AAS 200th meeting, Albuquerque, NM, June 2002
Session 72. Degenerates
Display, Thursday, June 6, 2002, 9:20am-4:00pm, SW Exhibit Hall

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[72.05] A High S/N View of the Photosphere of the Hot White Dwarf G191-B2B from STIS

J. B. Holberg (Lunar and Planetary Lab., University of Arizona), M. A. Barstow (University of Leicester), I Hubeny (National Optical Astronomy Observatories), M. S. Sahu, F. C. Bruhweiler (NASA/GSFC & Catholic University of America), W. B. Landsman (SSAI & NASA/GSFC)

We have assembled a unique, high signal-to-noise (S/N) spectrum of the hot metal-rich DA white dwarf, G191-B2B, from a coaddition of 22 E140H and 40 E230H STIS calibration spectra. This superb data set fully covers the wavelength range from 1155 A to 3169 A with S/N ranging from over 100 to 30; affording an unprecedentedly detailed view of the UV stellar absorption lines in a white dwarf star. We use this spectrum to search for a number of previously undiscovered heavy elements in the G191-B2B photosphere and to estimate elemental abundances and place upper limits on the abundances of a number of key species. An accurate photospheric inventory of heavy elements in hot degenerate stars is basic to our understanding of the chemical diffusion in these stars. These observations highlight the wealth of information present in echelle resolution spectra of white dwarfs such as G191-B2B and the need for a succeeding generation of UV instrumentation capable of providing data of this type for other degenerate stars. This work funded by STScI Grant AR 9202.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.