2001 QR322: a dynamically unstable Neptune Trojan?
2001 QR322: a dynamically unstable Neptune Trojan?
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DOI：
10.1111/j.1365-2966.2010.16441.x
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发表时间：
2010-02
影响因子：
4.8
通讯作者：
J. Horner;P. S. Lykawka
中科院分区：
文献类型：
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作者：
J. Horner;P. S. Lykawka
由于早期对第一个海王星特洛伊木马2001 QR 322的稳定性的研究表明，它是一个动态稳定的原始天体，因此人们认为这适用于该天体及其最近发现的兄弟天体。然而，事情似乎不再那么明朗。在这项工作中，我们提出了详细的动力学模拟2001年QR 322的轨道行为的结果。使用星历表的对象，有显着改善，因为早期的作品，我们遵循19 683测试粒子的演变，放置在2001年QR 322的轨道的观测误差椭圆内的轨道上，为1 Gyr的周期。我们发现，大多数2001年QR 322的“克隆”是动态不稳定的，表现出近指数衰减从海王星特洛伊云（衰变半衰期为1.55亿年）和太阳系（衰变半衰期为1.59亿年）。海王星特洛伊云内的天体的稳定性被发现强烈依赖于所使用的初始半长轴，这些位于a≥ 30.30 Au的天体明显不如位于该值内部的天体稳定，这是因为它们的初始天平动振幅非常接近划分规则和不规则运动的临界阈值，位于70°-75°（角运动的全部范围）。这一结果表明，如果2001 QR 322是一个原始的海王星特洛伊，它必须是一个人口的代表，曾经明显大于我们今天看到的，并增加了重量的想法，海王星特洛伊可能是一个重要的来源，物体移动在不稳定的轨道之间的巨行星（半人马座）。
Since early work on the stability of the first Neptunian Trojan, 2001 QR322, suggested that it was a dynamically stable, primordial body, it has been assumed that this applies to both that object and its more recently discovered brethren. However, it seems that things are no longer so clear-cut. In this work, we present the results of detailed dynamical simulations of the orbital behaviour of 2001 QR322. Using an ephemeris for the object that has significantly improved since earlier works, we follow the evolution of 19 683 test particles, placed on orbits within the observational error ellipse of 2001 QR322's orbit, for a period of 1 Gyr. We find that majority of these 'clones' of 2001 QR322 are dynamically unstable, exhibiting a near-exponential decay from both the Neptunian Trojan cloud (decay half-life of ∼550 Myr) and the Solar system (decay half-life of ∼590 Myr). The stability of the object within Neptune's Trojan cloud is found to be strongly dependent on the initial semimajor axis used, with these objects located at a≥ 30.30 au being significantly less stable than those interior to this value, as a result of their having initial libration amplitudes very close to a critical threshold dividing regular and irregular motion, located at ∼70°–75° (full extent of angular motion). This result suggests that if 2001 QR322 is a primordial Neptunian Trojan, it must be a representative of a population that was once significantly larger than that we see today and adds weight to the idea that the Neptune Trojans may represent a significant source of objects moving on unstable orbits between the giant planets (the Centaurs).