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Astron. Astrophys. 324, 410-416 (1997)

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Effect of iron ionization balance on X-ray spectral analysis

K. Masai

Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-03, Japan

Received 14 October 1996 / Accepted 29 January 1997


We have investigated the uncertainty in the ionization and recombination rates for iron and its impact on the derivation of the iron elemental abundance from X-ray emission spectra. Most uncertainty is found in the dielectronic recombination rates for iron ions with L-shell outer electrons. The quantitative effect of this uncertainty on the derivation of the iron abundance depends on the spectral resolving power of X-ray detectors. With the resolution achieved by ASCA, the differences among ionization balance models come out to [FORMULA] 30% in the iron elemental abundance and [FORMULA] 15% in the temperature at temperatures [FORMULA] 1 keV. To eliminate the effects of the ionization balance, finally, we suggest taking ionization temperature as well as the electron temperature into account for spectral analysis. This way is useful also for plasmas in the presence of ionizing photons.

Key words: atomic and molecular processes – plasmas – X-rays: general


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© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998