The triple evolution dynamical instability: Stellar collisions in the field and the formation of exotic binaries

Hagai B. Perets, Kaitlin M. Kratter

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

Physical collisions and close approaches between stars play an important role in the formation of exotic stellar systems. Standard theories suggest that collisions are rare, occurring only via random encounters between stars in dense clusters. We present a different formation pathway, the triple evolution dynamical instability (TEDI), in which mass loss in an evolving triple star system causes orbital instability. The subsequent chaotic orbital evolution of the stars triggers close encounters, collisions, exchanges between the stellar components, and the dynamical formation of eccentric compact binaries (including Sirius-like binaries). We demonstrate that the rate of stellar collisions due to the TEDI is approximately 10-4 yr-1 per Milky Way Galaxy, which is nearly 30 times higher than the total collision rate due to random encounters in the Galactic globular clusters. Moreover, we find that the dominant type of stellar collision is qualitatively different; most collisions involve asymptotic giant branch stars, rather than main sequence or slightly evolved stars, which dominate collisions in globular clusters. The TEDI mechanism should lead us to revise our understanding of collisions and the formation of compact, eccentric binaries in the field.

Original languageEnglish (US)
Article number99
JournalAstrophysical Journal
Volume760
Issue number2
DOIs
StatePublished - Dec 1 2012
Externally publishedYes

Keywords

  • binaries: close
  • binaries: general
  • instabilities
  • stars: AGB and post-AGB
  • stars: evolution
  • stars: kinematics and dynamics
  • stars: mass-loss
  • white dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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