Gas accretion onto a protoplanet and formation of a gas giant planet
Gas accretion onto a protoplanet and formation of a gas giant planet
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DOI：
10.1111/j.1365-2966.2010.16527.x
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发表时间：
2010-02
影响因子：
4.8
通讯作者：
M. Machida;E. Kokubo;S. Inutsuka;Tomoaki Matsumoto
中科院分区：
文献类型：
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作者：
M. Machida;E. Kokubo;S. Inutsuka;Tomoaki Matsumoto
在三维流体力学模拟中，考虑了气体的热效应，研究了原行星气体盘到类木半径行星的广泛区域，采用嵌套网格方法进行了解析。我们估计了气态巨行星的质量吸积速率和生长时间尺度。Mp Mcri的质量吸积率随原行星质量的增加而增加，其中Mcri≡0.036 MJup(ap/1au) 0.75， MJup和ap分别是木星的质量和轨道半径。这种吸积速率通常比二维模拟中的要小两个数量级。气态巨行星的生长时间尺度或气体吸积到原行星的时间尺度约为105年，比固体地核的生长时间尺度短两个数量级。热效应几乎不影响质量吸积率，因为引力能主导了原行星周围的热能。我们在局部模拟中得到的质量吸积率在数量上与在较粗空间分辨率的全局模拟中得到的结果一致。质量吸积速率主要由原行星的质量和原行星盘的性质决定。我们发现，当Hill或Bondi半径得到充分分解时，质量吸积率就能得到正确的计算。利用原行星的寡头生长理论，讨论了气态巨行星形成的时间尺度。
We investigate gas accretion on to a protoplanet, by considering the thermal effect of gas in three-dimensional hydrodynamical simulations, in which the wide region from a protoplanetary gas disc to a Jovian radius planet is resolved using the nested grid method. We estimate the mass accretion rate and growth time-scale of gas giant planets. The mass accretion rate increases with protoplanet mass for Mp M cri, where Mcri ≡ 0.036 MJup(ap/1au) 0.75 , and MJup and ap are the Jovian mass and the orbital radius, respectively. This accretion rate is typically two orders of magnitude smaller than that in two-dimensional simulations. The growth time-scale of a gas giant planet or the time-scale of the gas accretion on to the protoplanet is about 10 5 yr, that is two orders of magnitude shorter than the growth time-scale of the solid core. The thermal effects barely affect the mass accretion rate because the gravitational energy dominates the thermal energy around the protoplanet. The mass accretion rate obtained in our local simulations agrees quantitatively well with those obtained in global simulations with coarser spatial resolution. The mass accretion rate is mainly determined by the protoplanet mass and the property of the protoplanetary disc. We find that the mass accretion rate is correctly calculated when the Hill or Bondi radius is sufficiently resolved. Using the oligarchic growth of protoplanets, we discuss the formation time-scale of gas giant planets.