An orbital period of 0.94days for the hot-Jupiter planet WASP-18b

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

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Abstract

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 (10MJup), 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 106, 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.
Original languageEnglish
Pages (from-to)1098-1100
Number of pages3
JournalNature
Volume460
Issue number7259
DOIs
Publication statusPublished - 27 Aug 2009

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    Hellier, C., Anderson, D. R., Cameron Collier, A., Gillon, M., Hebb, L., Maxted, P. F. L., Queloz, D., Smally, B., Triaud, A. H. M. J., West, R. G., Wilson, D. G., Bentley, S. J., Enoch, B., Horne, K., Irwin, J., Lister, T. A., Mayor, M., Parley, N., Pepe, F., ... Wheatley, P. (2009). An orbital period of 0.94days for the hot-Jupiter planet WASP-18b. Nature, 460(7259), 1098-1100. https://doi.org/10.1038/nature08245