**34th Meeting of the AAS Division on Dynamical Astronomy, May 2003**

* 12 Migration and Others*

Oral, Wednesday, May 7, 2003, 10:50am-12:35pm,
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## [12.01] Migration and Dynamical Relaxation in Crowded Systems of Giant Planets

*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.