Theta Hya: spectroscopic identification of a second B star+white dwarf binary
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 theta 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 theta 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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1999
- DOI:
- 10.48550/arXiv.astro-ph/9810113
- arXiv:
- arXiv:astro-ph/9810113
- Bibcode:
- 1999A&A...341..795B
- Keywords:
-
- STARS: WHITE DWARFS;
- STARS: BINARIES: GENERAL;
- STARS: INDIVIDUAL: THETA HYA;
- Astrophysics
- E-Print:
- 4 pages, 1 figure. Accepted for publication in Astronomy and Astrophysics