Orbital Evolution of Planetesimals due to the Galactic Tide: Formation of the Comet Cloud

Orbital Evolution of Planetesimals due to the Galactic Tide: Formation of the Comet Cloud
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DOI：
10.1086/521815
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发表时间：
2007-08
期刊：
The Astronomical Journal
影响因子：
--
通讯作者：
A. Higuchi;E. Kokubo;H. Kinoshita;T. Mukai
A. Higuchi;E. Kokubo;H. Kinoshita;T. Mukai
中科院分区：
其他
文献类型：
--
作者：
A. Higuchi;E. Kokubo;H. Kinoshita;T. Mukai

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我们用解析表达式研究了受银河潮汐扰动的星子的轨道演化。我们考虑来自银盘的潮汐力的垂直分量。银河潮汐会增加或减少近日点，并随机化远日点距离较大的星子的倾角。我们将解析解应用于由星子盘形成奥尔特云的星子的轨道演化。由于银河潮汐的作用，一些角动量较小的星子在偏心率和倾角上表现出明显的逆变化。此外，一些小子显示出近日点的角在ω = 90°或270°附近的振动（Lidov-Kozai机制）。获得近日点距离的星子足以离开行星区域，成为奥尔特云的成员。我们发现，由于银河潮的影响，半长轴≥1000 AU的星子在行星区（≥100 AU）外增加了近日点距离，半长轴≥20000 AU的星子在5 Gyr内将其倾角扩展到银河面（银河倾角）0°-90°范围内。我们还考虑了致密星系环境对奥尔特云形成的影响，并讨论了具有不同星系倾角的其他行星系统的彗星云。
We have investigated the orbital evolution of planetesimals perturbed by the Galactic tide using analytical expressions. We consider the vertical component of the tidal force from the Galactic disk. The Galactic tide increases or decreases the perihelia and randomizes the inclination of planetesimals with large aphelion distances. We applied the analytical solutions to the orbital evolution of planetesimals that form the Oort Cloud from the planetesimal disk. Due to the Galactic tide, some planetesimals with small angular momentum show substantial inverse variations of the eccentricity and inclination. Also, some planetesimals show libration of the argument of perihelion ω around ω = 90° or 270° (the Lidov-Kozai mechanism). The planetesimals that gain perihelion distances great enough to leave the planetary region become members of the Oort Cloud. We find that due to the Galactic tide, planetesimals with semimajor axes ≳1000 AU increase their perihelion distances outside the planetary region (≳100 AU), and planetesimals with semimajor axes ≳20,000 AU spread their inclinations to the Galactic plane (the Galactic inclinations) over the range 0°-90° in 5 Gyr. We also consider the effect of a dense Galactic environment on the Oort Cloud formation and discuss the comet clouds for other planetary systems with different Galactic inclinations.