On the Orbit of the Short-period Exoplanet WASP-19b

WASP-19b has the shortest orbital period of any known exoplanet, orbiting at only 1.2 times the Roche tidal radius. By observing the Rossiter-McLaughlin effect we show that WASP-19b's orbit is aligned, with Delta *l = 46 ? 52. Using, in addition, a spectroscopic vsin I and the observed rotation...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2011-04, Vol.730 (2), p.L31-jQuery1323918062020='48'
Main Authors: Hellier, Coel, Anderson, D. R, Collier-Cameron, A, Miller, G. R. M, Queloz, D, Smalley, B, Southworth, J, Triaud, A. H. M. J
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
EVOLUTION
MOTION
ORBITS
PLANETS
ROTATION
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Summary:WASP-19b has the shortest orbital period of any known exoplanet, orbiting at only 1.2 times the Roche tidal radius. By observing the Rossiter-McLaughlin effect we show that WASP-19b's orbit is aligned, with Delta *l = 46 ? 52. Using, in addition, a spectroscopic vsin I and the observed rotation period we conclude that the obliquity, Delta *v, is less than 20?. Further, the eccentricity of the orbit is less than 0.02. We argue that hot Jupiters with orbital periods as short as that of WASP-19b are two orders of magnitude less common than hot Jupiters at the 3-4 day 'pileup.' We discuss the evolution of WASP-19b's orbit and argue that most likely it was first moved to near twice the Roche limit by third-body interactions, and has since spiralled inward to its current location under tidal decay. This is compatible with a stellar tidal-dissipation quality factor, Q'*, of order 107.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/730/2/L31