PLANET FORMATION FROM PLANETESIMALS ANDDIVERSITY OF PLANETARY SYSTEMS

摘要

Here, gravitational scattering of planetesimals (viscous stir-ring and dynamical friction) and their growth through pairwise colli-sions (runaway/oligarchic growth) are explained in detail. The masses of accreted protoplanets depend on initial disk surface density and semi-major axis. When the mass of a protoplanet becomes larger than a critical value that is a few to ten earth masses, runaway gas accretion from the disk onto the planet starts. The dependence of the protoplanet masses is responsible for the diversity of extrasolar planetary systems, although orbital migrations of planets are also important drivers to produce the diversity.