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 (n ≥ 3) 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.


Relevant data is available at: http://www.astronomy.ohio-state.edu/~nahar/nahar_radiativeatomicdata/index.html
The definitive version is available at www.blackwell-synergy.com. http://www3.interscience.wiley.com/journal/122240142/abstract


atomic data, atomic processes, line -- formation, line -- profiles, X-rays -- general


Oelgoetz, J., Fontes, C. J., Zhang, H. L., Nahar, Sultana Nurun, Pradhan, A. K. "On the importance of satellite lines to the helium-like Kα complex and the G ratio for calcium, iron and nickel," Monthly Notices of the Royal Astronomical Society, v. 394, no. 2, 2009, pp. 742-750.