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The distribution of metals in hot DA white dwarfs

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journal contribution
posted on 2014-04-24, 10:53 authored by Nathan J. Dickinson, Martin A. Barstow, I. Hubeny
The importance to stellar evolution of understanding the metal abundances in hot white dwarfs is well known. Previous work has found the hot DA white dwarfs REJ 1032+532, REJ 1614-085 and GD 659 to have highly abundant, stratified photospheric nitrogen, due to the narrow absorption-line profiles of the far-ultraviolet (FUV) Nv doublet and the lack of extreme-ultraviolet (EUV) continuum absorption. A preliminary analysis of the extremely narrow, deep line profiles of the photospheric metal absorption features of PG 0948+534 suggested a similar photospheric metal configuration. However, other studies have found that REJ 1032+532, REJ 1614-085 and GD 659 can be well described by homogeneous models, with nitrogen abundances more in keeping with those of white dwarfs with higher effective temperatures. Here, a re-analysis of the nitrogen absorption features seen in REJ 1032+532, REJ 1614-085 and GD 659 is presented, with the aim of better understanding the structure of these stars, to test which models better represent the observed data and apply the results to the line profiles seen in PG 0948+534. A degeneracy is seen in the modelling of the nitrogen absorption-line profiles of REJ 1032+532, REJ 1614-085 and GD 659, with low-abundance, homogeneously distributed nitrogen models most likely being a better representation of the observed data. In PG 0948+534, no such degeneracy is seen, and the enigmatically deep line profiles could not be modelled satisfactorily.

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STFC

History

Citation

Monthly Notices of the Royal Astronomical Society, 2012, 421 (4), pp. 3222-3228

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press

issn

0035-8711

eissn

1365-2966

Copyright date

2012

Available date

2014-04-24

Publisher version

http://mnras.oxfordjournals.org/content/421/4/3222

Language

en

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