Apsidal behavior among planetary orbits: Testing the planet-planet scattering model

Rory Barnes, Richard Greenberg

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Planets in extrasolar systems tend to interact such that their orbits lie near a boundary between apsidal libration and circulation, a "separatrix," with one eccentricity periodically reaching near zero. One explanation, applied to the v And system, assumed three original planets on circular orbits. One is ejected, leaving the other two with near-separatrix behavior. We test that model by integrating hundreds of hypothetical, unstable planetary systems that eject a planet. We find that the probability that the remaining planets exhibit near-separatrix motion is small (<5% compared with nearly 50% of observed systems). Moreover, while observed librating systems are evenly divided between aligned and antialigned pericenter longitudes, the scattering model strongly favors alignment. Alternative scattering theories are proposed, which may provide a more satisfactory fit with observed systems.

Original languageEnglish (US)
Pages (from-to)L53-L56
JournalAstrophysical Journal
Issue number1 II
StatePublished - Apr 10 2007


  • Methods: n-body simulations
  • Planetary systems
  • Planets and satellites: formation

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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