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The Metallicity of Hot DA White Dwarfs as Inferred from EUV Photometry

Published online by Cambridge University Press:  12 April 2016

David S. Finley
David S. Finley*
Affiliation:
Center for EUV Astrophysics, University of California, 2150 Kittredge Street, Berkeley, CA94720-5030

Abstract

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Photometric EUV observations have shown that the hotter DA white dwarfs tend to show significant excess opacity relative to hydrogen. EUV and high-resolution FUV spectroscopy have conclusively demonstrated that the excess opacity is due to the presence of trace heavy elements in the white dwarf photospheres. In the past, the general abundance distribution in hot DA has been studied as a function of temperature, assuming that He was the trace absorber. We present here the first determination of the variation of relative total heavy element abundances in DA as a function of both temperature and gravity using realistic models that include metals. We compare the observational results with theoretical calculations of equilibrium abundances due to radiative acceleration.

Type
IV. White Dwarf Structure/Evolution
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 223 - 228
Copyright
Copyright © Kluwer 1996

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