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F. C. Adams (U. Michigan)
This talk discusses the intermediate-time dynamics of newly formed solar systems with a focus on planetary migration. We consider two limiting corners of parameter space -- crowded systems containing N=10 giant planets in the outer solar system and solar systems with N=2 planets that tidally interact with a circumstellar disk. Crowded planetary systems can form via gravitational instabilities and in accumulation scenarios -- if the disk is metal rich and has a large mass. The planetary system adjusts itself toward stability by spreading out, ejecting planets, and sending bodies into the star. For a given set of initial conditions, dynamical relaxation leads to a well-defined distribution of possible solar systems. For each class of initial conditions, we perform large numbers of N-body simulations to obtain a statistical description of the possible outcomes. For N=10 planet systems, we consider several different planetary mass distributions; we also perform secondary sets of simulations to explore chaotic behavior and longer term dynamics. For systems with 10 planets initially populating the range 5 AU < a < 30 AU, these scattering processes naturally produce orbits with a=1 AU and the full range of eccentricity. Shorter period orbits (smaller a) are more difficult to achieve. To account for the observed eccentric giant planets, we explore an alternate mechanism that combines dynamical scattering and tidal interactions with a circumstellar disk. This combined model naturally produces the observed range of semi-major axis and eccentricity. We discuss the relative merits of the different migration mechanisms for producing the observed eccentric giant planets.
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Bulletin of the American Astronomical Society, 35 #4
© 2003. The American Astronomical Soceity.