Planetesimals to protoplanets - II. Effect of debris on terrestrial planet formation
Planetesimals to protoplanets - II. Effect of debris on terrestrial planet formation
复制标题
星子到原行星 - II。
DOI：
10.1111/j.1365-2966.2009.14769.x
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发表时间：
2009
影响因子：
4.8
通讯作者：
Leinhardt Z
中科院分区：
文献类型：
--
作者：
Leinhardt Z
在本文中，我们扩展了我们的数值模拟类地行星形成的方法，包括未解决的碎片组件的动态摩擦。在以前的工作中，我们实现了碎石堆星子碰撞模型到类地行星形成的直接N体模拟。新的碰撞模型处理了微行星的吸积和侵蚀，但不包括小于模拟分辨率极限的碎片颗粒的动力摩擦。通过扩展我们的数值模型，使之包括未解决的碎片的动力摩擦，我们可以模拟碰撞过程中产生的碎片的动力效应，还可以研究初始碎片质量对类地行星形成的影响。我们发现，显着的初始碎片质量，10%或以上的总光盘质量，改变了微行星的增长模式。具体来说，在这种情况下，星子不会经历失控的增长阶段。相反，它们同时增长，类似于寡头增长。未解决的碎片产生的动力学摩擦阻尼了微行星的偏心率，降低了平均碰撞速度，并导致所有碰撞都导致合并而没有质量损失。因此，没有产生碎片。碎片中的质量随时间缓慢减少。除了包括未解决的碎片的动力学摩擦，我们已经实施了粒子跟踪作为监测成分混合的代理。虽然当包含背景碎片的动力学摩擦时，碰撞和引力散射造成的混合要少得多，但在最极端的初始条件下（未解析碎片的初始质量至少等于解析星子的质量），最大的原行星会显著向内迁移。
In this paper, we extend our numerical method for simulating terrestrial planet formation to include dynamical friction from the unresolved debris component. In the previous work, we implemented a rubble pile planetesimal collision model into directN-body simulations of terrestrial planet formation. The new collision model treated both accretion and erosion of planetesimals but did not include dynamical friction from debris particles smaller than the resolution limit for the simulation. By extending our numerical model to include dynamical friction from the unresolved debris, we can simulate the dynamical effect of debris produced during collisions and can also investigate the effect of initial debris mass on terrestrial planet formation. We find that significant initial debris mass, 10 per cent or more of the total disc mass, changes the mode of planetesimal growth. Specifically, planetesimals in this situation do not go through a runaway growth phase. Instead, they grow concurrently, similar to oligarchic growth. The dynamical friction from the unresolved debris damps the eccentricities of the planetesimals, reducing the mean impact speeds and causing all collisions to result in merging with no mass loss. As a result, there is no debris production. The mass in debris slowly decreases with time. In addition to including the dynamical friction from the unresolved debris, we have implemented particle tracking as a proxy for monitoring compositional mixing. Although there is much less mixing due to collisions and gravitational scattering when dynamical friction of the background debris is included, there is significant inward migration of the largest protoplanets in the most extreme initial conditions (for which the initial mass in unresolved debris is at least equal to the mass in resolved planetesimals).