Innocent Bystanders: Orbital Dynamics of Exomoons During Planet–Planet Scattering
Innocent Bystanders: Orbital Dynamics of Exomoons During Planet–Planet Scattering
复制标题
无辜的旁观者：行星-行星散射期间系外卫星的轨道动力学
DOI：
10.3847/1538-4357/aaa0db
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
J. Lunine
中科院分区：
文献类型：
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作者：
Yu;S. Raymond;P. Nicholson;J. Lunine
行星-行星散射是解释观测到的巨大系外行星广泛偏心分布的主要机制。在这里，我们研究了在这种情况下原始巨行星卫星的轨道稳定性。我们使用n体模拟，包括真实的扁率和巨大行星的演化自旋演化。我们发现绝大多数（在我们所有的模拟中约80%-90%）卫星的轨道参数空间是不稳定的。有一个强烈的径向依赖，因为卫星过去被系统地移除。在类似伽利略卫星的轨道上（<0.04 RHill）的近距离卫星有很好的（~ 20%-40%）生存机会。不稳定的卫星可能会与恒星或行星发生碰撞，被抛出系统，被另一颗行星捕获，被抛出但仍围绕其自由浮动的主行星运行，或者作为“行星”在日心轨道上存活下来。卫星的存活率随着宿主行星质量的增加而增加，但与行星的最终（散射后）轨道无关。根据我们的模拟，我们预测银河系中存在大量自由漂浮的（前）卫星。
Planet–planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (∼80%–90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past are systematically removed. Closer-in moons on Galilean-moon-like orbits (<0.04 RHill) have a good (∼20%–40%) chance of survival. Destabilized moons may undergo a collision with the star or a planet, be ejected from the system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as “planets.” The survival rate of moons increases with the host planet mass but is independent of the planet’s final (post-scattering) orbits. Based on our simulations, we predict the existence of an abundant galactic population of free-floating (former) moons.