Gas accretion on to planetary cores: three-dimensional self-gravitating radiation hydrodynamical calculations
Gas accretion on to planetary cores: three-dimensional self-gravitating radiation hydrodynamical calculations
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DOI：
10.1111/j.1365-2966.2008.14184.x
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发表时间：
2008-11
影响因子：
4.8
通讯作者：
Ben A. Ayliffe;M. Bate
中科院分区：
文献类型：
--
作者：
Ben A. Ayliffe;M. Bate
我们目前的结果从三维，自引力辐射流体动力学模型的气体吸积行星的核心。在某些情况下，吸积流被分解到固体核心的表面--这是第一次进行此类模拟。我们调查的气体吸积率的行星核心质量，表面密度和不透明度的包围原行星盘的依赖关系。微行星的吸积被忽略。我们发现，高质量的原行星周围的厚circumplanetary光盘在其气体吸积阶段，但相反的本地等温计算，光盘不形成周围吸积原行星与质量50 M <$时，辐射流体动力学模拟进行，即使颗粒不透明度从星际值减少了100倍。我们发现，气体的不透明度起着很大的作用，在确定吸积率低质量的行星核心。例如，将不透明度从星际值减少100倍，会导致10-20 M的原行星的吸积率增加大约一个数量级。不透明度的依赖性变得不那么重要，在确定更大质量的核心，重力占主导地位的热支持的影响和原行星基本上是在失控的速度吸积率。增加核心质量从10到100 M/s，增加吸积率的一个因素的50倍的星际不透明。超过100 M，原行星盘为吸积的原行星提供物质的能力限制了吸积速率，与不透明度无关。最后，对于低质量的行星核（20 M），我们得到的吸积率与以前的一维准静态模型一致。这表明，三维流体动力学效应可能不会显着改变气体吸积的时间尺度，已获得准静态模型。
We present results from three-dimensional, self-gravitating radiation hydrodynamical models of gas accretion by planetary cores. In some cases, the accretion flow is resolved down to the surface of the solid core – the first time such simulations have been performed. We investigate the dependence of the gas accretion rate upon the planetary core mass, and the surface density and opacity of the encompassing protoplanetary disc. Accretion of planetesimals is neglected. We find that high-mass protoplanets are surrounded by thick circumplanetary discs during their gas accretion phase but, contrary to locally isothermal calculations, discs do not form around accreting protoplanets with masses 50M⊕ when radiation hydrodynamical simulations are performed, even if the grain opacity is reduced from interstellar values by a factor of 100. We find that the opacity of the gas plays a large role in determining the accretion rates for low-mass planetary cores. For example, reducing the opacities from interstellar values by a factor of 100 leads to roughly an order of magnitude increase in the accretion rates for 10–20 M⊕ protoplanets. The dependence on opacity becomes less important in determining the accretion rate for more massive cores where gravity dominates the effects of thermal support and the protoplanet is essentially accreting at the runaway rate. Increasing the core mass from 10 to 100 M⊕ increases the accretion rate by a factor of ≈50 for interstellar opacities. Beyond ∼100 M⊕, the ability of the protoplanetary disc to supply material to the accreting protoplanet limits the accretion rate, independent of the opacity. Finally, for low-mass planetary cores (20M⊕), we obtain accretion rates that are in agreement with previous one-dimensional quasi-static models. This indicates that three-dimensional hydrodynamical effects may not significantly alter the gas accretion time-scales that have been obtained from quasi-static models.