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A. M. Juett, N. S. Schulz, D. Chakrabarty, C. R. Canizares (MIT)
We have used photoelectric absorption features in the Chandra/HETGS spectra of eight bright X-ray binaries to study the relative abundances of O, Fe, and Ne in the interstellar medium (ISM). We find Ne/O abundance ratios up to twice as large as predicted by standard ISM models, and Fe/O ratios of 0.6--1 times the predicted ratio. The shape and wavelength of the photoelectric edges is used to discriminate between atomic and molecular forms of these elements. We found that the O edge contains complex structure and measured edge wavelengths range from the expected atomic value of 22.78~Å\/ up to 23.3~Å, presumably due to molecular effects. Through these measurements, we hope to better understand the line of sight variations in the abundances and to produce a universal absorption edge model for use by the community.
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.