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Post Info TOPIC: WASP-22b


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RE: WASP-22b
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Title: Spin-orbit measurements and refined parameters for the exoplanet systems WASP-22 and WASP-26
Authors: D. R. Anderson, A. Collier Cameron, M. Gillon, C. Hellier, E. Jehin, M. Lendl, D. Queloz, B. Smalley, A. H. M. J. Triaud, M. Vanhuysse

We report on spectroscopic and photometric observations through transits of the exoplanets WASP-22b and WASP-26b, intended to determine the systems' spin-orbit angles. We combine these data with existing data to refine the system parameters. We measure a sky-projected spin-orbit angle of 22 16 deg for WASP-22b, showing the planet's orbit to be prograde and, perhaps, slightly misaligned. We do not detect the Rossiter-McLaughlin effect of WASP-26b due to its low amplitude and observation noise. We place 3-sigma upper limits on orbital eccentricity of 0.063 for WASP-22b and 0.050 for WASP-26b. After refining the drift in the systemic velocity of WASP-22 found by Maxted et al. (2010) we find the third body in the system to have a separation-scaled minimum-mass of 0.21 0.01 Mjup/AU/AU.

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Title: WASP-22 b: A transiting "hot Jupiter" planet in a hierarchical triple system
Authors: P. F. L. Maxted (1), D. R. Anderson (1), M. Gillon (2 and 3), C. Hellier (1), D. Queloz (2), B. Smalley (1), A. H. M. J. Triaud (2), R. G. West (4), D. M. Wilson (1), S. J. Bentley (1), H. Cegla (1,5,9), A. Collier Cameron (5), B. Enoch (5), L. Hebb (5), K. Horne (5), J. Irwin (6), T. A. Lister (7), M. Mayor (2), N. Parley (5), F. Pepe (2) D. Pollacco (8), D. Segransan (2), S. Udry (2), P. J. Wheatley (9)
(Version v2)

We report the discovery of a transiting planet orbiting the star TYC 6446-326-1. The star, WASP-22, is a moderately bright (V=12.0) solar-type star (Teff = 6000 100 K, [Fe/H] = -0.05 0.08). The lightcurve of the star obtained with the WASP-South instrument shows periodic transit-like features with a depth of about 1 and a duration of 0.14 days. The presence of a transit-like feature in the lightcurve is confirmed using z-band photometry obtained with Faulkes Telescope South. High resolution spectroscopy obtained with the CORALIE and HARPS spectrographs confirm the presence of a planetary mass companion with an orbital period of 3.533 days in a near-circular orbit. From a combined analysis of the spectroscopic and photometric data assuming that the star is a typical main-sequence star we estimate that the planet has a mass M_p = 0.56 0.02 M_Jup and a radius R_p = 1.12 0.04 R_Jup. In addition, there is a linear trend of 40 m/s/yr in the radial velocities measured over 16 months, from which we infer the presence of a third body with a long period orbit in this system. The companion may be a low mass M-dwarf, a white dwarf or a second planet.

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