2008/06/04 by G. Hebrard, G. Hébrard, F. Bouchy +23 · 220 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Exoplanet #Observatory #Orbital plane #Planet #Planetary migration #Planetary system #Radial velocity #Spectrograph #Stellar rotation #Stellar, planetary, and galactic studies #Transit (satellite) #astro-ph
paper · pdf · doi:10.1051/0004-6361:200810056
published in Astronomy and Astrophysics 488(2), 763-770 (EDP Sciences) · 8 pages, 8 figures, 3 tables, to be published in A&A
arxiv created 2008/06/04 · openalex publication_date 2008/07/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The transiting extrasolar planet XO-3b is remarkable, with a high mass and eccentric orbit. These unusual characteristics make it interesting to test whether its orbital plane is parallel to the equator of its host star, as it is observed for other transiting planets. We performed radial velocity measurements of XO-3 with the SOPHIE spectrograph at the 1.93 m telescope of Haute-Provence Observatory during a planetary transit and at other orbital phases. This allowed us to observe the Rossiter-McLaughlin effect and, together with a new analysis of the transit light curve, to refine the parameters of the planet. The unusual shape of the radial velocity anomaly during the transit provides a hint of a nearly transverse Rossiter-McLaughlin effect. The sky-projected angle between the planetary orbital axis and the stellar rotation axis should be λ = 70° ± 15° to be compatible with our observations. This suggests that some close-in planets might result from gravitational interaction between planets and/or stars rather than migration due to interaction with the accretion disk. This surprising result requires confirmation by additional observations, especially at lower airmass, to fully exclude the possibility that the signal is due to systematic effects.