Tilting Saturn. I. Analytic Model
Tilting Saturn. I. Analytic Model
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DOI：
10.1086/424533
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发表时间：
2004-11
期刊：
影响因子：
--
通讯作者：
W. Ward;D. Hamilton
中科院分区：
文献类型：
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作者：
W. Ward;D. Hamilton
土星自转轴与轨道平面的倾角为26.°7，而木星的倾角仅为3.°1。我们提供了一个解释这个令人费解的差异，由于土星的引力摄动行星海王星。土星自转轴的岁差周期与海王星微倾斜轨道面的1.87 × 106年岁差周期之间的相似性暗示了这两颗行星之间的共振相互作用是土星从最初更直立的状态倾斜的原因。我们做了一个案例，土星被捕获到这个共振过程中的柯伊伯带的侵蚀，这降低了海王星的轨道平面的回归率。穿透共振将土星的质量提升到目前的水平。自旋轴也可能在共振中振动，振幅为31°，我们讨论了可能的原因以及对土星惯性矩的隐含约束。将当前的极位置与预测的结果相匹配可能会对早期太阳系的过程产生限制。
The tilt of Saturn's spin axis to its orbit plane is 26.°7, while that of Jupiter is only 3.°1. We offer an explanation for this puzzling difference owing to gravitational perturbations of Saturn by the planet Neptune. A similarity between the precession period of Saturn's spin axis and the 1.87 × 106 yr precession period of Neptune's slightly inclined orbit plane implicates a resonant interaction between these planets as responsible for tilting Saturn from an initially more upright state. We make a case that Saturn was captured into this resonance during the erosion of the Kuiper belt, which decreased the rate of regression of Neptune's orbit plane. Penetrating the resonance pumped up Saturn's obliquity to its current value. The spin axis may also be librating in the resonance with an amplitude ψ ≳ 31°, and we discuss possible causes of this and the implied constraint on Saturn's moment of inertia. Matching the current pole position to the predicted outcome could place constraints on early solar system processes.