The spin-orbit alignment of the transiting exoplanet WASP-3b from Rossiter-McLaughlin observations

E. K. Simpson, D. Pollacco, G. Hébrard, N. P. Gibson, S. C. C. Barros, I. Boisse, F. Bouchy, A. Collier Cameron, G. R. M. Miller, C. A. Watson, F. P. Keenan

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We present an observation of the Rossiter-McLaughlin effect for the planetary system WASP-3. Radial velocity measurements were made during transit using the SOPHIE spectrograph at the 1.93-m telescope at Haute-Provence Observatory. The shape of the effect shows that the sky-projected angle between the stellar rotation axis and planetary orbital axis (?) is small and consistent with zero within . WASP-3b joins the ~two-thirds of planets with measured spin-orbit angles that are well aligned and are thought to have undergone a dynamically gentle migration process such as planet-disc interactions. We find a systematic effect which leads to an anomalously high determination of the projected stellar rotational velocity (vsini = 19.6+2.2-2.1kms-1) compared to the value found from spectroscopic line broadening (vsini = 13.4 +/- 1.5kms-1). This is thought to be caused by a discrepancy in the assumptions made in the extraction and modelling of the data. Using a model developed by Hirano et al. designed to address this issue, we find vsini to be consistent with the value obtained from spectroscopic broadening measurements (vsini = 15.7+1.4-1.3kms-1).
Original languageEnglish
Pages (from-to)1867-1872
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Publication statusPublished - 01 Jul 2010

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics


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