Improved Measurement of the Rossiter-McLaughlin Effect in the Exoplanetary System HD 17156

• Main Authors: Winn, Joshua Nathan (Contributor), Narita, Norio (Author), Hirano, Teruyuki (Author), Sato, Bunei (Author), Suto, Yasushi (Author), Turner, Edwin L. (Author), Aoki, Wako (Author), Tamura, Motohide (Author), Yamada, Toru (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), MIT Kavli Institute for Astrophysics and Space Research (Contributor)
• Format: Article
• Language: English
• Published: Astronomical Society of Japan, 2013-02-06T15:38:18Z.
• Subjects: Article
• Online Access: Get fulltext

 We present an improved measurement of the Rossiter-McLaughlin effect for the exoplanetary system HD 17156, based on radial-velocity data gathered with the Subaru 8.2m telescope throughout the planetary transit of UT 2008 November 7. The data allow for a precise and independent determination of the projected spin-orbit angle of this system: λ = 10[° over .]0 ± 5[° over .]1. This result supersedes the previous claim of λ = 62° ± 25° by Narita et al., which was based on lower-precision data with poor statistics. Thus the stellar spin and planetary orbital axes of the HD 17156 system are likely to be well-aligned, despite the planet's large orbital eccentricity suggesting a history of strong dynamical interactions.