标题： 巨行星在行星迁移期间捕获特洛伊小行星 显示英文标题

标题： The Capture of Trojan Asteroids by the Giant Planets During Planetary Migration

摘要： 在太阳系的四颗巨行星中，只有木星和海王星目前已被确认拥有特洛伊小行星群——这些是与宿主行星经历1:1平均运动共振的小天体。 在Lykawka等人（2009年）的研究中，我们进行了广泛的动态模拟，包括行星迁移，以研究海王星特洛伊种群的起源。 利用为该工作获得的大量模拟数据，以及来自新模拟的最新结果，我们在此研究了所有四颗巨行星从原始柯伊伯带盘中动态捕获特洛伊小行星的情况。 我们发现，该区域的一个小行星被捕获到木星特洛伊云轨道上的可能性在几倍于10^-6到10^-5之间。 对于土星，概率范围为小于10^-6到10^-5，而对于天王星，概率范围在10^-5到10^-4之间。 最后，海王星表现出最高的特洛伊捕获概率，数值在10^-4到10^-3之间。 我们的结果表明，到行星迁移结束时，所有四颗巨行星都能够捕获并保留来自盘中的显著特洛伊物体群体。 由于在特洛伊捕获之前与巨行星的相互作用，这些物体倾向于被捕获到轨道偏心率和倾角范围较广的轨道上。 被捕获物体的大部分在某种程度上是动力不稳定的，因此这些物体的群体倾向于随着太阳系的年龄增长而衰减，从而为巨行星之间动态不稳定轨道上的新物体提供了一个重要的持续来源。 考虑到海王星向外迁移会位移大量的物体（潜在的总质量是地球质量的数倍），我们得出结论，在外行星迁移期间被捕获的特洛伊小行星的现存残余可能足以解释目前已知的外太阳系特洛伊小行星群体。 显示英文摘要

摘要： Of the four giant planets in the Solar system, only Jupiter and Neptune are currently known to possess swarms of Trojan asteroids - small objects that experience a 1:1 mean motion resonance with their host planet. In Lykawka et al. (2009), we performed extensive dynamical simulations, including planetary migration, to investigate the origin of the Neptunian Trojan population. Utilising the vast amount of simulation data obtained for that work, together with fresh results from new simulations, we here investigate the dynamical capture of Trojans by all four giant planets from a primordial trans-Neptunian disk. We find the likelihood of a given planetesimal from this region being captured onto an orbit within Jupiter's Trojan cloud lies between several times 10^-6 and 10^-5. For Saturn, the probability is found to be in the range <10^-6 to 10^-5, whilst for Uranus the probabilities range between 10^-5 and 10^-4. Finally, Neptune displays the greatest probability of Trojan capture, with values ranging between 10^-4 and 10^-3. Our results suggest that all four giant planets are able to capture and retain a significant population of Trojan objects from the disk by the end of planetary migration. As a result of encounters with the giant planets prior to Trojan capture, these objects tend to be captured on orbits that are spread over a wide range of orbital eccentricities and inclinations. The bulk of captured objects are to some extent dynamically unstable, and therefore the populations of these objects tend to decay over the age of the Solar System, providing an important ongoing source of new objects moving on dynamically unstable orbits among the giant planets. Given that a huge population of objects would be displaced by Neptune's outward migration (with a potential cumulative mass a number of times that of the Earth), we conclude that the surviving remnant of the Trojans captured during the migration of the outer planets might be sufficient to explain the currently known Trojan populations in the outer Solar system.