Neptune trojan formation during planetary instability and migration
Neptune trojan formation during planetary instability and migration
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DOI：
10.1051/0004-6361/201527757
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发表时间：
2016-08
影响因子：
6.5
通讯作者：
R. Gomes;D. Nesvorný
中科院分区：
文献类型：
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作者：
R. Gomes;D. Nesvorný
目标。本文基于行星不稳定性迁移模型，研究了海王星特洛伊捕获的过程和共振持续到现在的情况。方法.我们对巨行星在小行星盘中的迁移进行了数值模拟。几个星子被困在与海王星的共轨共振中，但没有特洛伊幸存下来，直到4.5戈伊的整合结束。我们增加了统计数据，通过运行合成集成与克隆粒子从原来的整合，并保持相同的迁移率的行星。结果对于合成集成，海王星特洛伊人存活到模拟结束。这些幸存的特洛伊小行星的总质量约为1.6 × 10 - 4地球质量，偏心率、倾角和天平动振幅的分布分别为0.007−0.173、4.9°−32.9°和6.9°−64.3°。当海王星与天王星的平均运动比达到1.963后又下降到现在的1.961时，更多的特洛伊脱离了与海王星的共轨共振，最终形成了质量相当于5 × 10 - 5地球质量的海王星特洛伊。结论.模拟产生的海王星特洛伊木马与真实的海王星特洛伊木马的轨道分布非常匹配。由于不稳定模型中的行星迁移表明，过去海王星可能比现在离太阳更远，因此考虑这种可能性来解释海王星特洛伊相对较低的质量是合理的。
Aims. We investigate the process of Neptune trojan capture and permanence in resonance up to the present time based on a planetary instability migration model. Methods. We do a numerical simulation of the migration of the giant planets in a planetesimal disk. Several planetesimals became trapped in coorbital resonance with Neptune, but no trojan survived to the end of the integration at 4.5 Gy. We increased the statistics by running synthetic integrations with cloned particles from the original integration and keeping the same migration rates of the planets. Results. For the synthetic integrations, Neptune trojans survived to the end of the simulations. The total mass that corresponds to these surviving trojans is about 1.6 × 10 -4 Earth mass and the distributions of eccentricities, inclinations, and libration amplitudes are respectively 0.007−0.173, 4.9°−32.9°, and 6.9°−64.3°. In a specific run where Neptune to Uranus mean motion ratio reached 1.963 and decreased to its present value (1.961), many more trojans escaped the coorbital resonance with Neptune and in the end there was an equivalent mass of 5 × 10 -5 Earth mass of Neptune trojans. Conclusions. The simulations yielded Neptune trojans that match the orbital distribution of real Neptune trojans quite well. Since planetary migration in an instability model shows the possibility that in the past Neptune was a little farther from the Sun than it is today, it is reasonable to consider this possibility to explain the relatively low mass of Neptune trojans.