Hya: spectroscopic identification of a second B star+white dwarf binary
M.R. Burleigh and
Received 14 September 1998 / Accepted 9 October 1998
We report the identification, in an Extreme Ultraviolet Explorer (EUVE) spectrum, of a hot white dwarf companion to the 3rd magnitude late-B star 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 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
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© European Southern Observatory (ESO) 1999
Online publication: December 16, 1998