EUV Spectroscopy of Hot DA White Dwarfs

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Session 47 -- Degenerates
Display presentation, Wednesday, 9:20-6:30, Pauley Room

[47.02] EUV Spectroscopy of Hot DA White Dwarfs

David S. Finley (Eureka Scientific, Inc.), Detlev Koester (Louisiana State University), Gerard Vauclair (University Paul Sabatier, Observatoire Midi-Pyrenees, Laboratoire d'Astrophysique de Toulouse)

The effects of trace elements on the spectra of hot DA white dwarfs are most pronounced in the extreme ultraviolet (EUV), shortward of 300~\AA~. We have obtained EUV spectra of several DA which were observed with the Extreme Ultraviolet Explorer spectrometer, which has a resolution of $\lambda / \delta \lambda~=~300~-~400$, and covers the wavelength range 70 -- 760~\AA~. We have analyzed these spectra using models which self-consistently include the opacities of trace heavy elements. We confirm the photometric result that a wide range of trace element abundances exists among the hot DA. We further find that, contrary to expectations, large abundance differences can exist even between DA which have very similar effective temperatures and gravities, as is the case for G191-B2B and GD 246.

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