Dynamical evolution of triple-star systems by Lidov–Kozai cycles and tidal friction
Dynamical evolution of triple-star systems by Lidov–Kozai cycles and tidal friction
复制标题
Lidov-Kozai 循环和潮汐摩擦引起的三星系统动力学演化
DOI：
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发表时间：
2018
影响因子：
4.8
通讯作者：
A. Correia
中科院分区：
文献类型：
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作者：
M. Bataille;Anne;A. Correia
许多三颗星系统都有一对内星，其轨道周期只有几天。解释观测中出现的短周期堆积的一种常见机制是通过Lidov-Kozai旋回与潮汐摩擦相结合的迁移。在这里，我们重新审视这一机制，并旨在确定导致这一过程的初始轨道构型。我们发现，三星系统的相互倾角并不是唯一的关键参数，因为内轨道的偏心率以及中心附近的自变量在建立Lidov-Kozai迁移过程中也起着重要的作用。我们的框架是带有广义相对论修正的长期等级三体问题(八极序近似)，包括潮汐、恒星扁率和磁自旋向下制动的影响。同时考虑了轨道演化和自旋演化。对初始轨道参数的均匀分布和非均匀分布进行了广泛的数值模拟，揭示了导致Lidov-Kozai迁移的无偏初始条件。最后，我们强调了初始“Kozai常数”$h=Sqrt{(1-e^2)}cos{i}$在三星系统动力学演化中的重要性，指出在给定的$h$值下的相图揭示了不同的演化路径。
Many triple-star systems have an inner pair with an orbital period of a few days only. A common mechanism to explain the short-period pile-up present in the observations is the migration through Lidov-Kozai cycles combined with tidal friction. Here, we revisit this mechanism and aim to determine the initial orbital configurations leading to this process. We show that the mutual inclination of the triple-star system is not the only critical parameter, since the eccentricity as well as the argument of the pericenter of the inner orbit also play an important role in the establishment of the Lidov-Kozai migration. Our framework is the secular hierarchical three-body problem (octupole order approximation) with general relativity corrections, including the effects of tides, stellar oblateness and magnetic spin-down braking. Both the orbital and the spin evolutions are considered. Extensive numerical simulations with uniform and non-uniform distributions of the initial orbital parameters are carried out, and unbiased initial conditions leading to Lidov-Kozai migration are revealed. Finally, we highlight the importance of the initial "Kozai constant" $h=sqrt{(1-e^2)}cos{i}$ in the dynamical evolution of triple-star systems, by showing that phase portraits at given $h$-values unveil different evolution paths.