Measurement of the spin-orbit alignment in the exoplanetary system HD 189733

Joshua N. Winn, John Asher Johnson, Geoffrey W. Marcy, R. Paul Butler, Steven S. Vogt, Gregory W. Henry, Anna Roussanova, Matthew J. Holman, Keigo Enya, Norio Narita, Yasushi Suto, Edwin L. Turner

Research output: Contribution to journalArticlepeer-review

108 Scopus citations


We present spectroscopy of a transit of the exoplanet HD 189733b. By modeling the Rossiter-McLaughlin effect (the anomalous Doppler shift due to the partial eclipse of the rotating stellar surface), we find the angle between the sky projections of the stellar spin axis and orbit normal to be λ = -1°4 ±1°.1. This is the third case of a "hot Jupiter" for which λ has been measured. In all three cases λ is small, ruling out random orientations with 99.96% confidence, and suggesting that the inward migration of hot Jupiters generally preserves spin-orbit alignment.

Original languageEnglish (US)
Pages (from-to)L69-L72
JournalAstrophysical Journal
Issue number1 II
StatePublished - Dec 10 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Planetary systems: formation
  • Stars: individual (HD 189733)
  • Stars: rotation


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