Ion storage ring measurements of dielectronic recombination for astrophysically relevant Fe[sup q+] ions
- Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany)
Iron ions provide many valuable plasma diagnostics for cosmic plasmas. The accuracy of these diagnostics, however, often depends on an accurate understanding of the ionization structure of the emitting gas. Dielectronic recombination (DR) is the dominant electron-ion recombination mechanism for most iron ions in cosmic plasmas. Using the heavy-ion storage ring at the Max-Planck-Institute for Nuclear Physics in Heidelberg, Germany, we have measured the low temperature DR rates for Fe[sup q+] where q=15, 17, 18, and 19. These rates are important for photoionized gases which form in the media surrounding active galactic nuclei, X-ray binaries, and cataclysmic variables. Our results demonstrate that commonly used theoretical approximations for calculating low temperature DR rates can easily under- or over-estimate the DR rate by a factor of [approximately]2 or more. As essentially all DR rates used for modeling photoionized gases are calculated using these approximations, our results indicate that new DR rates are needed for almost all charge states of cosmically abundant elements. Measurements are underway for other charge states of iron. [copyright] [ital 1999 American Institute of Physics.]
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5903199
- Report Number(s):
- CONF-981122-; CODEN: APCPCS
- Journal Information:
- AIP Conference Proceedings, Vol. 475:1; Conference: 15. international conference on the application of accelerators in research and industry, Denton, TX (United States), 4-7 Nov 1998; ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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