A possible spin-orbit misalignment in the transiting eccentric planet HD 17156b

Norio Narita, Bun'ei Sato, Osamu Ohshima, Joshua N. Winn

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46 Scopus citations


We present simultaneous photometric and spectroscopic observations of HD 17156b spanning a transit on 2007 November 12 (UT). This system is of special interest because of its 21 d period (unusually long for a transiting planet) and its high orbital eccentricity of 0.67. By modeling the Rossiter-McLaughlin effect, we find the angle between the sky projections of the orbital axis and the stellar rotation axis to be 62°±25°. Such a large spin-orbit misalignment, as well as the high eccentricity, could be explained as a relic of a previous gravitational interaction with other planets.

Original languageEnglish (US)
Pages (from-to)L1-L5
JournalPublications of the Astronomical Society of Japan
Issue number2
StatePublished - 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Stars: planetary systems: individual (HD 17156)
  • Stars: rotation
  • Techniques: photometric
  • Techniques: radial velocities
  • Techniques: spectroscopic


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