Journal Article

On the importance of satellite lines to the helium-like Kα complex and the <i>G</i> ratio for calcium, iron and nickel

J. Oelgoetz, C. J. Fontes, H. L. Zhang, S. N. Nahar and A. K. Pradhan

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 2, pages 742-750
Published in print April 2009 | ISSN: 0035-8711
Published online March 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14248.x
On the importance of satellite lines to the helium-like Kα complex and the G ratio for calcium, iron and nickel

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New, more detailed calculations of the emission spectra of the He-like Kα complex of calcium, iron and nickel have been carried out using data from both distorted-wave and R-matrix calculations. The value of the GD ratio (an extended definition of the G ratio that accounts for the effect of resolved and unresolved satellite lines) is significantly enhanced at temperatures below the temperature of He-like maximum abundance. Furthermore, it is shown that satellite lines are important contributors to the GD ratio such that GD/G > 1 at temperatures well above the temperature of maximum abundance. These new calculations demonstrate, with an improved treatment of the KLn satellite lines, that Kα satellite lines need to be included in models of He-like spectra even at relatively high temperatures. The excellent agreement between spectra and line ratios calculated from R-matrix and distorted-wave data also confirms the validity of models based on distorted-wave data for highly charged systems, provided the effect of resonances is taken into account as independent processes.

Keywords: atomic data; atomic processes; line: formation; line: profiles; X-rays: general

Journal Article.  5428 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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