CAPTURE AND EVOLUTION OF PLANETESIMALS IN CIRCUMJOVIAN DISKS

We study the evolution of planetesimals in evolved gaseous disks that orbit a solar-mass star and harbor a Jupitermass planet at a_p ≈ 5 AU. The gas dynamics are modeled with a three-dimensional hydrodynamics code that employs nested grids and achieves a resolution of one Jupiter radius in the circumplanetary disk. The code models solids as individual particles. Planetesimals are subjected to gravitational forces by the star and the planet, a drag force by the gas, disruption via ram pressure, and mass loss through ablation. The mass evolution of solids is calculated self-consistently with their temperature, velocity, and position. We consider icy and icy/rocky bodies of radius 0.1-100 km, initially deployed on orbits around the star within a few Hill radii (R_H) of the planet's orbit. Planetesimals are scattered inward, outward, and toward disk regions of radius r 蠑 a_p. Scattering can relocate significant amounts of solids, provided that regions |r - a_p| ∼ 3R_H are replenished with planetesimals. Scattered bodies can be temporarily captured on planetocentric orbits. Ablation consumes nearly all solids at gas temperatures ≲220 K. Super-Keplerian rotation around and beyond the outer edge of the gas gap can segregate ≲0.1 km bodies, producing solid gap edges at size-dependent radial locations. Capture, break-up, and ablation of solids result in a dust-laden circumplanetary disk with low surface densities of kilometer sized planetesimals, implying relatively long timescales for satellite formation. After a giant planet acquires most of its mass, accretion of solids is unlikely to significantly alter its heavy element content. The luminosity generated by accretion of solids and the contraction luminosity can be of similar orders of magnitude.