AAS 205th Meeting, 9-13 January 2005
Session 29 Planetary Systems and Origins of Planetary Bodies
Oral, Monday, January 10, 2005, 10:00-11:30am, Town and Country

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[29.02] Seeding giant planets: Interactions between gap-opening and sub-gap-opening bodies in a protoplanetary disk

E. W. Thommes (CITA, University of Toronto)

Young planets interact with their parent gas disk through tidal torques. An imbalance between inner and outer torques causes bodies the mass of gas giant solid cores, ~10 Earth masses, to undergo orbital decay on a timescale generally short compared to their formation time ("Type I" migration). This makes the first stage of giant planet formation problematic; however, bodies which do manage to reach gas giant size, O(102 Earth masses), open a gap in the disk and subsequently migrate more slowly, locked into the disk's viscous evolution ("Type II" migration). In a young planetary system, both types of bodies likely coexist, and differential migration can result in close encounters between them. We numerically investigate the resulting dynamics and find, as has been previously suggested (Hahn & Ward 1996, LPI 27), that sub-gap-opening bodies have a high likelihood of being resonantly captured when they encounter a gap-opening body. A gas giant planet thus tends to act as a barrier in the disk, stopping smaller, faster-migrating protoplanets outside of its orbit. In this way, one gas giant may facilitate the formation and survival of the next gas giant's core.

This work is supported by the National Sciences and Engineering Resarch Council of Canada.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.