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T. Tanigawa (Dept. of Earth and Planetary Sciences, Nagoya Univ.), S. Watanabe (Graduate School of Environmental studies, Nagoya Univ.)
We investigate the gas accretion flow onto the giant protoplanet from a protoplanetary disk in detail in order to clarify the gas capturing process of the giant planet after the onset of gravitational instability of the proto atmosphere of the planet. We adopt local Cartesian coordinates and use the NIRVANA code, which equips nested-grids solver, to obtain accretion flow pattern with high resolution.
Followings are the main features of the flow we obtained. (1)Out of the Hill sphere: The gas approaching to the planet with Keplerian shear velocity forms a bow shock around the Hill sphere by the planetary gravity. The shock surface leans back-ward, so that the almost all gas except around the mid plane gets positive momentum in z-direction when the gas passes the shock. (2)The accretion flow into the Hill sphere: On the mid plane, the gas loses its energy on the bow-shock surface and enters the Hill sphere passing around one of the Lagrangian points on the Hill sphere. Then the gas starts rotating around the planet by Coriolis force and forms a circum-planetary disk. The gas in the disk loses its angular momentum around the planet at the shock surface and migrates inward. On the other hand, there exists the gas originally floating up from the mid plane can accrete directly on the circum-planetary disk. The gas which gained upward momentum at the bow shock dynamically falls onto the disk. A part of the gas leaps up again at the spiral-shock surface in the disk, but the major part can migrate inward losing its angular momentum at the spiral shock without leaping up.
This work was supported by the JSPS Research Fellowships for Young Scientists.
The author(s) of this abstract have provided an email address for comments about the abstract: tanigawa@eps.nagoya-u.ac.jp