Is there a planet in the PSR 1620-26 triple system?

Frederic A. Rasio*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


The unusually large eccentricity (e1 = 0.025) of the low-mass binary millisecond pulsar PSR B1620-26 can be explained naturally as arising from the secular perturbation of a second, more distant companion. Such a triple configuration has been proposed recently as the most likely cause of the anomalous second period derivative of the pulsar. The current timing data are consistent with a second-companion mass m2 as low as ∼10-3 M, i.e., comparable to that of Jupiter. However, if the eccentricity is indeed produced by secular perturbations, then the second companion must be another star, most likely of mass m2 ≤ 1 M and in a very eccentric (e2 ≥ 0.5) orbit of period P2 ∼ 102-103 yr. A second companion of planetary mass cannot induce the observed eccentricity. Independent of the mass of the second companion, small changes in the binary pulsar's orbit should become detectable with just a few additional years of timing data. This detection would provide direct confirmation of the triple nature of the system, and an accurate measurement of the effects would place important new constraints on the orbital parameters.

Original languageEnglish (US)
Pages (from-to)L107-L110
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Jun 1 1994


  • Binaries: close
  • Celestial mechanics, stellar dynamics
  • Planetary systems
  • Pulsars: general
  • Pulsars: individual (PSR B1620-26)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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