Shapes of the saturnian icy satellites and their significance
Shapes of the saturnian icy satellites and their significance
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DOI：
10.1016/j.icarus.2007.03.012
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发表时间：
2007-10
期刊：
影响因子：
3.2
通讯作者：
P. Thomas;J. Burns;P. Helfenstein;S. Squyres;J. Veverka;C. Porco;E. Turtle;A. McEwen;T. Denk;B. Giese;T. Roatsch;T. Johnson;R. Jacobson
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文献类型：
--
作者：
P. Thomas;J. Burns;P. Helfenstein;S. Squyres;J. Veverka;C. Porco;E. Turtle;A. McEwen;T. Denk;B. Giese;T. Roatsch;T. Johnson;R. Jacobson
使用边缘坐标和立体测量控制点，通过卡西尼号成像科学子系统（ISS）数据测量了六颗冰冷土星卫星的大小和形状。土卫一、土卫二、土卫三、土卫四和土卫五可以用三轴椭球体来描述;土卫八最好用扁球体来描述。所有卫星似乎都在其演变过程中的某个时刻接近放松的平衡形状，但所有卫星都支持至少300米的全球波长地形。土卫二的形状与均匀的内部最为一致。如果土卫二是分化的，它的形状和明显的松弛需要在冰冷的地幔和/或不规则形状的核心横向不均匀性。土卫八支持超过30公里的化石隆起，并提供了一个基准的影响修改后的形状全球松弛。像土卫一这样有着比土卫八更光滑的四肢，并且预计会有更高的撞击率的土星，一定是在土卫八的形状被冻结后放松的。
The sizes and shapes of six icy saturnian satellites have been measured from Cassini Imaging Science Subsystem (ISS) data, employing limb coordinates and stereogrammetric control points. Mimas, Enceladus, Tethys, Dione and Rhea are well described by triaxial ellipsoids; Iapetus is best represented by an oblate spheroid. All satellites appear to have approached relaxed, equilibrium shapes at some point in their evolution, but all support at least 300 m of global-wavelength topography. The shape of Enceladus is most consistent with a homogeneous interior. If Enceladus is differentiated, its shape and apparent relaxation require either lateral inhomogeneities in an icy mantle and/or an irregularly shaped core. Iapetus supports a fossil bulge of over 30 km, and provides a benchmark for impact modification of shapes after global relaxation. Satellites such as Mimas that have smoother limbs than Iapetus, and are expected to have higher impact rates, must have relaxed after the shape of Iapetus was frozen.