12:00 〜 12:15
[PAE17-06] Planetesimal dynamics in the presence of a giant planet
キーワード：Protoplanetary disk, dynamics, exoplanets
The presence of an existing planet embedded in the protoplanetary disk has mixed influence on the growth of other planetary embryos. The gravitational perturbation from the planet can increase the random encounter velocity of planetesimals at the mean motion resonances to very high values and impede accretion at those locations. On the other hand, it can also align the orbital pericenter of planetesimals in certain region 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 random encounter velocity 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 encounter velocity between different-mass planetesimals on their mass ratio becomes weaker as the planet mass increases. While the relative encounter velocity generally increases with increasing planet eccentricity, the velocity dispersion of smaller-mass particles (smaller than 1018) is almost independent of planet eccentricity due to their strong coupling to the nebula gas. The results suggest that in a protoplanetary disk with a massive planet (larger than MJup) embedded in, subsequent planet formation might be challenging. Such an implication has some reference value for the explanation of the so-called Kepler dichotomy, which features two distinct populations of planetary systems hosting multiple small planets and those with single giant planets.