222 research outputs found
Two-dimensional photometric analysis of emission lines in quiescent prominences
No full textEmission 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 less than or equal to 1 arc sec. The resulting spatially high-resolution two-dimensional images in H beta, H alpha, 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 H alpha and H beta, 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 H beta, 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 less than or equal to 30% within one prominence may be interpreted in terms of a magnetic field with variations of less than or equal to5%. The brightness distribution in most prominences is not smooth but indicates preferred values, which are interpreted as superpositions of several fine structures
Spatial offsets between lines and continuum in limb faculae
No full textHigh-spatial-resolution spectra of limb faculae show spatial displacements of line cores relative to the adjacent continuum at cos theta <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
Solar prominences with Na and Mg emissions and centrally reversed Balmer lines
No full textWe observed bright solar limb prominences with significant emission
of NaD2 and Mgb2 simultaneously with the Hα, Hβ, HeD3,
He+4685, and the Hesingl 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
[ erg/(cm2 s str)] . The centrally reversed
profiles are well reproduced by semi-infinite models. The source function
reaches S [ erg/(cm2 s str Å)] corresponding
to an excitation temperature K; here, the
optically thickness of Hα amounts . The
line widths of the NaD2, Mgb2, and HeD3 profiles yield kinetic
temperatures K and non-thermal broadening
km s-1
Spectroscopy of solar prominences from space and ground
No full textTwo 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 Hbeta at 4862 Angstrom and Ca II at 8542 Angstrom show no significant spatial variation of their pressure-sensitive emission ratio. Slit spectra of the Ca II 8542 Angstrom and He I 10830 Angstrom lines obtained at the Gregory-Coude telescope yield 8000 K < T-kin < 9000 K and 3 km/s < Vn-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
Spectroscopy of solar prominences simultaneously from space and ground
No full textWe 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 Hbeta 4862 Angstrom and Ca II 8542 Angstrom yields a constant ratio, indicating small spatial pressure variations over the prominence. With the Gregory, simultaneous spectra of Ca II 8542 Angstrom and He I 10830 Angstrom were taken, their widths yielding 8000 K 6 x 10(4) 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 He II emission is more related to the 'cool' lines
MSO894615 Supplemental Material - Supplemental material for Is multiple sclerosis progression associated with the HLA-DR15 haplotype?
No full textSupplemental material, MSO894615 Supplemental Material for Is multiple sclerosis progression associated with the HLA-DR15 haplotype? by Klarissa Hanja Stürner Inessa Siembab Gerhard Schön Jan-Patrick Stellmann Nika Heidari Boris Fehse Christoph Heesen Thomas H Eiermann Roland Martin Binder Thomas MC in Multiple Sclerosis Journal—Experimental, Translational and Clinical</p
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