Violent stellar merger model for transient events |
| |
| Authors: | Noam Soker Romuald Tylenda |
| |
| Institution: | Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel;Department for Astrophysics, N.Copernicus Astronomical Centre, Rabiańska 8, 87-100 Toruń, Poland |
| |
| 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 ? ( M 2/ M 1) ? 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 ～106 L⊙ followed by a slow decline at very low effective temperatures. |
| |
| Keywords: | stars: individual: V838 Mon stars: individual: V4332 Sgr stars: individual: M31 RV stars: mass-loss stars: pre-main-sequence supergiants |
|
|
