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The close DAO+dM binary RE J0720-318: a stratified white dwarf with a thin H layer and a possible circumbinary disk

Citation

Burleigh, MR and Barstow, MA and Dobbie, PD, The close DAO+dM binary RE J0720-318: a stratified white dwarf with a thin H layer and a possible circumbinary disk, Astronomy & Astrophysics, 317, (1) pp. L27-L30. ISSN 0004-6361 (1997) [Refereed Article]


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Copyright Statement

Copyright 1997 Astronomy and Astrophysics

Official URL: http://aa.springer.de/tocs/t7317001.htm

Abstract

We have analysed the EUVE spectrum of the DAO white dwarf RE J0720-318. In contrast to the optical spectrum, which can only be fitted with a homogeneously mixed H+He atmosphere, we find the EUVE spectrum can only be matched with a stratified structure. The H layer mass of 3x10-14 M⊙, is a factor of ~10 below upper limits from previous EUVE observations of white dwarfs. In addition, we detect an unprecedented HeI/HI ratio of ~1 for the absorbing column along the line of sight, implying an H ionization fraction >90% if all this material resides in the local ISM. We suggest that, since this is a close pre-CV binary system, most of the helium probably lies within the immediate vicinity of the star, possibly in the form of a circumbinary disk left over from the common envelope (CE) phase. These results have important implications for our understanding of the evolutionary status of DAO white dwarfs in particular, and for post-CE binaries in general.

Item Details

Item Type:Refereed Article
Keywords:binaries, close stars, RE J0720-318 stars, abundances, star evolution, white dwarfs
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Stellar Astronomy and Planetary Systems
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Dobbie, PD (Dr Paul Dobbie)
ID Code:81198
Year Published:1997
Web of Science® Times Cited:6
Deposited By:Mathematics and Physics
Deposited On:2012-11-26
Last Modified:2013-06-25
Downloads:0

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