[en] The `hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only ~0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94days and a mass of ten Jupiter masses (10M[SUB]Jup[/SUB]), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 10[SUP]6[/SUP], as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Hellier, Coel; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Anderson, D. R.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Cameron, A Collier; School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS, UK
Gillon, Michaël ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Hebb, L.; School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS, UK
Maxted, P. F. L.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Queloz, D.; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
Smalley, B.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Triaud, A H M J; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
West, R. G.; Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK
Wilson, D. M.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Bentley, S. J.; Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
Enoch, B.; School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS, UK
Horne, K.; School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS, UK
Irwin, J.; Department of Astronomy, Harvard University, 60 Garden Street, MS 10, Cambridge, Massachusetts 02138, USA
Lister, T. A.; Las Cumbres Observatory, 6740 Cortona Dr. Suite 102, Santa Barbara, California 93117, USA
Mayor, M.; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
Parley, N.; School of Physics and Astronomy, University of St Andrews, North Haugh, Fife, KY16 9SS, UK
Pepe, F.; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
Pollacco, D. L.; Astrophysics Research Centre, School of Mathematics and Physics, Queen's University, University Road, Belfast, BT7 1NN, UK
Segransan, D.; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
Udry, S.; Observatoire de Genève, Université de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
Wheatley, P. J.; Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
Lin, D. N. C., Bodenheimer, P. & Richardson, D. C. Orbital migration of the planetary companion of 51 Pegasi to its present location. Nature 380, 606-607 (1996).
Tanaka, H., Takeuchi, T. & Ward, W. R. Three-dimensional interaction between a planet and an isothermal gaseous disk. I. Corotation and Lindblad torques and planet migration. Astrophys. J. 565, 1257-1274 (2002).
Rasio, F. & Ford, E. B. Dynamical instabilities and the formation of extrasolar planetary systems. Science 274, 954-956 (1996). (Pubitemid 26398410)
Hut, P. Tidal evolution in close binary systems. Astron. Astrophys. 99, 126-140 (1981).
Eggleton, P. P., Kiseleva, L. G. &Hut, P. The equilibrium tide model for tidal friction. Astrophys. J. 499, 853-870 (1998).
Sasselov, D. D. The new transiting planet OGLE-TR-56b: orbit and atmosphere. Astrophys. J. 596, 1327-1331 (2003).
Ogilvie, G. I. & Lin, D. N. C. Tidal dissipation in rotating solar-type stars. Astrophys. J. 661, 1180-1191 (2007).
Pollacco, D. L. et al. The WASP project and the SuperWASP cameras. Publ. Astron. Soc. Pacif. 118, 1407-1418 (2006).
Sahu, K. C. et al. Transiting extrasolar planetary candidates in the Galactic bulge. Nature 443, 534-540 (2006).
Pont, F. et al. A transiting planet among 23 new near-threshold candidates from the OGLE survey - OGLE-TR-182. Astron. Astrophys. 487, 749-754 (2008).
Baraffe, I., Chabrier, G., Allard, F. & Hauschildt, P. H. Evolutionary models for solar metallicity low-mass stars: mass-magnitude relationships and color-magnitude diagrams. Astron. Astrophys. 337, 403-412 (1998).
Hebb, L. et al. WASP-12b: The hottest transiting planet yet discovered. Astrophys. J. 693, 1920-1928 (2009).
Boesgaard, A. M. & Tripicco, M. J. Lithium in the Hyades cluster. Astrophys. J. 302, L49-L53 (1986).
Dobbs-Dixon, I., Lin, D. N. C. & Mardling, R. A. Spin-orbit evolution of short-period planets. Astrophys. J. 610, 464-476 (2004).
Meibom, S. & Mathieu, R. D. A robust measure of tidal circularization in coeval binary populations: the solar-type spectroscopic binary population in the open cluster M35. Astrophys. J. 620, 970-983 (2005). (Pubitemid 40506672)
Goldreich, P. & Soter, S. Q in the Solar System. Icarus 5, 375-389 (1966).
Peale, S. J. Origin and evolution of the natural satellites. Annu. Rev. Astron. Astrophys. 37, 533-602 (1999).
Levrard, B. Winisdoerffer, C. & Chabrier, G. Falling transiting extrasolar giant planets. Astrophys. J. 692, L9-L13 (2009).
Jackson, B., Greenberg, R. & Barnes, R. Tidal heating of extrasolar planets. Astrophys. J. 681, 1631-1638 (2008).
Laughlin, G. et al. Rapid heating of the atmosphere of an extrasolar planet. Nature 457, 562-564 (2009).
Pätzold, M. & Rauer, H. Where are the massive close-in extrasolar planets? Astrophys. J. 568, L117-L120 (2002).
Pätzold, M., Carone, L. & Rauer, H. Tidal interactions of close-in extrasolar planets: The OGLE cases. Astron. Astrophys. 427, 1075-1080 (2004).
Gillon, M. et al. Improved parameters for the transiting hot Jupiters WASP-4b and WASP-5b. Astron. Astrophys. 496, 259-267 (2009).
Israelian, G., Santos, N. C., Mayor, M. & Rebolo, R. Evidence for planet engulfment by the star HD 82943. Nature 411, 163-166 (2001). (Pubitemid 32455169)
van Leeuwen, F. Validation of the new Hipparcos reduction. Astron. Astrophys. 474, 653-664 (2007).
Collier-Cameron, A. et al. WASP-1b and WASP-2b: two new transiting exoplanets detected with SuperWASP and SOPHIE. Mon. Not. R. Astron. Soc. 375, 951-957 (2007).
West, R. et al. The low density transiting exoplanet WASP-15b. Astron. J. 137, 4834-4836 (2009).
