Violent stellar merger model for transient events

Noam Soker*, Romuald Tylenda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

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 ∼10 6L followed by a slow decline at very low effective temperatures.

Original languageEnglish
Pages (from-to)733-738
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Volume373
Issue number2
DOIs
StatePublished - Dec 2006
Externally publishedYes

Keywords

  • Stars: individual: M31 RV
  • Stars: individual: V4332 Sgr
  • Stars: individual: V838 Mon
  • Stars: mass-loss
  • Stars: pre-main-sequence
  • Supergiants

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