Repeated Impact-Driven Plume Formation On Enceladus Over Million Year Timescales
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, or tensile stresses, which would require a 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 ∼1Myr. Since plumes are observed at present, a mechanism by which new plumes can be generated every ∼1Myr 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 a adequate repeating source for the continual instigation of fractures and plumes.
We find that the rate of impacts on Enceladus suggests the formation of ∼103 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, and favors a cumulative power-law index of 4.2 for impactors with radius, 1km
Comments: 5 pages, 4 figures; submitted to ApJL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2003.07866 [astro-ph.EP] (or arXiv:2003.07866v1 [astro-ph.EP] for this version)
Submission history
From: Amir Siraj
[v1] Tue, 17 Mar 2020 18:00:03 UTC (143 KB)
https://arxiv.org/abs/2003.07866
Astrobiology
