منابع مشابه
An investigation of Fe emission lines in solar flare spectra
Previously, large discrepancies have been found between theory and observation for Fe emission line ratios in solar flare spectra covering the 224–327 Å wavelength range, obtained by the Naval Research Laboratory’s S082A instrument on board Skylab. These discrepancies have been attributed to either errors in the adopted atomic data or the presence of additional atomic processes not included ...
متن کاملAn investigation of Fe XVI emission lines in solar and stellar EUV and soft X-ray spectra
New fully relativistic calculations of radiative rates and electron impact excitation cross sections for Fexvi are used to determine theoretical emission-line ratios applicable to the 251–361 Å and 32–77 Å portions of the extreme-ultraviolet (EUV) and soft X-ray spectral regions, respectively. A comparison of the EUV results with observations from the Solar Extreme-Ultraviolet Research Telescop...
متن کاملX-ray emission lines from inhomogeneous stellar winds
It is commonly adopted that X-rays from O stars are produced deep inside the stellar wind, and transported outwards through the bulk of the expanding matter which attenuates the radiation and affects the shape of emission line profiles. The ability of the X-ray observatories Chandra and XMM-Newton to resolve these lines spectroscopically provided a stringent test for the theory of the X-ray pro...
متن کاملEmission Lines in X-ray Spectra of Clusters of Galaxies
Emission lines in X–ray spectra of clusters of galaxies reveal the presence of heavy elements in the diffuse hot plasma (the Intra Cluster Medium, or ICM) in virial equilibrium in the dark matter potential well. The relatively simple physical state of the ICM allows us to estimate, with good accuracy, its thermodynamical properties and chemical abundances. These measures put strong constraints ...
متن کاملHelium shells and faint emission lines from slitless flash spectra
At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the neutral helium HeI line at 4713 Å. The extensions...
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 1948
ISSN: 0004-6256
DOI: 10.1086/106062