Secular Gravitational Instability of a Dust Layer in Shear Turbulence
Secular Gravitational Instability of a Dust Layer in Shear Turbulence
复制标题
剪切湍流中尘埃层的长期引力不稳定性
DOI：
10.1088/0004-637x/746/1/35
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
S.
中科院分区：
文献类型：
--
作者：
Michikoshi;S.;Kokubo;E.;Inutsuka;S.
本文对湍流气盘中的尘埃层进行了线性稳定性分析。Youdin研究了长期的重力不稳定性（GI）的尘埃层使用流体动力学方程与湍流扩散项。我们得到基本上相同的结果独立于Youdin。在目前的分析中，我们限制感兴趣的小尘埃颗粒的区域，同时调查的长期GI在一个更严格的方式。我们讨论了沙尘表面密度分布的时间演化的随机模型，并推导出对流扩散方程。Youdin分析的有效性在强阻力极限下得到了证实。我们定量地表明，有限厚度的尘埃层削弱了长期GI和密度依赖的扩散系数改变的增长率。我们将所得结果应用于剪切不稳定性驱动的湍流，发现当气体密度是最小质量圆盘模型的三倍时，长期GI比径向漂移快。如果尘埃颗粒比球粒大，长期GI在原行星盘的寿命内增长。
We perform a linear stability analysis of a dust layer in a turbulent gas disk. Youdin investigated the secular gravitational instability (GI) of a dust layer using hydrodynamic equations with a turbulent diffusion term. We obtain essentially the same result independently of Youdin. In the present analysis, we restrict the area of interest to small dust particles, while investigating the secular GI in a more rigorous manner. We discuss the time evolution of the dust surface density distribution using a stochastic model and derive the advection–diffusion equation. The validity of the analysis by Youdin is confirmed in the strong drag limit. We demonstrate quantitatively that the finite thickness of a dust layer weakens the secular GI and that the density-dependent diffusion coefficient changes the growth rate. We apply the results obtained to the turbulence driven by the shear instability and find that the secular GI is faster than the radial drift when the gas density is three times as large as that in the minimum-mass disk model. If the dust particles are larger than chondrules, the secular GI grows within the lifetime of a protoplanetary disk.