Collisions and close encounters involving massive main-sequence stars
Författare
Summary, in English
We study close encounters involving massive main-sequence stars and the evolution of the exotic products of these encounters as common-envelope systems or possible hypernova progenitors. We show that parabolic encounters between low- and high-mass stars and between two high-mass stars with small periastrons result in mergers on time-scales of a few tens of stellar free-fall times (a few tens of hours). We show that such mergers of unevolved low-mass stars with evolved high-mass stars result in little mass-loss (similar to 0.01 M-circle dot) and can deliver sufficient fresh hydrogen to the core of the collision product to allow the collision product to burn for several million years. We find that grazing encounters enter a common-envelope phase which may expel the envelope of the merger product. The deposition of energy in the envelopes of our merger products causes them to swell by factors of similar to 100. If these remnants exist in very densely populated environments (n greater than or similar to 10(7) pc(-3)), they will suffer further collisions which may drive off their envelopes, leaving behind hard binaries. We show that the products of collisions have cores rotating sufficiently rapidly to make them candidate hypernova/gamma-ray burst progenitors and that similar to 0.1 per cent of massive stars may suffer collisions, sufficient for such events to contribute significantly to the observed rates of hypernovae and gamma-ray bursts.
Avdelning/ar
Publiceringsår
2006
Språk
Engelska
Sidor
1424-1436
Publikation/Tidskrift/Serie
Monthly Notices of the Royal Astronomical Society
Volym
366
Issue
4
Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Oxford University Press
Ämne
- Astronomy, Astrophysics and Cosmology
Nyckelord
- gamma-rays : bursts
- blue stragglers
- supernovae : general
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 1365-2966