Gas dynamics around a Jupiter-mass planet I. Influence of protoplanetary disk properties

Abstract

Giant planets grow and acquire their gas envelope during the disk phase. At the time of the discovery of giant planets in their host disk, it is important to understand the interplay between the host disk and the envelope and circum-planetary disk properties of the planet. Our aim is to investigate the dynamical and physical structure of the gas in the vicinity of a Jupiter-mass planet and study how protoplanetary disk propertiesy, determine the planetary system as well as the accretion rate inside the planet's Hill sphere.We ran global 3D simulations with the grid-based code fargOCA, using a fully radiative equation of state and a dust-to-gas ratio of 0.01. We explored three models. The nominal one features a disk with surface density, Sigma, corresponding to the MMSN at the planet's location, characterised by an alpha viscosity value of 0.004. The second model has a surface density ten times smaller than the nominal one and the same viscosity. In the third model, we also reduced the viscosity value by a factor of 10. During gap formation gas is heated by compression and cools according to opacity, density, and temperature values. In the analysis of our disks, we find that the gas flowing into the Hill sphere is approximately scaled as the product Sigma nu , as expected from viscous transport while The accretion rate is scaled as sqrt(Sigma nu ).Previous studies have shown that pressure or rotationally supported structures are formed around giant planets, depending on the equation of state (EoS) or on the opacity. In the case of a fully radiative EoS and a constant dust to gas ratio of 0.01, we find that low-mass and low-viscosity circum-stellar disks favour the formation of a rotationally supported circum-planetary disk. Gas accretion leading to the doubling time of the planetary system >10^5 years has only been found in the case of a low-viscosity disk.