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J.J. Drake, V. Kashyap (Smithsonian Astrophysical Observatory), J.M. Laming, L. Lin (Naval Research Laboratory)
Much of modern astrophysics is grounded on the observed chemical compositions of stars and the diffuse plasma that pervades the space between stars, galaxies and clusters of galaxies. X-ray and EUV spectra of the hot plasma in the outer atmospheres of stars have demonstrated that these environments are subject to chemical fractionation in which the abundances of elements can be enhanced and depleted by an order of magnitude or more. We present new plasma diagnostics for measuring abundances ratios in hot optically-thin plasma based on high resolution X-ray spectra. These diagnostics are insensitive to temperature and can be applied to sources for which the detailed knowledge of the plasma thermal characteristics is uncertain. We apply these diagnostics to high resolution Chandra X-ray spectra of active stars and discuss the results in the context of the processes and environments in which hot astrophysical plasmas can become chemically fractionated.
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.