Journal Article10.1086/344745
Indirect X-Ray Line-Formation Processes in Iron L-Shell Ions
TL;DR: In this paper, the role of indirect processes in the soft X-ray line formation of iron L-shell ions, using a newly developed, relativistic, multiconfigurational atomic package, was investigated.
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Abstract: We present a systematic study of the role of indirect processes in the soft X-ray line formation of iron L-shell ions, using a newly developed, relativistic, multiconfigurational atomic package. These indirect processes involve the neighboring charge states of the target ion, namely, radiative recombination, dielectronic recombination, and resonance excitation. For Fe XVII, the inner-shell collisional ionization (CI) is also relevant. Lines originating from 3s and 3p upper levels of Fe XVII-XX are found to be significantly affected by these processes, with some lines being enhanced by nearly a factor of 2 at the temperature of maximum fractional abundance in CI equilibrium. Such enhancement, although not enough to completely explain the observed line ratios from various astrophysical sources, is a vast improvement over the previous models neglecting these processes. Rate coefficients for individual processes are tabulated, which can be conveniently included in spectral models to correctly account for these effects. As a by-product of this investigation, the total recombination and ionization rates of all Fe L-shell ions are tabulated as a function of temperature.
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Yong-Ki Kim,M. Eugene Rudd +1 more
TL;DR: In this article, a theoretical model for calculating electron-impact ionization cross sections for atoms and molecules is presented, which combines the binary-encounter theory with the dipole interaction of the Bethe theory for fast incident electrons.
Iron ionization and recombination rates and ionization equilibrium
M. Arnaud,J. Raymond +1 more
TL;DR: In this article, a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(−25) using the photoionization cross sections of Clark et al.
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High-Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High-Energy Transmission Grating Spectrometer
Claude R. Canizares,David P. Huenemoerder,David S. Davis,Daniel Dewey,Kathryn A. Flanagan,John C. Houck,Thomas H. Markert,Herman L. Marshall,Mark L. Schattenburg,Norbert S. Schulz,Michael W. Wise,Jeremy J. Drake,Nancy Brickhouse +12 more
TL;DR: In this article, high-resolution spectra of the active binary Capella (G8 III + G1 III) covering the energy range of 0.4-8.0 keV (1.5-30 A) show a large number of emission lines, demonstrating the performance of the High Energy Transmission Grating Spectrometer.
Laboratory Measurements and Modeling of the Fe XVII X-Ray Spectrum
Gregory V. Brown,Gregory V. Brown,Peter Beiersdorfer,Duane A. Liedahl,Klaus Widmann,Steven M. Kahn +5 more
TL;DR: In this article, the Fe XVII L-shell emission spectrum between 9.8 and 17.5 A was analyzed under precisely controlled conditions where electron-impact excitation followed by radiative cascades is the dominant line formation process.
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