Double-degenerate semidetached binaries with helium secondaries: cataclysmic variables, supersoft X-ray sources, supernovae and accretion-induced collapses
Abstract
We model the galactic population of ultrashort-period binaries with helium white dwarf (WD) donors and carbon-oxygen WD accretors. Their total number is ~10^8. Our model suggests that ~10 systems of this kind, with <e1>V<=</e1>13.0 mag, 6<~P_orb<~50 min and 0.03<~M_2/M_<~0.15, may be observed. The rate of accretion-induced collapses in all systems with helium donors is a strong function of the efficiency of the orbital energy dissipation in the common envelope stages preceding their formation, and may be as high as ~10^-5 yr^-1. The total galactic rate of supernova-scale events induced by helium shell flashes on accreting white dwarfs in binary systems with degenerate and non-degenerate helium donors may be as high as ~5x10^-3 yr^-1, comparable to the estimates of the galactic rate of type Ia supernovae. We estimate that among semidetached double-degenerate systems with helium donors up to ~100 may be luminous supersoft X-ray sources which arise as a result of stationary helium burning at the surface of an accreting dwarf and/or of the presence of compact hot discs. Typical orbital periods of these systems are ~2-4 min.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- June 1996
- DOI:
- 10.1093/mnras/280.4.1035
- Bibcode:
- 1996MNRAS.280.1035T
- Keywords:
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- ACCRETION;
- ACCRETION DISCS;
- BINARIES: CLOSE;
- NOVAE;
- CATACLYSMIC VARIABLES;
- SUPERNOVAE: GENERAL;
- X-RAYS: GENERAL