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Astron. Astrophys. 341, 795-798 (1999)


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[FORMULA] Hya: spectroscopic identification of a second B star+white dwarf binary

M.R. Burleigh and M.A. Barstow

Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK

Received 14 September 1998 / Accepted 9 October 1998

Abstract

We report the identification, in an Extreme Ultraviolet Explorer (EUVE) spectrum, of a hot white dwarf companion to the 3rd magnitude late-B star [FORMULA] Hya (HR3665, HD79469). This is the second B star+white dwarf binary to be conclusively identified; Vennes et al. (1997), and Burleigh & Barstow (1998) had previously reported the spectroscopic discovery of a hot white dwarf companion to the B5V star y Pup (HR2875). Since these two degenerate stars must have evolved from main sequence progenitors more massive than their B star companions, they can be used to place observational lower limits on the maximum mass for white dwarf progenitors, and to investigate the upper end of the initial-final mass relation. Assuming a pure hydrogen composition, we constrain the temperature of the white dwarf companion to [FORMULA] Hya to lie between 25,000K and 31,000K. We also predict that a third bright B star, 16 Dra (B9.5V), might also be hiding an unresolved hot white dwarf companion.

Key words: stars: white dwarfs – stars: binaries: general – stars: individual: Hya

Send offprint requests to: Matt Burleigh (mbu@star.le.ac.uk)

© European Southern Observatory (ESO) 1999

Online publication: December 16, 1998

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