文章基本信息

标题：Hydrodynamic Simulations of Moonlet-induced Propellers in Saturn’s Rings: Application to Blériot
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作者：Martin Seiß ; Nicole Albers ; Miodrag Sremčević 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2019
卷号：157
期号：1
页码：1-11
DOI：10.3847/1538-3881/aaed44
语种：English
出版社：American Institute of Physics
摘要：One of the biggest successes of the Cassini mission is the detection of small moons (moonlets) embedded in Saturns rings that cause S-shaped density structures in their close vicinity, called propellers. Here, we present isothermal hydrodynamic simulations of moonlet-induced propellers in Saturn’s A ring that denote a further development of the original model. We find excellent agreement between these new hydrodynamic and corresponding N-body simulations. Furthermore, the hydrodynamic simulations confirm the predicted scaling laws and the analytical solution for the density in the propeller gaps. Finally, this mean field approach allows us to simulate the pattern of the giant propeller Blériot, which is too large to be modeled by direct N-body simulations. Our results are compared to two stellar occultation observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS), which intersect the propeller Blériot. Best fits to the UVIS optical depth profiles are achieved for a Hill radius of 590 m, which implies a moonlet diameter of about 860 m. Furthermore, the model favors a kinematic shear viscosity of the surrounding ring material of ν 0 =340cm 2 s −1 , a dispersion velocity in the range of 0.3 cms −1 <c 0 <1.5 cm s −1 , and a fairly high bulk viscosity 7<ξ 0 /ν 0 <17. These large transport values might be overestimated by our isothermal ring model and should be reviewed by an extended model including thermal fluctuations.
关键词：diffusion;hydrodynamics;planets and satellites: rings