Catching drifting pebbles
Catching drifting pebbles
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DOI：
10.1051/0004-6361/201732307
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发表时间：
2018-03
影响因子：
6.5
通讯作者：
Beibei Liu;C. Ormel
中科院分区：
文献类型：
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作者：
Beibei Liu;C. Ormel
湍流在卵石大小的颗粒的输送中起着关键作用。它也影响了卵石被原行星吸积的能力，因为它将卵石搅动出圆盘的中平面。此外，一旦相对速度变得太高，沉降机制就不可行，湍流就会抑制卵石的堆积。在论文I之后，我们的目标是通过使用三体模拟计算卵石吸积效率ε来量化这些影响。为了模拟湍流对卵石的影响，我们推导出一个适用于分层磁盘配置的随机运动方程（SEOM）。在强耦合极限下（忽略粒子惯性），该方程的极限形式与前人的工作一致。我们进行了参数研究，并计算了3D中的ε，改变了卵石和气体湍流特性，并考虑了行星倾角。我们发现，强湍流抑制卵石吸积通过湍流扩散，同意密切与以前的工作。当湍流均方根运动很高且沉降机制失效时，ε也会减小。在效率方面，外部盘区域比内部区域更受湍流的影响。在H2O冰线的位置，低质量恒星周围的行星实现了更高的效率。包括文献I的结果，我们给出了一个在一般情况下获得ε的框架。
Turbulence plays a key role in the transport of pebble-sized particles. It also affects the ability of pebbles to be accreted by protoplanets because it stirs pebbles out of the disk midplane. In addition, turbulence suppresses pebble accretion once the relative velocities become too high for the settling mechanism to be viable. Following Paper I, we aim to quantify these effects by calculating the pebble accretion efficiency ε using three-body simulations. To model the effect of turbulence on the pebbles, we derive a stochastic equation of motion (SEOM) applicable to stratified disk configurations. In the strong coupling limit (ignoring particle inertia) the limiting form of this equation agrees with previous works. We conduct a parameter study and calculate ε in 3D, varying pebble and gas turbulence properties and accounting for the planet inclination. We find that strong turbulence suppresses pebble accretion through turbulent diffusion, agreeing closely with previous works. Another reduction of ε occurs when the turbulent rms motions are high and the settling mechanism fails. In terms of efficiency, the outer disk regions are more affected by turbulence than the inner regions. At the location of the H2O iceline, planets around low-mass stars achieve much higher efficiencies. Including the results from Paper I, we present a framework to obtain ε under general circumstances.