在高偏心率迁移情景中围绕热彗星的外卫星的不祥命运
The ominous fate of exomoons around hot Jupiters in the high-eccentricity migration scenario
摘要：
太阳系中所有的巨行星都有大量的天然卫星。太阳系外的卫星很难被探测到，但最近在开普勒-1625b系统的一颗彗星大小的行星周围发现了一颗海王星大小的系外卫星候选者。由于它们相对容易被探测到，热彗星（HJs），它们在围绕其宿主恒星的近轨道上停留了几天，可能是寻找外卫星的非常好的候选者。目前尚不清楚HJ种群是否可以宿主（或可能已经宿主）外卫星。一个建议的形成通道HJs的高偏心率迁移引起的恒星双星伴结合潮汐耗散。在这里，我们调查在何种情况下的exomoon可以防止或允许高偏心率迁移的HJ，在后一种情况下，如果exomoon可以生存的迁移过程。我们使用半解析参数，以及直接N体模拟，包括潮汐相互作用。我们的研究结果表明，大规模的外卫星是有效的，在防止高偏心率迁移。如果一颗系外卫星确实允许行星迁移，那么形成的HJ不太可能容纳系外卫星，因为月球在迁移过程中要么会螺旋到行星上，要么会逃离行星。一些逃脱的系外卫星可以在木星迁移后成为稳定的行星，或者通过潮汐迁移自己。大多数系外卫星最终被抛出系统或与主星和宿主行星相撞。尽管如此，这种碰撞仍可能留下可观察到的特征，例如围绕主星的碎片盘或围绕近距离巨星的驱逐物。
英文摘要：
All the giant planets in the solar system host a large number of natural satellites. Moons in extrasolar systems are difficult to detect, but a Neptune-sized exomoon candidate has been recently found around a Jupiter-sized planet in the Kepler-1625bsystem. Due to their relative ease of detection, hot Jupiters (HJs), which reside in close orbits around their host stars with a period of a few days, may be very good candidates to search for exomoons. It is still unknown whether the HJ population can host (or may have hosted) exomoons. One suggested formation channel for HJs is high-eccentricity migration induced by a stellar binary companion combined with tidal dissipation. Here, we investigate under which circumstances an exomoon can prevent or allow high-eccentricity migration of a HJ, and in the latter case, if the exomoon can survive the migration process. We use both semianalytic arguments, as well as direct N-body simulations including tidal interactions. Our results show that massive exomoons are efficient at preventing high-eccentricity migration. If an exomoon does instead allow for planetary migration, it is unlikely that the HJ formed can host exomoons since the moon will either spiral onto the planet or escape from it during the migration process. A few escaped exomoons can become stable planets after the Jupiter has migrated, or by tidally migrating themselves. The majority of the exomoons end up being ejected from the system or colliding with the primary star and the host planet. Such collisions might nonetheless leave observable features, such as a debris disc around the primary star or exorings around the close-in giant.
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