N-Body Simulation of Planetesimal Formation through Gravitational Instability of a Dust Layer in Laminar Gas Disk
N-Body Simulation of Planetesimal Formation through Gravitational Instability of a Dust Layer in Laminar Gas Disk
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通过层流气盘中尘埃层的引力不稳定性对行星形成的 N 体模拟
DOI：
10.1088/0004-637x/719/2/1021
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发表时间：
2010
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.
我们利用局部 N 体模拟，通过气盘中的引力不稳定性来研究尘埃层中星子的形成过程。气体被建模为背景层流。我们研究星子的形成过程及其对气体阻力强度的依赖性。我们的模拟结果表明，形成过程定性地分为三个阶段：尾流状密度结构的形成、星子种子的产生及其碰撞生长。耗散引力不稳定性的线性分析表明，尽管Toomre的Q值大于1，但尘埃层是长期不稳定的。但在初始阶段，重力失稳的增长时间长于粉尘沉降和速度弥散下降的时间。因此，速度分散减小并且圆盘垂直收缩。当速度色散变得足够小时，重力不稳定最终成为主导。然后由于重力不稳定性而形成尾流状密度结构。这些结构分裂成星子种子。种子因相互碰撞而迅速生长。
We investigate the formation process of planetesimals from the dust layer by the gravitational instability in the gas disk using local N-body simulations. The gas is modeled as a background laminar flow. We study the formation process of planetesimals and its dependence on the strength of the gas drag. Our simulation results show that the formation process is divided into three stages qualitatively: the formation of wake-like density structures, the creation of planetesimal seeds, and their collisional growth. The linear analysis of the dissipative gravitational instability shows that the dust layer is secularly unstable although Toomre's Q value is larger than unity. However, in the initial stage, the growth time of the gravitational instability is longer than that of the dust sedimentation and the decrease in the velocity dispersion. Thus, the velocity dispersion decreases and the disk shrinks vertically. As the velocity dispersion becomes sufficiently small, the gravitational instability finally becomes dominant. Then wake-like density structures are formed by the gravitational instability. These structures fragment into planetesimal seeds. The seeds grow rapidly owing to mutual collisions.