DIRECT EVIDENCE FOR GRAVITATIONAL INSTABILITY AND MOONLET FORMATION IN SATURN's RINGS
DIRECT EVIDENCE FOR GRAVITATIONAL INSTABILITY AND MOONLET FORMATION IN SATURN's RINGS
复制标题
DOI：
10.1088/2041-8205/718/2/l176
复制
发表时间：
2010-08-01
影响因子：
7.9
通讯作者：
Agnor, C. B.
中科院分区：
文献类型：
--
作者：
Beurle, K.;Murray, C. D.;Agnor, C. B.
来自卡西尼号宇宙飞船的新图像揭示了土星F环区域的光学厚团块，能够投射阴影，以及相关结构，这些区域最近经历了相邻卫星普罗米修斯的近距离通过。利用这些图像和模型，我们表明普罗米修斯的扰动产生了密度增强和相对速度较低的区域，这些区域容易受到引力不稳定的影响，并形成膨胀的，但长期存在的，引力相干的团块。这些低密度团块随后的碰撞阻尼可能促进它们坍缩成类似于10-20公里连续的小卫星。观察到的F环的行为类似于一个边缘稳定的气体盘在嵌入气体巨行星的扰动下被驱动到不稳定和坍缩的情况。
New images from the Cassini spacecraft reveal optically thick clumps, capable of casting shadows, and associated structures in regions of Saturn's F ring that have recently experienced close passage by the adjacent moon Prometheus. Using these images and modeling, we show that Prometheus' perturbations create regions of enhanced density and low relative velocity that are susceptible to gravitational instability and the formation of distended, yet long-lived, gravitationally coherent clumps. Subsequent collisional damping of these low-density clumps may facilitate their collapse into similar to 10-20 km contiguous moonlets. The observed behavior of the F ring is analogous to the case of a marginally stable gas disk being driven to instability and collapse via perturbations from an embedded gas giant planet.