FINAL MASSES OF GIANT PLANETS. II. JUPITER FORMATION IN A GAS-DEPLETED DISK
FINAL MASSES OF GIANT PLANETS. II. JUPITER FORMATION IN A GAS-DEPLETED DISK
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DOI：
10.3847/0004-637x/823/1/48
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发表时间：
2015-10
期刊：
影响因子：
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通讯作者：
T. Tanigawa;Hidekazu Tanaka
中科院分区：
文献类型：
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作者：
T. Tanigawa;Hidekazu Tanaka
首先，我们采用基于流体动力学模拟的气体俘获率经验公式和浅盘间隙模型，研究了原行星盘中生长的巨行星通过俘获盘气体而形成的最终质量。我们发现，对于质量小于10个木星质量的行星，它们的生长速度主要由通过全球盘吸积提供的气体控制，而间隙的打开并不限制吸积。与快速的气体捕获相比，气体供应不足导致气体表面密度的消耗，甚至在间隙的外部，这可以在圆盘上形成一个内孔。其次，我们的发现应用于太阳系的形成。对于木星的形成，在它的气体捕获开始时，由于持续的捕获，需要一个质量很低的几个木星质量的气体盘。这种具有足够固体物质的低质量气体盘可以由初始尺寸约10 au的致密盘通过粘性演化形成。通过中等粘度为α ~ 10−3的粘性演化，当木星的固体核心在t ~ 107年开始气体捕获时，大部分圆盘气体会吸积到太阳上，并且广泛分布的低质量气体盘仍然存在。一个非常低质量的气体盘也提供了一个合理的路径，在那里I型和II型行星的迁移都被显著抑制。特别是，木星大小的行星的II型迁移变得低效，因为由于这些行星快速捕获气体而导致额外的气体枯竭。
First, we study the final masses of giant planets growing in protoplanetary disks through capture of disk gas, by employing empirical formulae for the gas capture rate and a shallow disk gap model, which are both based on hydrodynamic simulations. We find that, for planets less massive than 10 Jupiter masses, their growth rates are mainly controlled by the gas supply through the global disk accretion, and the gap opening does not limit the accretion. The insufficient gas supply compared with the rapid gas capture causes a depletion of the gas surface density even at the outside the gap, which can create an inner hole in the disk. Second, our findings are applied to the formation of our solar system. For the formation of Jupiter, a very low-mass gas disk of several Jupiter masses is required at the beginning of its gas capture because of the continual capture. Such a low-mass gas disk with sufficient solid material can be formed through viscous evolution from a compact disk of initial size ∼10 au. By viscous evolution with a moderate viscosity of α ∼ 10−3, most of the disk gas accretes onto the Sun and a widely spread low-mass gas disk remains when the solid core of Jupiter starts gas capture at t ∼ 107 yr. A very low-mass gas disk also provides a plausible path where type I and II planetary migrations are both suppressed significantly. In particular, the type II migration of Jupiter-size planets becomes inefficient because of the additional gas depletion due to the rapid gas capture by such planets.