论文标题
潮汐锁定身体的动态重新定位:应用于冥王星
Dynamic reorientation of tidally locked bodies: application to Pluto
论文作者
论文摘要
由于与各种类型的内部和外部过程相关的质量重新分布,行星和卫星在空间中的重新定向。虽然对潮汐锁定的身体的平衡取向有充分的理解,但探索的探索少于重新定位过程的动力学(或True Polar Wander,TPW,此处用于旋转或潮汐极的运动)。尽管它们对于预测TPW诱导的表面骨折的模式以及评估是否已经过去了以达到平衡方向的时间来预测其重要性。 Hu等人的一系列论文中描述了唯一的现有且相对复杂的数值方法,用于准确评估潮汐锁定体的重新定向动力学。 (2017a,b,2019年)。在这里,我们证明可以通过简单的方法获得相同的解决方案,称为OW || MMIA,因为与先前的主张相反,在TPW期间,潮汐轴和旋转轴分别遵循了总时间变化的惯性惯性量。由冥王星推测的重新定位的动机,在几个测试示例中说明了OW || MMIA方法的使用。特别是,我们分析重新定向路径是弯曲还是直时,当宿主体的负载符号和质量变化时。当潮汐强迫相对较小时,负异常(例如盆地)朝旋转极的路径高度弯曲,而正载荷可能直接以直接的方式到达子或反宿主点。我们的结果表明,当今的爆发盆地盆地不可能是负异常,并且冥王星的残余图必须在重新定位之前形成。最后,提出的方法与可用于测试数值解决方案的能量平衡相辅相成。
Planets and moons reorient in space due to mass redistribution associated with various types of internal and external processes. While the equilibrium orientation of a tidally locked body is well understood, much less explored are the dynamics of the reorientation process (or true polar wander, TPW, used here for the motion of either the rotation or the tidal pole). This is despite their importance for predicting the patterns of TPW-induced surface fractures, and for assessing whether enough time has passed for the equilibrium orientation to be reached. The only existing, and relatively complex numerical method for an accurate evaluation of the reorientation dynamics of a tidally locked body was described in a series of papers by Hu et al. (2017a,b, 2019). Here we demonstrate that an identical solution can be obtained with a simple approach, denoted as ow||mMIA, because, contrary to previous claims, during TPW the tidal and the rotation axes closely follow respectively the minor and the major axes of the total, time-evolving inertia tensor. Motivated by the presumed reorientation of Pluto, the use of the ow||mMIA method is illustrated on several test examples. In particular, we analyze whether reorientation paths are curved or straight when the load sign and the mass of the host body are varied. When tidal forcing is relatively small, the paths of negative anomalies (e.g.~basins) towards the rotation pole are highly curved, while positive loads may reach the sub- or anti-host point in a straightforward manner. Our results suggest that the Sputnik Planitia basin cannot be a negative anomaly at present day, and that the remnant figure of Pluto must have formed prior to the reorientation. Finally, the presented method is complemented with an energy balance that can be used to test the numerical solution.