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arXiv 1003.0386astro-ph.EP
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水星的核幔相互作用

Core-mantle interactions for Mercury

B. Noyelles, J. Dufey, A. Lemaitre

摘要:

水星是两个空间飞行任务的目标:信使号(美国航天局)计划于2011年3月进入轨道,欧空局/日本宇宙航空研究开发机构BepiColombo应于2014年发射。他们的仪器将以高精度(BepiColombo约为1弧秒)观察行星的表面,这是研究其旋转的动机。水星被认为是由一个坚硬的地幔和一个至少部分熔融的核心组成。在这里,我们研究的影响,核幔相互作用的旋转扰动的太阳引力相互作用,通过模拟的核心作为一个椭圆形的空腔充满了恒定的均匀密度和涡度的无粘流体。我们使用分析(李变换)和数值工具来研究这种旋转,不同形状的核心。我们特别表达了系统的固有频率,因为它们表征了水星对不同请求的响应,这是由于水星围绕太阳的轨道运动。我们表明,相反,它的大小,核心的形状不能确定从观测的纵向或极运动。然而,我们强调了核心的适当频率和水星的自旋之间的共振的强烈影响,提高了核心内的速度场。我们发现,关键参数是极核的扁平。这种效应不能直接从水星表面的观测中得出,但我们不能排除通过测量磁场间接探测的可能性。

英文摘要:

Mercury is the target of two space missions: MESSENGER (NASA) which orbit insertion is planned for March 2011, and ESA/JAXA BepiColombo, that should be launched in 2014. Their instruments will observe the surface of the planet with a high accuracy (about 1 arcsec for BepiColombo), what motivates studying its rotation. Mercury is assumed to be composed of a rigid mantle and an at least partially molten core. We here study the influence of the core-mantle interactions on the rotation perturbed by the solar gravitational interaction, by modeling the core as an ellipsoidal cavity filled with inviscid fluid of constant uniform density and vorticity. We use both analytical (Lie transforms) and numerical tools to study this rotation, with different shapes of the core. We express in particular the proper frequencies of the system, because they characterize the response of Mercury to the different solicitations, due to the orbital motion of Mercury around the Sun. We show that, contrary to its size, the shape of the core cannot be determined from observations of either longitudinal or polar motions. However, we highlight the strong influence of a resonance between the proper frequency of the core and the spin of Mercury that raises the velocity field inside the core. We show that the key parameter is the polar flattening of the core. This effect cannot be directly derived from observations of the surface of Mercury, but we cannot exclude the possibility of an indirect detection by measuring the magnetic field.

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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