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巨大衝突に始まる月形成:岩石破片円盤形成から揮発性物質散逸まで

月球的形成始于巨大的撞击：从岩石碎片盘的形成到挥发性物质的消散

基本信息

批准号：
12640405
负责人：
NAKAZAWA Kiyoshi
金额：
$ 2.3万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

The giant impact between a Mars size proto-planet and the Earth could produce the moon. This is the model of moon formation called "The Giant Impact Model". Today many scientists studying about the origin of the moon consider the model the most reliable one. In this study we investigated the model in two parts for two years. First part is study about the giant impact it self. Second is the accumulation process of the moon from the disk around the Earth.The accumulation of the moon in the circum earth disk was supported by strong mass transfer due to the axis-asymmetric gravitational field produced by density waves in the disk. The gravitational field carried the rock debris outer than the Roche limits. Then the debris accumulated to the single moon. We have confirmed the transfer process by N-body numerical simulation and formulate the transfer rate as a function of initial disk mass theoretically. In addition to that, we found that initially light disk could produce multiple moonlets … More outside the Roche limits and initially heavy one could produce massive single moon. So, we estimate the initial disk mass of the Earth which has single moon as heavier than 3 times the mass of the moon.The giant impacts between proto-planets could take place very frequently in the planetary formation process. So, it is important to investigate the impacts not only as the moon formation stage but also one of the important basic process in the planetary formation. We have investigated the giant impact process under the wide range of impact parameters rather than to concentrate on the moon formation process only. From the studies we have found that the proto planet deformed significantly at the impact instance, but the proto planet restore its global figure by its strong self gravity. In addition to that we confirmed that the restored proto planet was on the oval orbit around the Earth which never produces the giant impact any more. This fact implies that the giant impact process could play a role resemble to the "Capture process" in the moon formation. Less

火星大小的原行星与地球之间的巨大撞击可能会产生月球。这是月球形成的模型，称为“巨大撞击模型”。如今，许多研究月球起源的科学家认为该模型是最可靠的模型。在本研究中，我们分两部分对该模型进行了两年的研究。第一部分是对它自身巨大影响的研究。其次是月球从地球圆盘中的聚集过程，月球在地球圆盘中的聚集是由圆盘中密度波产生的非轴对称引力场所引起的强质量转移所支持的。重力场把岩石碎片带到了洛希极限之外。然后碎片堆积到了唯一的月亮上。我们用N体数值模拟证实了转移过程，并从理论上给出了转移率与初始盘质量的函数关系。除此之外，我们发现最初的光盘可以产生多个小卫星 ...更多信息在洛希极限之外，最初很重的一个可以产生巨大的单卫星。因此，我们估算了地球的初始盘质量，其中有一个卫星，其质量大于3倍的月球质量。在行星形成过程中，原行星之间的巨大碰撞可能会频繁发生。因此，对月球撞击的研究不仅是月球形成的重要阶段，而且是行星形成的重要基础过程之一。我们已经研究了大范围的撞击参数下的巨大撞击过程，而不仅仅是集中在月球的形成过程。研究发现，原行星在撞击瞬间发生了明显的形变，但原行星依靠自身强大的引力恢复了原来的整体形状。除此之外，我们还证实了恢复的原行星是在围绕地球的椭圆形轨道上，再也不会产生巨大的影响。这一事实意味着巨大的撞击过程可能在月球形成中起到类似于“捕获过程”的作用。少