论文标题
在巨型时间尺度上的Exceladus上反复的冲击驱动羽流形成
Repeated Impact-Driven Plume Formation On Enceladus Over Megayear Timescales
论文作者
论文摘要
据认为，土豆南极的“老虎条纹”特征爆发的水羽被认为连接到全球地下海洋。形成“老虎条纹”所必需的初始应力的拟议起源包括巨大的冲击，如果不发生冲击在南极发生，则需要真正的极性徘徊来解释羽毛的位置，或者需要与亚地下海洋的部分冷冻相关的拉力膨胀应力。除了需要微调的冲击，真正的极地徘徊或局部冻结地下海洋外，这些假设的另一个问题是，“老虎条纹”可能是短暂的。我们在这里表明，重新铺面可以密封羽毛，质量损失可以导致其压缩和闭合$ \ sim 1 \ mathrm {\; myr} $。由于目前观察到羽毛，因此每$ \ sim 1 \ mathrm {\; myr} $都可以生成新李子的机制，并且最有可能在南极最有可能形成这种李子。我们提出并调查影响的可能性构成了不断裂缝和羽毛的足够重复来源。我们发现，对土豆的影响速率表明，$ \ sim 10^3 $独立的羽流系统每gyr，这是南极的绝大多数，并且与南极的卡西尼衍生时代一致，以实现月球般的轰炸历史，我们对分裂寿命的估计以及所需的参数估计，以及所需的参数。该模型有利于与特里顿（Triton）相似的轰炸历史，而与加利利卫星的轰炸历史相似。
Water plumes erupting from the `tiger stripe' features on the south pole of Enceladus are thought to connect to a global subsurface ocean. Proposed origins for the initial stress necessary to form the `tiger stripes' include a giant impact, which would require true polar wander to explain the location of the plumes if the impact did not occur at the South Pole, or tensile stresses, which would require volumetric expansion associated with partial freezing of the subsurface ocean. In addition to the requirement of a fine-tuned impact, true polar wander, or partial freezing of the subsurface ocean, a further issue with these hypotheses is that the `tiger stripes' may be short-lived. We show here that impact resurfacing can seal off plumes and mass loss can lead to their compression and closure over $\sim 1 \mathrm{\;Myr}$. Since plumes are observed at present, a mechanism by which new plumes can be generated every $\sim 1 \mathrm{\;Myr}$ and by which such plumes are most likely to form at the south pole is needed. We propose and investigate the possibility that impacts constitute an adequate repeating source for the continual instigation of fractures and plumes. We find that the rate of impacts on Enceladus suggests the formation of $\sim 10^3$ independent plume systems per Gyr, the vast majority on the south pole, and is consistent with the Cassini-derived age of the south pole for a lunar-like bombardment history, our estimates of fracture lifetimes, and with the needed parameters for parallel fracture propagation. The model favors a bombardment history similar to that of Triton over one more similar to that of the Galilean satellites.
