Poincaré-Hough卫星在低偏心率下的近同步旋转行为
Behavior of nearby synchronous rotation of a Poincaré-Hough satellite at low eccentricity
摘要：
本文研究了同步天然卫星自转的Poincaré-Hough模型，其中假定这些天体由刚性地幔和三轴空腔组成，空腔中充满恒定均匀密度和涡度的无粘流体。在考虑低偏心率轨道上的类木卫一天体时，我们描述了系统的不同可能行为，这取决于核的大小、极扁率和形状。我们使用数字工具。我们传播数值系统的Hamilton方程，然后表示所得到的变量下的准周期表示。该表达式是通过频率分析数值获得的。这使我们能够描述系统的平衡，并区分其随时间变化的原因。我们表明，即使没有轨道偏心率，系统可以有复杂的行为，特别是当核心是高度扁平。在这种情况下，极移被强迫几度，并出现纵向平动。这是由于极移平衡位置的分裂。当核的极扁率较小时，我们还得到了磁共振强度的变化。
英文摘要：
This paper presents a study of the Poincaré-Hough model of rotation of the synchronous natural satellites, in which these bodies are assumed to be composed of a rigid mantle and a triaxial cavity filled with inviscid fluid of constant uniform density and vorticity. In considering an Io-like body on a low eccentricity orbit, we describe the different possible behaviors of the system, depending on the size, polar flattening and shape of the core. We use for that the numerical tool. We propagate numerically the Hamilton equations of the systems, before expressing the resulting variables under a quasi-periodic representation. This expression is obtained numerically by frequency analysis. This allows us to characterize the equilibria of the system, and to distinguish the causes of their time variations. We show that, even without orbital eccentricity, the system can have complex behaviors, in particular when the core is highly flattened. In such a case, the polar motion is forced by several degrees and longitudinal librations appear. This is due to splitting of the equilibrium position of the polar motion. We also get a shift of the obliquity when the polar flattening of the core is small.
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