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

Article

关键词: TRANSITING PLANET;    EXTRASOLAR;    EVOLUTION;    CANDIDATES;   

DOI  :  10.1038/nature08245

来源: SCIE

【 摘 要 】

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(1,2), or by an alternative mechanism such as planet-planet scattering(3). The hot Jupiters closest to their parent stars, at orbital distances of only similar to 0.02 astronomical units, have strong tidal interactions(4,5), and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory(6,7). Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 M-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.

【 授权许可】

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