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arXiv 0911.1369astro-ph.EP
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三体捕获不规则卫星:对木星的应用

Three-Body Capture of Irregular Satellites: Application to Jupiter

Catherine Philpott, Douglas P. Hamilton, Craig B. Agnor

摘要:

我们研究了巨行星不规则卫星起源的新理论:潮汐破坏后捕获了一颗~100公里长的联星小行星的一个成员。破裂所损失的能量足以捕获,但它不能将物体直接送到不规则卫星的观测轨道。相反,长寿的捕获轨道随后由于与稀薄的环行星气体盘的相互作用而向内演化。我们专注于木星的捕获,由于其巨大的质量,为我们的模型提供了最严格的测试。我们研究了被破坏的物体的可能命运,逆行和逆行捕获之间的差异,以及木卫四对捕获物体的影响。我们做了一个脉冲近似,并讨论它如何使我们能够概括捕获结果从等质量的二进制的任意质量比。我们发现,在木星,双星提供了一个因素的增加~10倍的捕获率为100公里的物体相比,单一的机构,由几十个半径的物体,接近地球的相对低能量的轨迹。这些天体有与木卫四相撞的危险,但如果它们的近心点上升得足够快,它们可能会被气体拖曳而保存下来。我们的结论是,我们的机制是能够生产大型不规则的卫星作为以前的建议,它避免了几个问题所面临的替代模型。

英文摘要:

We investigate a new theory of the origin of the irregular satellites of the giant planets: capture of one member of a ~100-km binary asteroid after tidal disruption. The energy loss from disruption is sufficient for capture, but it cannot deliver the bodies directly to the observed orbits of the irregular satellites. Instead, the long-lived capture orbits subsequently evolve inward due to interactions with a tenuous circumplanetary gas disk. We focus on the capture by Jupiter, which, due to its large mass, provides the most stringent test of our model. We investigate the possible fates of disrupted bodies, the differences between prograde and retrograde captures, and the effects of Callisto on captured objects. We make an impulse approximation and discuss how it allows us to generalize capture results from equal-mass binaries to binaries with arbitrary mass ratios. We find that at Jupiter, binaries offer an increase of a factor of ~10 in the capture rate of 100-km objects as compared to single bodies, for objects separated by tens of radii that approach the planet on relatively low-energy trajectories. These bodies are at risk of collision with Callisto, but may be preserved by gas drag if their pericenters are raised quickly enough. We conclude that our mechanism is as capable of producing large irregular satellites as previous suggestions, and it avoids several problems faced by alternative models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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