Testing the Jeans, Toomre, and Bonnor–Ebert Concepts for Planetesimal Formation: 3D Streaming-instability Simulations of Diffusion-regulated Formation of Planetesimals
Testing the Jeans, Toomre, and Bonnor–Ebert Concepts for Planetesimal Formation: 3D Streaming-instability Simulations of Diffusion-regulated Formation of Planetesimals
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测试 Jeans、Toomre 和 Bonnor-Ebert 的小行星形成概念：扩散调节小行星形成的 3D 流不稳定性模拟
DOI：
10.3847/1538-4357/abca9b
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
A. Schreiber
中科院分区：
文献类型：
--
作者：
H. Klahr;A. Schreiber
我们在希尔密度和超越流不稳定性模拟证明，当卵石积累超过当地希尔密度，星子的形成是不完整的。我们发现，希尔密度是不是一个足够的标准进一步引力坍缩的卵石云成一个微行星，但另外的累积质量必须足够大，以克服湍流扩散。系统的Toomre分析表明，线性自引力模式在我们的数值模拟的规模上不起作用。然而，我们发现，自重力，通过垂直收缩卵石层，增加了湍流的强度，这是一个指示的Kelvin-Helmholtz不稳定性或流不稳定性的提升。我们还确定了Bonnor-Ebert中心密度，给定质量的卵石云在能够继续收缩以抵抗内部扩散之前必须被压缩到该中心密度。由于卵石云的等效“固体”尺寸与中心密度的-1/6次方成比例，因此在相同的湍流扩散水平下，100 km等效尺寸的卵石云比10 km的卵石云更容易坍缩。这可以解释太阳系中缺乏小天体的原因，并预测小天体将在大的卵石与气体比例下形成，因此要么在太阳星云的外围，要么在气体质量普遍减少的后期。
We perform streaming-instability simulations at Hill density and beyond to demonstrate that planetesimal formation is not completed when pebble accumulations exceed the local Hill density. We find that Hill density is not a sufficient criterion for further gravitational collapse of a pebble cloud into a planetesimal, but that additionally the accumulated mass has to be large enough to overcome turbulent diffusion. A Toomre analysis of the system indicates that linear self-gravity modes play no role on the scale of our numerical simulation. We nevertheless find that self-gravity, by vertically contracting the pebble layer, increases the strength of turbulence, which is either an indication of Kelvin–Helmholtz instability or a boost of the streaming instability. We furthermore determine the Bonnor–Ebert central density to which a pebble cloud of a given mass has to be compressed before it would be able to continue contraction against internal diffusion. As the equivalent “solid body” size of the pebble cloud scales with the central density to the power of −1/6, it is much easier to have a pebble cloud of 100 km equivalent size to collapse than one of 10 km for the same level of turbulent diffusion. This can explain the lack of small bodies in the solar system and predicts small objects will form at large pebble-to-gas ratios, so either in the outskirts of the solar nebula or at late times of generally reduced gas mass.
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DOI：
10.1086/344743
发表时间：
2002-11
期刊：
The Astrophysical Journal
影响因子：
--
作者：
H. Klahr;Peter Bodenheimer UCOLick Observatory;C. Physics;I. F. A. U. Astrophysik;U. Tuebingen;H Germany
通讯作者：
H. Klahr;Peter Bodenheimer UCOLick Observatory;C. Physics;I. F. A. U. Astrophysik;U. Tuebingen;H Germany
影响因子：
3.2
作者：
Y. Nakagawa;M. Sekiya;C. Hayashi
通讯作者：
Y. Nakagawa;M. Sekiya;C. Hayashi
尘埃扩散的修订描述和在原行星盘中产生多个环的新不稳定性
DOI：
10.3847/1538-4357/ab25ea
发表时间：
2019
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Tominaga Ryosuke T.;Takahashi Sanemichi Z.;Inutsuka Shu-ichiro
通讯作者：
Inutsuka Shu-ichiro
影响因子：
6.5
作者：
Bethune, William;Lesur, Geoffroy;Ferreira, Jonathan
通讯作者：
Ferreira, Jonathan