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

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

Research output: Contribution to journalArticlepeer-review

155 Citations (Scopus)


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$_Jup$), 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$^6$, 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
Publication statusPublished - 1 Aug 2009


Dive into the research topics of 'An orbital period of 0.94days for the hot-Jupiter planet WASP-18b'. Together they form a unique fingerprint.

Cite this