The Orbital Stability of Planets Trapped in the First-Order Mean-Motion Resonances
The Orbital Stability of Planets Trapped in the First-Order Mean-Motion Resonances
复制标题
陷入一阶平均运动共振的行星的轨道稳定性
DOI：
10.1016/j.icarus.2012.08.032
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发表时间：
2012
期刊：
影响因子：
3.2
通讯作者：
S
中科院分区：
文献类型：
--
作者：
Matsumoto;Y.;Nagasawa;M. & Ida;S
许多太阳系外的行星系统包含多个超级地球已被发现。考虑到标准的I型行星迁移的N体模拟表明，原行星被捕获到靠近内盘边缘的平均运动共振轨道，在那里迁移停止。以前的N体模拟表明，共振系统的轨道稳定性取决于被捕获行星的数量。在不稳定的情况下，通过行星间的紧密散射和合并，最终形成非共振的多重系统。在本文中，我们调查的临界数量的共振捕获行星超过轨道不稳定发生后磁盘气体耗尽。我们发现当行星总数N大于临界数Ncrit时，轨道不稳定性开始的时间尺度--穿越时间与非共振情况相似，而在N <$Ncrit的轨道计算时间（108 Kepler时间）内，轨道不稳定性从未发生.因此，跨越临界数的跨越时间的转变是剧烈的。当所有的行星都被困在7：6的相邻对共振中时，Ncrit=4。通过改变轨道间距和行星质量，研究了4：3，6：5和8：7共振的临界数随轨道间距的变化关系.当行星质量固定时，临界数随希尔半径轨道间距的增加而增加;当希尔半径轨道间距固定时，临界数随行星质量的增加而增加。我们还计算了一个系统的情况下，这不是由相同的共振。开普勒使命揭示了稳定性的急剧转变可能是多个超级地球（非共振或共振）多样性的原因。
Many extrasolar planetary systems containing multiple super-Earths have been discovered. N-body simulations taking into account standard type-I planetary migration suggest that protoplanets are captured into mean-motion resonant orbits near the inner disk edge at which the migration is halted. Previous N-body simulations suggested that orbital stability of the resonant systems depends on number of the captured planets. In the unstable case, through close scattering and merging between planets, non-resonant multiple systems are finally formed. In this paper, we investigate the critical number of the resonantly trapped planets beyond which orbital instability occurs after disk gas depletion. We find that when the total number of planets (N) is larger than the critical number (Ncrit), crossing time that is a timescale of initiation of the orbital instability is similar to non-resonant cases, while the orbital instability never occurs within the orbital calculation time (108Kepler time) for N⩽Ncrit. Thus, the transition of crossing time across the critical number is drastic. When all the planets are trapped in 7:6 resonance of adjacent pairs, Ncrit=4. We examine the dependence of the critical number of 4:3, 6:5 and 8:7 resonance by changing the orbital separation in mutual Hill radii and planetary mass. The critical number increases with increasing the orbital separation in mutual Hill radii with fixed planetary mass and increases with increasing planetary mass with fixed the orbital separation in mutual Hill radii. We also calculate the case of a system which is not composed of the same resonance. The sharp transition of the stability can be responsible for the diversity of multiple super-Earths (non-resonant or resonant), that is being revealed by Kepler Mission.