PLANETESIMAL AND PROTOPLANET DYNAMICS IN A TURBULENT PROTOPLANETARY DISK: IDEAL UNSTRATIFIED DISKS
PLANETESIMAL AND PROTOPLANET DYNAMICS IN A TURBULENT PROTOPLANETARY DISK: IDEAL UNSTRATIFIED DISKS
复制标题
湍流原行星盘中的星子和原行星动力学：理想的无分层盘
DOI：
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
K. Menou
中科院分区：
文献类型：
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作者：
Chao;M. Mac Low;K. Menou
行星体和行星核的动力学可能受到其原始行星气盘中磁转湍流驱动的密度微扰的强烈影响。利用局部剪切盒近似，数值模拟了星子作为无质量粒子在湍流、磁化、非分层气体圆盘中的运动。我们的基准盘模型显示了湍流吸积，其特征参数为α∼10−2，均方根密度扰动为∼10%。我们在模拟中测量了粒子轨道属性的统计演化，包括平均半径、偏心率和速度色散。我们证实了所有这三个性质在时间上的随机游动增长，这是第一次在局部模型中用直接轨道积分来完成这一点。我们发现，当水平尺寸至少达到8个标度高度的盒子时，增长率随着盒子大小的增加而增加。然而，即使是我们最大的盒子也显示出足够低的速度色散，以至于在内盘的整个生命周期中，小行星的碰撞破坏应该不重要。我们的直接积分与早期的扭矩测量结果一致，表明对于行星核和类地行星质量范围内的大多数物体，I型迁移通过随机扭矩主导扩散迁移。对于千米大小的行星体质量范围内的天体来说，扩散迁移仍然很重要。在对磁旋转不稳定盘的局部和全球模拟之间得出的湍流大小之间的差异仍然是一个悬而未决的问题，对行星形成的情景具有重要的后果。
The dynamics of planetesimals and planetary cores may be strongly influenced by density perturbations driven by magneto-rotational turbulence in their natal protoplanetary gas disks. Using the local shearing box approximation, we perform numerical simulations of planetesimals moving as massless particles in a turbulent, magnetized, unstratified gas disk. Our fiducial disk model shows turbulent accretion characterized by a Shakura–Sunyaev viscosity parameter of α ∼ 10−2, with rms density perturbations of ∼10%. We measure the statistical evolution of particle orbital properties in our simulations including mean radius, eccentricity, and velocity dispersion. We confirm random walk growth in time of all three properties, the first time that this has been done with direct orbital integration in a local model. We find that the growth rate increases with the box size used at least up to boxes of eight scale heights in horizontal size. However, even our largest boxes show velocity dispersions sufficiently low that collisional destruction of planetesimals should be unimportant in the inner disk throughout its lifetime. Our direct integrations agree with earlier torque measurements showing that type I migration dominates over diffusive migration by stochastic torques for most objects in the planetary core and terrestrial planet mass range. Diffusive migration remains important for objects in the mass range of kilometer-sized planetesimals. Discrepancies in the derived magnitude of turbulence between local and global simulations of magneto-rotationally unstable disks remains an open issue, with important consequences for planet formation scenarios.
DOI：
10.1088/0004-637x/691/2/l133
发表时间：
2009-02
期刊：
The Astrophysical Journal
影响因子：
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作者：
S. Stewart;Z. Leinhardt
通讯作者：
S. Stewart;Z. Leinhardt
灾难性小天体碰撞的全面数值模拟
影响因子：
3.2
作者：
Leinhardt Z
通讯作者：
Leinhardt Z
DOI：
10.1088/2041-8205/715/2/l68
发表时间：
2010-03
期刊：
The Astrophysical Journal Letters
影响因子：
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作者：
W. Lyra;S. Paardekooper;M. Mac Low
通讯作者：
W. Lyra;S. Paardekooper;M. Mac Low