Discovery and characterization of WASP-6b, an inflated sub-Jupiter mass planet transiting a solar-type star

M. Gillon; D. R. Anderson; A. H. M. J. Triaud; C. Hellier; P. F. L. Maxted; D. Pollaco; D. Queloz; B. Smalley; R. G. West; D. M. Wilson; S. J. Bentley; A. Collier Cameron; B. Enoch; L. Hebb; K. Horne; J. Irwin; Y. C. Joshi; T. A. Lister; M. Mayor; F. Pepe; N. Parley; D. Segransan; S. Udry; P. J. Wheatley

doi:10.1051/0004-6361/200911749

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arXiv · 0901.4705

Discovery and characterization of WASP-6b, an inflated sub-Jupiter mass planet transiting a solar-type star

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Abstract

We report the discovery of WASP-6b, an inflated sub-Jupiter mass planet transiting every 3.3610060 +0.0000022-0.0000035 days a mildly metal-poor solar-type star of magnitude V=11.9. A combined analysis of the WASP photometry, high-precision followup transit photometry and radial velocities yield a planetary mass M_p = 0.503 +0.019-0.038 M_jup and radius R_p = 1.224 +0.051-0.052 R_jup, resulting in a density rho_p = 0.27 +-0.05 rho_jup. The mass and radius for the host star are M_s = 0.88 +0.05-0.08 M_sun and R_s = 0.870 +0.025-0.036 R_sun. The non-zero orbital eccentricity e = 0.054 +0.018-0.015 that we measure suggests that the planet underwent a massive tidal heating ~1 Gyr ago that could have contributed to its inflated radius. High-precision radial velocities obtained during a transit allow us to measure a sky-projected angle between the stellar spin and orbital axis Beta = 11 +14-18 deg. In addition to similar published measurements, this result favors a dominant migration mechanism based on tidal interactions with a protoplanetary disk.

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M. Gillon, D. R. Anderson, A. H. M. J. Triaud, C. Hellier, P. F. L. Maxted, D. Pollaco, D. Queloz, B. Smalley, R. G. West, D. M. Wilson, S. J. Bentley, A. Collier Cameron, B. Enoch, L. Hebb, K. Horne, J. Irwin, Y. C. Joshi, T. A. Lister, M. Mayor, F. Pepe, N. Parley, D. Segransan, S. Udry, P. J. Wheatley. 2009-01-29. Discovery and characterization of WASP-6b, an inflated sub-Jupiter mass planet transiting a solar-type star. https://doi.org/10.1051/0004-6361/200911749

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