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How much hydrogen is there in a white dwarf?Stratified hydrogen/helium envelope models in diffusive equilibrium are calculated for a 0.6-solar-mass white dwarf for effective temperatures between 10,000 and 80,000 K in order to investigate the observational constraints placed on the total hydrogen mass. Convective mixing is included ab initio in the calculations, and synthetic spectra are used for comparing these models with observational materials. It is shown that evolutionary changes in the surface composition of white dwarfs cannot be explained by a model in which a small amount of hydrogen floats to the surface from initially being mixed in the outer parts of a helium envelope. It is pointed out that the shape of the hydrogen lines can be used for constraining theories of convective overshoot.
Document ID
19910048956
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Macdonald, James
(Delaware Univ. Newark, DE, United States)
Vennes, Stephane
(Delaware, University Newark, United States)
Date Acquired
August 14, 2013
Publication Date
April 20, 1991
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 371
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
91A33579
Funding Number(s)
CONTRACT_GRANT: NAG5-972
CONTRACT_GRANT: NSF AST-87-20530
Distribution Limits
Public
Copyright
Other

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