High-Resolution Simulations of a Moon-forming Impact and Postimpact Evolution
High-Resolution Simulations of a Moon-forming Impact and Postimpact Evolution
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月球形成撞击和撞击后演化的高分辨率模拟
DOI：
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发表时间：
2006
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通讯作者：
J. Makino
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作者：
K. Wada;E. Kokubo;J. Makino
为了检验月球形成的“巨大撞击假说”，我们对原地球和原行星之间的撞击进行了第一次基于网格的高分辨率流体动力学模拟。与以往基于粒子的模拟相比，碰撞产生的磁盘的空间分辨率得到了极大的提高。这使我们能够探索环绕地球的碎片盘的精细结构及其长期演变。我们发现，为了形成一个碎片盘，使月球大小的卫星能够积聚起来，撞击必须在积聚过程开始之前形成一个主要由液体或固体碎片组成的碎片盘，在那里压力不起作用。如果碎片主要是蒸汽气体，就会产生强烈的螺旋冲击，因此环绕地球的圆盘不能存活超过几天。这表明，由于巨大的撞击，类地行星可能有一个合适的质量范围，因为撞击期间的蒸发取决于撞击能量。
In order to examine the "giant impact hypothesis" for the formation of the Moon, we run the first grid-based, high-resolution hydrodynamic simulations of an impact between proto-Earth and a protoplanet. The spatial resolution for the impact-generated disk is greatly improved from previous particle-based simulations. This allows us to explore the fine structures of a circumterrestrial debris disk and its long-term evolution. We find that in order to form a debris disk from which a lunar-sized satellite can be accumulated, the impact must result in a disk of mostly liquid or solid debris, where pressure is not effective, well before the accumulation process starts. If the debris is dominated by vapor gas, strong spiral shocks are generated, and therefore the circumterrestrial disk cannot survive more than several days. This suggests that there could be an appropriate mass range for terrestrial planets to harbor a large moon as a result of giant impacts, since vaporization during an impact depends on the impact energy.