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D. E. Trilling (Univ. Penn.), J. I. Lunine (LPL/Arizona), W. Benz (U. Bern)
We present a statistical study of the post-formation migration of giant planets in a variety of initial disk conditions. For given initial conditions we model the evolution of giant planet orbits under the influence of disk, stellar, and mass loss torques. We determine the mass and semi-major axis distribution of surviving planets after disk dissipation, for various disk lifetimes, viscosities, and initial planet masses. The majority of planets migrate too fast and are destroyed via mass transfer onto the central star. Most surviving planets have relatively large orbital semi-major axes, i.e., several AU or larger. We conclude that the extrasolar planets observed to date, particularly those with small semi-major axes, represent only a small fraction (~10% to 30%) of a larger cohort of giant planets around solar-type stars, and many undetected gaint planets must exist at large (>3~AU) distances from their parent stars. We also find that the planetary initial mass function required to explain the observed extrasolar planets must be strongly biased toward smaller planets. Finally, our simulations imply that the efficiency of giant planet formation must be high: perhaps 30% of solar-type stars possess giant planets during their pre-main sequence phase. These predictions, including those for pre-main sequence stars, are testable with the next generation of ground- and space-based planet detection techniques.