* Astronomy

Title: Core-Accretion Model Predicts Few Jovian-Mass Planets Orbiting Red Dwarfs
Authors: Gregory Laughlin, Peter Bodenheimer, Fred C. Adams
15 Jul 2004

The favoured theoretical explanation for giant planet formation -- in both our solar system and others -- is the core accretion model (although it still has some serious difficulties). In this scenario, planetesimals accumulate to build up planetary cores, which then accrete nebular gas. With current opacity estimates for protoplanetary envelopes, this model predicts the formation of Jupiter-mass planets in 2--3 Myr at 5 AU around solar-mass stars, provided that the surface density of solids is enhanced over that of the minimum-mass solar nebula (by a factor of a few). Working within the core-accretion paradigm, this paper presents theoretical calculations which show that the formation of Jupiter-mass planets orbiting M dwarf stars is seriously inhibited at all radial locations (in sharp contrast to solar-type stars). Planet detection programs sensitive to companions of M dwarfs will test this prediction in the near future.

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Ed ~ The question of which of the two models Core Accretion or Disk Instability is correct may be answered by the WFCAM Transit Survey in the near future.

The WFCAM Transit Survey (PIs Hodgkin & Pinfield) has been awarded 200 nights of UKIRT time to perform the first ever systematic near-infrared search for transiting exo-planets around cool dwarfs. Observations started in the summer of 2007, and sufficient data now exists to begin preliminary searches for transits and eclipses for those fields with the best coverage.
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