Planetesimal dynamics in the presence of a giant planet II – the dependence of outer planetesimal orbits on planet mass and eccentricity
speaker: Kangrou Guo
Abstract:
The presence of an existing planet embedded in the protoplanetary disk has mixed influence on the growth of other planetary embryos. Gravitational perturbation from the planet can increase the relative velocities of planetesimals at the mean motion resonances to very high values and impede accretion at those locations. However, it can also align the orbital pericenters of planetesimals in certain regions of the disk and thus make them dynamically quiet and “accretion-friendly” locations for planetary growth. Following the previous paper, where we investigated the effect of a Jupiter-like planet on an external planetesimal disk, we generalize our findings to extrasolar planetary systems by varying the planet parameters. In particular, we focus on the dependence of the planetesimal relative velocities on the mass and eccentricity of the existing planet. We found that the velocity dispersion of identical-mass particles increases monotonically with increasing planet mass. Meanwhile, the dependence of the relative velocity between different-mass planetesimals on their mass ratio becomes weaker as the planet mass increases. While the relative velocity generally increases with increasing planet eccentricity, the velocity dispersion of smaller-mass particles ($m \lesssim 10^{18}~\rm{g}$) is almost independent of planet eccentricity owing to their strong coupling to the nebula gas. The results suggest that in a protoplanetary disk with a massive planet ($\gtrsim M_{\rm{Jup}}$) in presence, subsequent planet formation can be challenging. Our results could provide some clues for the formation of Saturn’s core and the orbital features of extrasolar cold giant planets.