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The constitution of the atmospheric layers and the extreme ultraviolet spectrum of hot hydrogen-rich white dwarfsAn analysis is presented of the atmospheric properties of hot, H-rich, DA white dwarfs that is based on optical, UV, and X-ray observations aimed at predicting detailed spectral properties of these stars in the range 80-800 A. The divergences between observations from a sample of 15 hot DA white dwarfs emitting in the EUV/soft X-ray range and pure H synthetic spectra calculated from a grid of model atmospheres characterized by Teff and g are examined. Seven out of 15 DA stars are found to consistently exhibit pure hydrogen atmospheres, the remaining seven stars showing inconsistency between FUV and EUV/soft X-ray data that can be explained by the presence of trace EUV/soft X-ray absorbers. Synthetic data are computed assuming two other possible chemical structures: photospheric traces of radiatively levitated heavy elements and a stratified hydrogen/helium distribution. Predictions about forthcoming medium-resolution observations of the EUV spectrum of selected hot H-rich white dwarfs are made.
Document ID
19920054155
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Vennes, Stephane
(Delaware, University Newark; California, University, Berkeley, United States)
Date Acquired
August 15, 2013
Publication Date
May 10, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 390
Issue: 2 Ma
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
92A36779
Funding Number(s)
CONTRACT_GRANT: NSF AST-87-20530
CONTRACT_GRANT: NAG5-972
CONTRACT_GRANT: NAS5-30180
Distribution Limits
Public
Copyright
Other

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