37th DPS Meeting, 4-9 September 2005
Session 25 Planet and Satellite Formation
Oral, Tuesday, September 6, 2005, 2:00-3:50pm, Law LG19

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[25.01] The Role of Dynamical Friction in Terrestrial Planet Formation

H. Levison, D. Nesvorny (SwRI), C. Agnor (UCSC), A. Morbidelli (Nice Obs.)

Models of the late stages of terrestrial planet formation produce planets that typically have orbital eccentricities substantially larger than those of Earth and Venus. It as been suggested that these discrepancies are due, at least in part, to the fact that these simulations did not adequately account for the presence of a massive swarm of small (R\ll 1,000km) planetesimals and collisional fragments that should persist throughout planetary accretion. The main effect of these objects would be to damp down eccentricities and inclinations of the embryos. We have developed a new algorithm which allows us to include a large number of small objects in terrestrial formation simulations. These small bodies are represented by a relatively small number (~00) of 'tracer' particles whose orbits are calculated directly, while the dynamical effect of the tracers on the embryos is calculated assuming that each tracer represents a large number of small bodies with similar orbits. If a particular tracer crosses the orbit of a planet, the code applies a drag force to the planet that mimics its response to this assemblage of particles. Preliminary simulations using this new algorithm suggest that the inclusion of dynamical friction may indeed solve the eccentricity problem described above.

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.