论文标题
通过卵石云的重力塌陷对行星形成的高分辨率研究
High Resolution Study of Planetesimal Formation by Gravitational Collapse of Pebble Clouds
论文作者
论文摘要
行星胚胎是通过10-100公里大小的物体的碰撞生长来建立的，称为行星，这是一个以前的大量物体，其中小行星，彗星和kuiper belt物体代表了我们太阳系中星球形成的剩余物体。在这里，我们遵循的范式是，湍流产生了过度密集的卵石云，然后在自己的自我重力下崩溃。我们使用多物理代码GIZMO将卵石云密度建模为连续性，并具有多面性状态方程来说明碰撞的相互作用并捕获相位过渡到准压缩的固体对象，即液压平衡中的行星。因此，我们在形成行星的分辨率下有效地研究了云塌陷，从而使我们能够与塌陷云的总卵石质量相关地得出行星的初始质量功能。折叠卵石云中角动量的重新分布是导致多个碎片化的主要机制。卵石云和离心半径的角动量随着到太阳的距离而增加，但是形成行星的固体尺寸是恒定的。因此，我们发现，随着与太阳的距离增加，每个卵石云的形成行星数量增加。对于所有距离，二进制的形成发生在较高的分层系统内。尺寸分布是顶部重的，可以用行星质量的高斯分布来描述。对于小行星带，我们可以推断出最有可能的125公里的大小，这全部源于等效尺寸152 km的卵石云。
Planetary embryos are built through the collisional growth of 10-100 km sized objects called planetesimals, a formerly large population of objects, of which asteroids, comets and Kuiper-Belt objects represent the leftovers from planet formation in our solar system. Here, we follow the paradigm that turbulence created over-dense pebble clouds, which then collapse under their own self-gravity. We use the multi-physics code GIZMO to model the pebble cloud density as a continuum, with a polytropic equation of state to account for collisional interactions and capturing the phase transition to a quasi-incompressible solid object, i.e. a planetesimal in hydrostatic equilibrium. Thus we study cloud collapse effectively at the resolution of the forming planetesimals, allowing us to derive an initial mass function for planetesimals in relation to the total pebble mass of the collapsing cloud. The redistribution of angular momentum in the collapsing pebble cloud is the main mechanism leading to multiple fragmentation. The angular momentum of the pebble cloud and thus the centrifugal radius increases with distance to the sun, but the solid size of the forming planetesimals is constant. Therefore we find that with increasing distance to the sun, the number of forming planetesimals per pebble cloud increases. For all distances the formation of binaries occurs within higher hierarchical systems. The size distribution is top heavy and can be described with a Gaussian distribution of planetesimal mass. For the asteroid belt, we can infer a most likely size of 125 km, all stemming from pebble clouds of equivalent size 152 km.
