On the importance of satellite lines to the He-like K ALPHA complex and the G ratio for calcium, iron, and nickel

Abstract

New, more detailed calculations of the emission spectra of the He-like K ALPHA 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 (n>=3) satellite lines, that K ALPHA 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 are taken into account as independent processes.

12 pages, 5 figures, to appear in Monthly Notices of the Royal Astronomical Society. The definitive version is available at www.blackwell-synergy.com

References in corpus (3)

• Chandra High Resolution X-ray Spectroscopy of AM Her
• A study of the breakdown of the quasi-static approximation at high densities and its effect on the helium-like K ALPHA complex of nickel, iron, and calcium
• High-temperature behaviour of the helium-like K ALPHA G ratio: the effect of improved recombination rate coefficients for calcium, iron, and nickel