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Paper: Dynamics of Gaseous Disks with Planets
Volume: 324, Debris Disks and the Formation of Planets: A Symposium in Memory of Fred Gillett
Page: 39
Authors: Artymowicz, P.
Abstract: We review several theories of origin and evolution of the recently discovered extrasolar planetary systems. The properties of these systems were unexpected. This motivated theorists to extend and revise many preexisting theories. Important extensions include migration of bodies and planetary eccentricity pumping by planet-planet interaction, and primordial disk-planet interaction. Progress in observational techniques might allow us to find which of these two types of interaction is mainly responsible for the observed variety of orbits and exoplanet masses. New insights into the formation of our own system can be gained by asking why Jupiter and Saturn are not larger, closer to the sun and/or do not follow noticeably elliptic orbits. Scenarios of planet migration in disks may change markedly on account of a new mode of migration, which does not have a predetermined direction in a given protoplanetary disk, provided it has zones of low and high density. We present the first simulations of planets undergoing a rapid (runaway) migration. Migration can be inward or outward, depending on the initial disk density distribution. The process is driven by corotational gas flows and orbital libration of underdense disk gas, rather than the previously considered Lindblad resonances or disk viscosity. With characteristic time scale <100 orbital periods in realistically dense disks, runaway migration can be stopped by density gradients, e.g., at the inner boundary of the magnetically inactive 'dead zone' of a protoplanetary disk, located from 0.1 to a few AU from the star.
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