical thickness of Ca+K from the self-absorption factor, taking the true upper level population from Ca+8542; (2) turbulence values from the emission relations of the thick Ca+H and K lines yielding results similar to those from the widths of optically thin lines; (3) gas pressure from the emission ratio Ca+8542/Hβ. Title: Some Statistical Properties of the Magnetic Field in Prominences Authors: Kim, I.; Koutchmy, S.; Stellmacher, G.; Stepanow, A. I. Bibcode: 1987rfsm.conf..289K Altcode: Magnetic field observations based on the Zeeman effect, measuring the longitudinal component B∥ of the field with an entrance hole of 6.4 arcsec diameter, were obtained for a great number of prominences during 1979 to 1985. Title: Spectroscopic Analysis of Prominence Emissions Authors: Wiehr, E.; Bendlin, C.; Stellmacher, G. Bibcode: 1987dssp.work...67W Altcode: 1987ASSL..150...67W No abstract at ADS Title: Properties of a Concentrated Magnetic Field Region Authors: Koutchmy, S.; Stellmacher, G. Bibcode: 1987rfsm.conf..103K Altcode: Further results concerning the fine structure of concentrated magnetic field regions or network elements, observed near disk center well outside of active regions, are presented. Title: High Resolution Spectroscopy of Sunspot Penumbrae Authors: Wiehr, E.; Knölker, M.; Grosser, H.; Stellmacher, G. Bibcode: 1987rfsm.conf..162W Altcode: The spatial variation of velocity- and magnetic field within penumbral finestructures is investigated from two very highly resolved spectra. Title: The 1981 total solar eclipse. III - Photometric study of the prominence remnant in the reversing south polar field Authors: Stellmacher, G.; Koutchmy, S.; Lebecq, C. Bibcode: 1986A&A...162..307S Altcode: High resolution white light colour pictures obtained during the 1981 total solar eclipse were used for a photometric analysis of the S-pole region. A small helmet-like streamer was visible over the S-polar limb overlying a faint polar prominence from the polar crown belt of filament channels that reached 87° latitude at the eclipse date. Typical electron densities deduced are ne ≅ 2×109cm-3 for the activated top of the prominence and ne ≅ 6×108cm-3 for the associated coronal structures. Upward velocities up to 160 km s-1 are obtained for the eruptive prominence parts. The authors found that dynamic processes are controlled by magnetic forces for fields B ≥ 3.5 Gauss, and that the coronal structures are apparently connected with the faintest and most dynamic parts of the prominence. Title: Evidence for quasi-periodic Doppler motions in solar prominences Authors: Balthasar, H.; Knoelker, M.; Wiehr, E.; Stellmacher, G. Bibcode: 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: The sharp decrease of Evershed effect and magnetic field at the outer sunspot border Authors: Wiehr, E.; Knoelker, M.; Grosser, H.; Stellmacher, G. Bibcode: 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: Measurement of Magnetic Fields in Solar Prominences Authors: Nikolskii, G. M.; Kim, I. S.; Koutchmy, S.; Stepanov, A. I.; Stellmacher, G. Bibcode: 1985SvA....29..669N Altcode: No abstract at ADS Title: The 1981 total solar eclipse corona. II. Global absolute photometric analysis. Authors: Lebecq, C.; Koutchmy, S.; Stellmacher, G. Bibcode: 1985A&A...152..157L Altcode: Detailed results of the absolute photometry of the solar corona during the July 31, 1981 total eclipse are presented together with a morphological analysis. The basic calibration method uses the detailed photometry of images of stars present on the same coronal picture. Both sky intensity and coronal aureola variations over the field are carefully evaluated. The recent axi-symmetric non-spherical model of the F-corona is introduced and the relevant K-corona intensity variations are derived. The determinations of the Ludendorf index of flattening and the integrated total brightness of the K-corona alone are made and discussed in relation to the phase of the sunspot cycle of activity. Title: Evershed Effect and Magnetic Field in Penumbral Finestructures Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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: Influence of Umbral Dots on Sunspot Models Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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: The gas pressure in solar prominences Authors: Hellwig, J.; Wiehr, E.; Stellmacher, G. Bibcode: 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. Bibcode: 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: Comparative magnetographic observations in different prominence lines Authors: Nikolsky, G. M.; Kim, I. S.; Koutchmy, S.; Stellmacher, G. Bibcode: 1984A&A...140..112N Altcode: 1984A&A...140..112K Analysis of the longitudinal field strength in prominences obtained by measurements of Zeeman polarization in HeD3, Hα, and Hβ is presented. The measurements were performed with the spectrally scanning magnetograph installed at the 53 cm