Violent stellar merger model for transient events
Abstract
We derive the constraints on the mass ratio for a binary system to merge in a violent process. We find that the secondary-to-primary stellar mass ratio should be 0.003 <~ (M2/M1) <~ 0.15. A more massive secondary star will keep the primary stellar envelope in synchronized rotation with the orbital motion until merger occurs. This implies a very small relative velocity between the secondary star and the primary stellar envelope at the moment of merger, and therefore very weak shock waves, and low-flash luminosity. A too low-mass secondary will release small amount of energy, and will expel small amount of mass, which is unable to form an inflated envelope. It can, however, produce a quite luminous but short flash when colliding with a low-mass main-sequence star.
Violent and luminous mergers, which we term mergebursts, can be observed as V838 Monocerotis-type events, where a star undergoes a fast brightening lasting days to months, with a peak luminosity of up to ~106Lsolar followed by a slow decline at very low effective temperatures.- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2006
- DOI:
- 10.1111/j.1365-2966.2006.11056.x
- arXiv:
- arXiv:astro-ph/0606467
- Bibcode:
- 2006MNRAS.373..733S
- Keywords:
-
- stars: individual: V838 Mon;
- stars: individual: V4332 Sgr;
- stars: individual: M31 RV;
- stars: mass-loss;
- stars: pre-main-sequence;
- supergiants;
- Astrophysics
- E-Print:
- Accepted by MNRAS