The Gaseous Flow around a Protoplanet in the Primordial Solar Nebula

Two dimensional stationary gaseous flow around a protoplanet in the primordial solar nebula is studied numerically. When the protoplanet revolves with a small eccentricity, flow pattern in the vicinity of the protoplanet is divided into three: Inside a belt which encloses the orbit of the protoplanet and has a width of four times as large as the Hill radius, the inflow gas is attracted by the protoplanet and returns back along the hairpin curve owing to the Coriolis force. Out of this belt, the gas element passes by straightly. The gas element within the Hill sphere of the protoplanet forms an atmosphere rotating in a prograde direction with smaller velocity than the Keplerian velocity around the protoplanet. After a planetary mass has exceeded one-tenth of the present Jupiter's mass, two wings of weak shock waves appear in the pass-by flow region. It is to be noticed that at a time of encounters with planetesimals, a gas element on the hairpin flows changes its orbital radius around the Sun randomly and migrates in the solar nebula radially. The migration time of the gas which makes up the mantle component of the Jupiter is estimated to be about 2×107 yrs.