Angular momentum accretion onto a gas giant planet

作者：Machida Masahiro N^*; Kokubo Eiichiro; Inutsuka Shu Ichiro; Matsumoto Tomoaki

来源：Astrophysical Journal, 2008, 685(2): 1220-1236.

DOI：10.1086/590421

• accretion, accretion disks
• hydrodynamics
• planetary systems
• planets and satellites : formation
• solar system : formation

We investigate the accretion of angular momentum onto a protoplanet system using three- dimensional hydrodynamical simulations. We consider a local region around a protoplanet in a protoplanetary disk with sufficiently high spatial resolution. We describe the structure of the gas flow onto and around the protoplanet in detail. We find that the gas flows onto the protoplanet system in the vertical direction, crossing the shock front near the Hill radius of the protoplanet, which is qualitatively different from the picture established by two- dimensional simulations. The specific angular momentum of the gas accreted by the protoplanet system increases with the protoplanet's mass. At a Jovian orbit, when the protoplanet's mass M-p is M-p less than or similar to 1M(Jup), where M-Jup is the Jovian mass, the specific angular momentum increases as j proportional to M-p. On the other hand, it increases as j proportional to M-p(2/3) when the protoplanet's mass is M-p greater than or similar to 1M(Jup). The stronger dependence of the specific angular momentum on the protoplanet's mass for M-p less than or similar to 1M(Jup) is due to the thermal pressure of the gas. The estimated total angular momentum of a system of a gas giant planet and a circumplanetary disk is 2 orders of magnitude larger than those of the present gas giant planets in the solar system. A large fraction of the total angular momentum contributes to the formation of the circumplanetary disk. We also discuss the formation of satellites from the circumplanetary disk.

• 出版日期2008-10-1
• 单位中国科学院国家天文台