The dynamical significance of triple star systems in star clusters

Nathan W.C. Leigh*, Aaron M. Geller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Over the last few decades, observational surveys have revealed that high-order multiple-star systems (e.g. triples, quadruples, etc.), and triples in particular, are common in our Galaxy. In this paper, we consider the dynamical significance of this transformation in our understanding of stellar multiplicity. Using empirically constrained binary and triple fractions in those star clusters for which these values are available in the literature, we compare analytic rates for encounters involving single, binary and triple stars. Our results show that, even for relatively low triple fractions, dynamical interactions involving triples occur roughly as often as, or even more often than, encounters involving either single or binary stars alone, particularly in low-mass star clusters. More generally, using empirically derived multiple star catalogues for the young star-forming association Taurus-Auriga and the Galactic field, we show that the data are consistent with the gravitationally focused cross-section for encounters increasing with increasing multiplicity. Consequently, triple stars, and even higher order multiples, could be more important than previously realized for a number of astrophysical phenomena, including the formation and destruction of compact binaries and various types of stellar exotica and the dynamical evolution of star clusters.

Original languageEnglish (US)
Pages (from-to)2474-2479
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Jun 2013


  • Binaries: close
  • Globular clusters: general
  • Gravitation
  • Open clusters and associations: general
  • Stars: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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