Spin-orbit alignment for the eccentric exoplanet HD 147506b

Joshua N. Winn, John Asher Johnson, Kathryn M.G. Peek, Geoffrey W. Marcy, Gaspar A. Bakos, Keigo Enya, Norio Narita, Yasushi Suto, Edwin L. Turner, Steven S. Vogt

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


The short-period exoplanet HD 147506b (also known as HAT-P-2b) has an eccentric orbit, raising the possibility that it migrated through planet-planet scattering or Kozai oscillations accompanied by tidal dissipation. Either of these scenarios could have significantly tilted the orbit relative to the host star's equatorial plane. Here we present spectroscopy of a transit of HD 147506b and assess the spin-orbit alignment via the Rossiter-McLaughlin effect. We find the angle between the sky projections of the stellar spin axis and orbital axis to be aligned within 14°. Thus, we find no corroborating evidence for scattering or Kozai migration, although these scenarios cannot be ruled out with the present data.

Original languageEnglish (US)
Pages (from-to)L167-L170
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Planetary systems: formation
  • Stars: individual (HD 147506, HAT-P-2)
  • Stars: rotation


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