JUMPING NEPTUNE CAN EXPLAIN THE KUIPER BELT KERNEL
JUMPING NEPTUNE CAN EXPLAIN THE KUIPER BELT KERNEL
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DOI：
10.1088/0004-6256/150/3/68
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发表时间：
2015-09-01
影响因子：
5.3
通讯作者：
Nesvorny, David
中科院分区：
文献类型：
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作者：
Nesvorny, David
柯伊伯带是海王星轨道之外的一群冰冷天体。柯伊伯带的一个特别令人困惑且至今无法解释的特征是所谓的“内核”，即半长轴a近似或等于44 Au、偏心率e近似0.05、倾角i < 5度的轨道集中。在这里，我们表明，柯伊伯带内核可以解释，如果海王星的顺利迁移被中断的不连续变化的海王星的半长轴时，海王星达到类似或等于28 Au。在不连续发生之前，大约40个Au的星子被扫入海王星的2：1共振，并随着共振向外迁移。当海王星达到接近或等于28 Au时，2：1共振在接近或等于44 Au。如果海王星的半长轴在此时改变了Au的几分之一，也许是因为海王星被分散到另一颗行星上，那么2：1的人口将被释放到接近或等于44 Au，并将保持到今天。我们表明，在这个模型中产生的机构的轨道分布提供了一个很好的匹配的内核的轨道特性。如果海王星在跳跃后的迁移速度很慢，那么2：1的共振将耗尽45-47 Au的天体数量，从而导致该区域低倾角轨道的缺乏。仍然需要特别的规定，可能与相当大的物体的吸积生长效率低下有关，以解释为什么到目前为止，只有少数几个低倾角的机构被发现超过类似或等于47 Au。
The Kuiper Belt is a population of icy bodies beyond the orbit of Neptune. A particularly puzzling and up-to-now unexplained feature of the Kuiper Belt is the so-called "kernel," a concentration of orbits with semimajor axes a similar or equal to 44 AU, eccentricities e similar to 0.05, and inclinations i < 5 degrees. Here we show that the Kuiper Belt kernel can be explained if Neptune's otherwise smooth migration was interrupted by a discontinuous change of Neptune's semimajor axis when Neptune reached similar or equal to 28 AU. Before the discontinuity happened, planetesimals located at similar to 40 AU were swept into Neptune's 2:1 resonance, and were carried with the migrating resonance outwards. The 2:1 resonance was at similar or equal to 44 AU when Neptune reached similar or equal to 28 AU. If Neptune's semimajor axis changed by fraction of AU at this point, perhaps because Neptune was scattered off of another planet, the 2:1 population would have been released at similar or equal to 44 AU, and would remain there to this day. We show that the orbital distribution of bodies produced in this model provides a good match to the orbital properties of the kernel. If Neptune migration was conveniently slow after the jump, the sweeping 2:1 resonance would deplete the population of bodies at similar or equal to 45-47 AU, thus contributing to the paucity of the low-inclination orbits in this region. Special provisions, probably related to inefficiencies in the accretional growth of sizable objects, are still needed to explain why only a few low-inclination bodies have been so far detected beyond similar or equal to 47 AU.