University of Oulu

Martin Seiß et al 2019 AJ 157 6.

Hydrodynamic simulations of moonlet-induced propellers in Saturn’s rings : application to Blériot

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Author: Seiss, Martin1; Albers, Nicole2; Sremčević, Miodrag2;
Organizations: 1Department of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany
2LASP, University of Colorado, 1234 Innovation Drive, Boulder, USA
3Astronomy Research Unit, University of Oulu, Pentti Kaiteran katu 1, 90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4 MB)
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Language: English
Published: IOP Publishing, 2019
Publish Date: 2019-06-28


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 ν₀ = 340 cm² s⁻¹, a dispersion velocity in the range of 0.3 cm s⁻¹ < c₀ < 1.5 cm s⁻¹, and a fairly high bulk viscosity 7 < ξ₀/ν₀ < 17. These large transport values might be overestimated by our isothermal ring model and should be reviewed by an extended model including thermal fluctuations.

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Series: The astronomical journal
ISSN: 0004-6256
ISSN-E: 1538-3881
ISSN-L: 0004-6256
Volume: 157
Issue: 1
Article number: 6
DOI: 10.3847/1538-3881/aaed44
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work has been supported by the Deutsches Zentrum für Luft-und Raumfahrt (OH 1401), the Deutsche Forschungsgemeinschaft (Sp 384/28-1, Ho5720/1-1), and the Cassini project.
Copyright information: © 2018. The American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.