In this paper we extend our numerical method for simulating terrestrialplanet formation from Leinhardt and Richardson (2005) to include dynamicalfriction from the unresolved debris component. In the previous work weimplemented a rubble pile planetesimal collision model into direct N-bodysimulations of terrestrial planet formation. The new collision model treatedboth accretion and erosion of planetesimals but did not include dynamicalfriction from debris particles smaller than the resolution limit for thesimulation. By extending our numerical model to include dynamical friction fromthe unresolved debris, we can simulate the dynamical effect of debris producedduring collisions and can also investigate the effect of initial debris mass onterrestrial planet formation. We find that significant initial debris mass, 10%or more of the total disk mass, changes the mode of planetesimal growth.Specifically, planetesimals in this situation do not go through a runawaygrowth phase. Instead they grow concurrently, similar to oligarchic growth. Inaddition to including the dynamical friction from the unresolved debris, wehave implemented particle tracking as a proxy for monitoring compositionalmixing. Although there is much less mixing due to collisions and gravitationalscattering when dynamical friction of the background debris is included, thereis significant inward migration of the largest protoplanets in the most extremeinitial conditions.
展开▼
