论文标题
湍流设置了行星形成的长度尺度：局部2D流媒体不稳定性和行星形成的模拟
Turbulence sets the length scale for planetesimal formation: Local 2D simulations of streaming instability and planetesimal formation
论文作者
论文摘要
Trans-Neptunian对象2014 MU69名为Arrokoth，是最新的证据，表明行星可能不是通过较小物体的连续碰撞而形成的，而是通过卵石云的直接重力崩溃而形成的。但是，什么过程设置了可能发生这种崩溃的物理量表呢？恒星形成具有牛仔裤质量，那就是重力比热压强，帮助我们了解太阳的质量。但是，在行星形成的情况下，是什么控制质量和大小？小行星和库珀带对物体的大小分布在100 km处都有扭结。在这里，我们得出了卵石云的重力塌陷标准，这些标准碎片到行星上的碎片，表明需要一个临界质量才能克服湍流扩散。我们成功地测试了该标准在由流不稳定性触发的行星形成的直接数值模拟中。因此，我们的结果可以解释在文献中流媒体不稳定性模拟中发现的行星尺寸，同时无法解决详细的尺寸分布。我们发现，观察到的$ \ sim $ 100 km的特征直径对应于卵石云的临界质量，这是由于湍流扩散的强度而引起的，这是由于流媒体不稳定性的不稳定，即在2-60 au的广泛区域，从2-60 au的广泛区域中，趋势允许在近期和近期较小的物体下，当时较小的物体会耗尽烟熏气体的较小物体。
The trans-Neptunian object 2014 MU69, named Arrokoth, is the most recent evidence that planetesimals did not form by successive collisions of smaller objects, but by the direct gravitational collapse of a pebble cloud. But what process sets the physical scales on which this collapse may occur? Star formation has the Jeans mass, that is when gravity is stronger than thermal pressure, helping us to understand the mass of our sun. But what controls mass and size in the case of planetesimal formation? Both asteroids and Kuiper belt objects show a kink in their size distribution at 100 km. Here we derive a gravitational collapse criterion for a pebble cloud to fragment to planetesimals, showing that a critical mass is needed for the clump to overcome turbulent diffusion. We successfully tested the validity of this criterion in direct numerical simulations of planetesimal formation triggered by the streaming instability. Our result can, therefore, explain the sizes for planetesimals found forming in streaming instability simulations in the literature, while not addressing the detailed size distribution. We find that the observed characteristic diameters of $\sim$ 100 km correspond to the critical mass of a pebble cloud set by the strength of turbulent diffusion stemming from streaming instability for a wide region of a solar nebula model from 2 - 60 au, with a tendency to allow for smaller objects at distances beyond and at late times, when the nebula gas gets depleted.
