The orbital eccentricities of binary millisecond pulsars in globular clusters

Frederic A. Rasio*, Douglas C. Heggie

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


Low-mass binary millisecond pulsars (LMBPs) are born with very small orbital eccentricities, typically of order ei ∼ 10-6-10-3. In globular clusters, however, higher eccentricities ef ≫ ei can be induced by dynamical interactions with passing stars. Here we show that the cross section for this process is much larger than previously estimated. This is because, even for initially circular binaries, the induced eccentricity ef for an encounter with percenter separation rp beyond a few times the binary semimajor axis a declines only as a power law, ef ∝ (rp/a)-5/2, and not as an exponential. We find that all currently known LMBPs in clusters were probably affected by interactions, with their current eccentricities typically greater than at birth by an order of magnitude or more.

Original languageEnglish (US)
Pages (from-to)L133-L135
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Jun 1 1995


  • Binaries: close
  • Celestial mechanics, stellar dynamics
  • Globular clusters: general
  • Pulsars: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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