Hydrodynamic Simulations of Asymmetric Propeller Structures in Saturn's Rings
- The observation of the non-Keplerian behavior of propeller structures in Saturn's outer A ring raises the question: how does the propeller respond to the wandering of the central embedded moonlet? Here, we study numerically how the structural imprint of the propeller changes for a libration of the moonlet. It turns out that the libration induces an asymmetry in the propeller, which depends on the libration period and amplitude of the moonlet. Further, we study the dependence of the asymmetry on the libration period and amplitude for a moonlet with a 400 m Hill radius, which is located in the outer A ring. This allows us to apply our findings to the largest known propeller Blériot, which is expected to be of a similar size. For Blériot, we can conclude that, supposing the moonlet is librating with the largest observed period of 11.1 yr and an azimuthal amplitude of about 1845 km, a small asymmetry should be measurable but depends on the moonlet's libration phase at the observation time. The longitude residuals of other trans-EnckeThe observation of the non-Keplerian behavior of propeller structures in Saturn's outer A ring raises the question: how does the propeller respond to the wandering of the central embedded moonlet? Here, we study numerically how the structural imprint of the propeller changes for a libration of the moonlet. It turns out that the libration induces an asymmetry in the propeller, which depends on the libration period and amplitude of the moonlet. Further, we study the dependence of the asymmetry on the libration period and amplitude for a moonlet with a 400 m Hill radius, which is located in the outer A ring. This allows us to apply our findings to the largest known propeller Blériot, which is expected to be of a similar size. For Blériot, we can conclude that, supposing the moonlet is librating with the largest observed period of 11.1 yr and an azimuthal amplitude of about 1845 km, a small asymmetry should be measurable but depends on the moonlet's libration phase at the observation time. The longitude residuals of other trans-Encke propellers (e.g., Earhart) show amplitudes similar to Blériot, which might allow us to observe larger asymmetries due to their smaller azimuthal extent, allowing us to scan the whole gap structure for asymmetries in one observation. Although the librational model of the moonlet is a simplification, our results are a first step toward the development of a consistent model for the description of the formation of asymmetric propellers caused by a freely moving moonlet.…
Author details: | Michael SeilerORCiDGND, Martin SeißORCiDGND, Holger HoffmannORCiDGND, Frank SpahnORCiDGND |
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DOI: | https://doi.org/10.3847/1538-4365/ab26b0 |
ISSN: | 0067-0049 |
ISSN: | 1538-4365 |
Title of parent work (English): | The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series |
Publisher: | IOP Publ. Ltd. |
Place of publishing: | Bristol |
Publication type: | Article |
Language: | English |
Year of first publication: | 2019 |
Publication year: | 2019 |
Release date: | 2020/12/07 |
Tag: | Hydrodynamics; methods: data analysis; methods: numerical; planets and satellites: dynamical evolution and stability; planets and satellites: individual (Saturn); planets and satellites: rings |
Volume: | 243 |
Issue: | 2 |
Number of pages: | 16 |
Funding institution: | Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [Sp 384/28-1, Sp 384/28-2, Ho 5720/1-1]; Deutsches Zentrum fur Luft-und RaumfahrtHelmholtz AssociationGerman Aerospace Centre (DLR) [OH 1401] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
Peer review: | Referiert |
Publishing method: | Open Access / Hybrid Open-Access |