Formation of the Terrestrial Planets
Formation of the Terrestrial Planets
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DOI：
10.1146/annurev.aa.18.090180.000453
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发表时间：
1980
影响因子：
33.3
通讯作者：
G. Wetherill
中科院分区：
文献类型：
--
作者：
G. Wetherill
类地行星的形成有两种机制：（1）引力不稳定导致坍缩;（2）两体碰撞和相干导致引力积累。动态显着气相的存在不会影响这两种机制。本文给出了在中心尘埃层内由引力不稳定性产生巨大气态原行星的理论表达式。引力的积累是讨论参考的积累星子从一个无气体的环日天体群。数值模拟的早期阶段的积累。Safronov稳态速度被认为是，注意到相互碰撞阻尼和引力加速度之间的竞争由太阳群的成员产生的稳态速度分布的平均速度是可比的逃逸速度的最大的机构。积累的时间尺度是假定的基础上的径向分布的一群非增生机构的大小相等。注意到几个类地行星同时存在无气体聚集。还关注富含气体的行星际介质中的生长机制。
Two growth mechanisms are identified for the development of the terrestrial planets: (1) gravitational instability leading to a collapse, and (2) gravitational accumulation caused by two-body collisions and coherence. The presence of a dynamically-significant gas phase would not affect either mechanism. Theoretical expressions are presented for the production of giant gaseous protoplanets by gravitational instability within a central dust layer. Gravitational accumulation is discussed with reference to the accumulation of planetesimals from a gas-free circumsolar swarm of bodies. Numerical simulations are given for the early stages of accumulation. The Safronov steady-state velocity is considered, noting that the competition between mutual collisional damping and gravitational acceleration by the members of a solar swarm yields a steady-state velocity distribution where the mean velocity is comparable to the escape velocity of the largest body. A time scale for accumulation is postulated on the basis of the radial distribution of a swarm of non-accreting bodies of equal size. The simultaneous gas-free accumulation of several terrestrial planets is noted. Attention is also given to growth mechanisms in gas-rich interplanetary media.