coronograph of the Kislovodsk high altitude station. The observations allow to correlate the values of the equivalent widths and those of the half widths with magnetographic data. No systematic dependence of field strengths on line widths is found. High field strengths persist for large Doppler shifts and low emissions. In the histogram showing the distribution of observed field strengths two peaks near B∥ ≅ 8 Gauss and B∥ ≅ 20 Gauss appear. The second peak corresponds to prominences mainly related to active regions for latitudes <±35°. A similar distribution is obtained from a set of data deduced from observation of the Hanle effect and corresponding to the same epoch. Title: Oscillations of the Hα Emission in Solar Prominences Authors: Wiehr, E.; Stellmacher, G.; Balthasar, H. Bibcode: 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−1 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: The electron density of faint prominences observed during the solar eclipse of July 31, 1981 Authors: Koutchmy, S.; Lebecq, C.; Stellmacher, G. Bibcode: 1983A&A...119..261K Altcode: Prominences visible on the narrow band filtergrams of the eclipsed Sun, July 3t, 1981, are analysed. The ratio of the Hβ line intensity to the continuum intensity at λ=6073 Å is used to derive the electron density ne as a function of electron temperature Te. The prominences present on that day were of low brightness: Eβ,max ≃ 0.2 104 [erg cm-2 s-1 sterad-1]. An electron density ne = 5.7 109 [cm-3] at Te = 10,000° is obtained, being typical for prominence edges. Title: Magnetic field in solar prominences measured with a new spectrally scanning magnetograph Authors: Kim, I. S.; Nikolsky, G. M.; Koutchmy, S.; Stellmacher, G. Bibcode: 1982A&A...114..347K Altcode: Observations of the longitudinal field strength in quiescent prominences obtained with the new redesigned spectrally scanning magnetograph installed in the Coude focus of the 53 cm coronograph of the Kislovodsk station are presented. With the instrument one can obtain magnetographic data as well as central intensities, equivalent widths, line widths, and shifts of the analyzed prominence lines. A first discussion, correlating magnetographic and spectroscopic data, is given Title: Magnetfeld, Intensität und Strömung in Penumbra-Feinstrukturen Authors: Stellmacher, G.; Wiehr, E.; Knölker, M. Bibcode: 1982MitAG..55...68S Altcode: No abstract at ADS Title: Line profiles and magnetic field in penumbral fine structures Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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: Joint Soviet - French Investigations of the Solar Corona - Part Three - Structure and Some Dynamic Features of the Solar Corona of 1973JUN30 Authors: Vsekhsvyatskii, S. K.; Dzyubenko, N. I.; Ivanchuk, V. I.; Popov, O. S.; Rubo, G. A.; Koutchmy, S.; Koutchmy, O.; Stellmacher, G. Bibcode: 1981SvA....25..463V Altcode: No abstract at ADS Title: On the branching in the emission relations of Ca+ in prominences Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1981SoPh...71..299S Altcode: 2012arXiv1211.3641S Spatially well resolved prominence spectra of the three lines Ca+ K, Hβ, and Ca+ 8542 are analysed. It is confirmed that the branching in the emission relations of Ca+ versus Hβ correlates with the magnitude of non-thermal (turbulent) broadening. Title: Joint Soviet / French Investigations of the Solar Corona - Part Two - Photometry of the Solar Corona of 1973JUN30 Authors: Vsekhsvyatskii, S. K.; Dzyubenko, N. I.; Ivanchuk, V. I.; Popov, O. S.; Rubo, G. A.; Koutchmy, S.; Koutchmy, O.; Stellmacher, G. Bibcode: 1981SvA....25..211V Altcode: No abstract at ADS Title: Umbral Models with Enhanced Continuum Opacity Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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.

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 q4063 = 2.5 ± 0.2; Zwaan's model needs q4063 = 2.7. The relative umbral intensity at λλ4063 is obtained to 0.026 Iphot using model M4 with q4063 = 2.5. Assuming line haze as origin for qλ the true continuum would amount to 0.065 Iphot. 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: On TV Observations of Polarization of Green Coronal Line at the Eclipse Time of 1981JUL31 Authors: Popov, O. S.; Ivchenko, V. N.; Lapchuk, V. P.; Milinevsky, G. P.; Osminkina, K. I.; Koutchmy, S.; Begot, J.; Lebeq, C.; Stellmacher, G. Bibcode: 1981ATsir1202....1P Altcode: 1981ATsir1202Q...1P No abstract at ADS Title: Zusatz-Opazität für Sonnenflecken und späte Sterne Authors: Wiehr, E.; Kollatschny, W.; Stellmacher, G. Bibcode: 1981MitAG..52..162W Altcode: No abstract at ADS Title: The infrared Ca/+/ lines in sunspot umbrae Authors: Kollatschny, W.; Wiehr, E.; Stellmacher, G.; Falipou, M. A. Bibcode: 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 < log(tau-0.5) < +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: Line shifts and asymmetries in sunspot penumbrae Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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: A common model for solar filigree and faculae. Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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: Simultaneous measurements of Ca+ K, Ca+ H, Hα, Hβ, and He D3 emission in prominences Authors: Stellmacher, G. Bibcode: 1979SoPh...61...61S Altcode: Simultaneously measured line intensities of Ca+ K and H, Hα, Hβ and He D3 are presented and compared with recent model calculations by Heasley and Milkey (1978). The model calculations are compatible with the observations. There is indication that the observed branching of the relation E(Ca+ K and H) ∼ E(Hβ) depends on the widths of the Ca+-lines. Title: Discussion Authors: Maltby, P.; Stellmacher, G. Bibcode: 1979phsp.coll...35M Altcode: 1979IAUCo..44...35M No abstract at ADS Title: Ein Modell für solare Filigrees und Fackeln Authors: Wiehr, E.; Stellmacher, G. Bibcode: 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: Ca^{+} (h and K), Hα and Hβ Emission Observed Simultaneously in Quiescent Prominences. Authors: Stellmacher, G. Bibcode: 1979phsp.coll...33S Altcode: 1979phsp.conf...33S; 1979IAUCo..44...33S No abstract at ADS Title: Photometrical analysis of the June 30, 1973 solar corona. Authors: Koutchmy, S.; Stellmacher, G.; Koutchmy, O.; Dzubenko, N. I.; Ivanchuk, V. I.; Popov, O. S.; Rubo, G. A.; Vsekhsviatskii, S. K.; Lamy, P. Bibcode: 1978A&A....69...35K Altcode: In order to deduce reliable values of the K and F coronal, a method of photographic photometry has been applied to study compensated high-resolution pictures obtained during the June 30, 1973, solar total eclipse, including a color one. The correctly exposed images of calibration stars are used to obtain intensities in units of the mean brightness of the sun. An account is made, in both the blue and the red spectral ranges, for the sky background as well as for the coronal aureola effects. The N-polar and E-equatorial regions are shown to be relatively homogeneous; their intensities are especially studied in the radial direction and compared with published values of the K and F coronae. No flattening and no color effect are found in the inner part (distance less than 2.5 solar radii) of the F corona. Title: Photospheric faculae. II. Line profiles and magnetic field in the bright network of the quiet sun. Authors: Koutchmy, S.; Stellmacher, G. Bibcode: 1978A&A....67...93K Altcode: Smnmary. Spatially high resolution spectra ( 0"75) of the three iron lines. Fe 5576 A (non split), Fe 6301.5 A and Fe 6302.5 A (triplet) observed in maguetic regions (network) of the quiet Sun, were analysed. For the model computations, recent values of filigree continuum contrast and diameter were used [1f/1P -18, 4) -0"24 (174 km), =6000 A]. High values of the maguetic field strength (10001500 Gauss) are found for the quiet network regions. A fit of the observed profiles with the calculated proffles can be obtained only when a strong maguetic field is also assumed in the intergranular regions that surround the filigrees; the dimension of the magnetic field patch is found to be structured and larger than that of the proper line gap (ffligree). For the model calculations, a good fit is obtained when the filigree width r is assumed to increase with height h as r =0.12 h+87 [km]. Key words: Sun - photo sphere - filigrees - facularpoints - gap-profiles - concentrated magnetic fields Title: The Contrast of Solar Filigrees Authors: Koutchmy, S.; Stellmacher, G. Bibcode: 1977MitAG..42..142K Altcode: No abstract at ADS Title: Zum Problem der Evershedströmungen in Penumbra-Feinstrukturen Authors: Wiehr, E.; Stellmacher, G.; Soltau, D. Bibcode: 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: Photometric study of chromospheric and coronal spikes observed during the total solar eclipse of 30 June 1973. Authors: Koutchmy, S.; Stellmacher, G. Bibcode: 1976SoPh...49..253K Altcode: A photometric and colorimetric analysis of a color picture of the very inner solar corona, near the South pole region, is performed. Dimensions and average electron densities of both chromospheric and very fine resolved coronal spikes are deduced. For the coronal spike a half width of 1″.67 is measured, the estimate of electron density yields ne = 1010 cm−3. Some conclusions are attempted on the light of a simultaneously observed spectrum of the same region which appeared to be a "disappearing coronal hole." The observations seem to support the concept of a "striated" corona. Title: Erratum; The Deep Layers of Sunspot Umbrae Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1976A&A....47..479S Altcode: No abstract at ADS Title: Ein empirisches Modell für die tiefen Umbra-Schichten Authors: Wiehr, E.; Stellmacher, G.; Schleicher, H. Bibcode: 1976MitAG..38..217W Altcode: No abstract at ADS Title: The deep layers of sunspot umbrae. Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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 < T_eff < 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. Bibcode: 1975MitAG..36..148W Altcode: No abstract at ADS Title: Study of low dispersion eclipse spectra: observation of weak low excitation emission lines in the corona. Authors: Stellmacher, G.; Koutchmy, S. Bibcode: 1974A&A....35...43S Altcode: Summary. A spectroscopic experiment, set up to observe simultaneously the electronic, emission line and F-corona, near the equator between 0.1 and 0.8 R0 above the sun's limb, was carried out successfully during the total solar eclipse on June 30, 1973 in the Republic of Tchad. The low excitation line emission in Ca+, H and K, H , H , H is observed superimposed over the entire spectrum, including the lunar background. No radial dependence is observed for the equivalent width of these lines. The emission is interpreted in terms of double scattered light of chromospheric origin in the earth's atmosphere. The color dependence of the double scattered light is correctly reproduced by a quasi quantitative model confirming the parasitic origin of these lines. Key words: sun - total solar eclipse chromospheric emission lines double scattered parasitic light atmospheric optics Title: Sur les premiers signes de la reprise de l'activité solaire. Authors: Koutchmy, S.; Bareau, C.; Stellmacher, G. Bibcode: 1974CRASB.278..873K Altcode: No abstract at ADS Title: A Facula Model and its Application to Facula Fine Structures Authors: Wiehr, E.; Stellmacher, G. Bibcode: 1974IAUS...56..179W Altcode: No abstract at ADS Title: Observed Facula Line Profiles and Contrasts, Comparison with Models Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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. Bibcode: 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 Title: Protuberanzen-Spektroskopie hoher Auflösung mit Hilfe des Bildverstärkers Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1973MitAG..32..166S Altcode: No abstract at ADS Title: On the Line Intensity Ratios E(Hα)/ E(D3) and E(Hβ)/ E(D3) in Prominences Authors: Stellmacher, G. Bibcode: 1972SoPh...25..104S Altcode: The intensity ratios E(Hα)/E(D3) and E(Hβ)/E(D3) in prominences depend on the total optical thickness in Hα of the layer. The emission of the He D3 line appears relatively enhanced in thin layers and in outer parts of the prominences. Title: A Working Model for Sunspot Umbrae Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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: The Influence of the Sunspot Model on the Li-Abundance Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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 ɛLi = 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 ɛLi = 1.1±0.05 (in the log ɛH = 12.0 scale). Title: Magnetically Non-Split Lines in Faculae Authors: Stellmacher, G.; Wiehr, E. Bibcode: 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. Bibcode: 1971SoPh...17...21S Altcode: Line asymmetries of five magnetically insensitive lines in penumbrae are investigated in detail. Title: Magnetically Non Split Lines in Sunspots Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1970A&A.....7..432S Altcode: Three magnetically non split lines are measured photographically in sunspot umbrae and penumbrae by means of & "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 < 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: Indium, Rubidium, and Caesium in Sunspots Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1969ApL.....3...91S Altcode: No abstract at ADS Title: Spectroscopic Analysis of Faint Prominences Authors: Stellmacher, G. Bibcode: 1969A&A.....1...62S Altcode: The following results were obtained from a spectroscopic analysis 9f faint prominences: kinetic temperature from linewidths: 6000 - 7000 K; turbulent velocity = 5 km s-1 electron density ne = 3. 1010 cm- . For all observed prominences a common state of excitation was found with considerable departures from L.T.E. For the H atom, these departures are characterised by = 40, b5,3 = 2, bs.b = 1 (k 4). The higher levels of the H atom and He atom are found to be in equilibrium with the free electrons at a temperature Te = 6000-6250 K. The Balmer decrement gave EH/E = 12 (after correction for sell-absorption). For the 3 8D level of He is found `D = 1.25. The populations of the 3 8D level and the third level (0,3) of the H atom are influenced by resonance-scattering of the visible photospheric radiation. Title: On Lithium in Sunspots Authors: Wiehr, E.; Stellmacher, G.; Schröter, E. H. Bibcode: 1968ApL.....1..181W Altcode: No abstract at ADS Title: Die Häufigkeiten einiger leichter Elemente abgeleitet aus Fleckenspektren Authors: Stellmacher, G.; Wiehr, E. Bibcode: 1968MitAG..25Q.199S Altcode: No abstract at ADS Title: Spektroskopische Analyse einiger schwacher Protuberanzen Authors: Stellmacher, G. Bibcode: 1968MitAG..25..190S Altcode: No abstract at ADS