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How Cassini can constrain tidal dissipation in Saturn

Luan, Jing and Fuller, Jim and Quataert, Eliot (2018) How Cassini can constrain tidal dissipation in Saturn. Monthly Notices of the Royal Astronomical Society, 473 (4). pp. 5002-5014. ISSN 0035-8711. doi:10.1093/mnras/stx2714.

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Tidal dissipation inside giant planets is important for the orbital evolution of their natural satellites. It is conventionally treated by parametrized equilibrium tidal theory, in which the tidal torque declines rapidly with distance, and orbital expansion was faster in the past. However, some Saturnian satellites are currently migrating outward faster than predicted by equilibrium tidal theory. Resonance locking between satellites and internal oscillations of Saturn naturally matches the observed migration rates. Here, we show that the resonance locking theory predicts dynamical tidal perturbations to Saturn's gravitational field in addition to those produced by equilibrium tidal bulges. We show that these perturbations can likely be detected during Cassini’s proximal orbits if migration of satellites results from resonant gravity modes, but will likely be undetectable if migration results from inertial wave attractors or dissipation of the equilibrium tide. Additionally, we show that the detection of gravity modes would place constraints on the size of the hypothetical stably stratified region in Saturn.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Luan, Jing0000-0001-6048-1959
Fuller, Jim0000-0002-4544-0750
Quataert, Eliot0000-0001-9185-5044
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 October 16. Received 2017 October 13; in original form 2017 July 8. Published: 23 October 2017. We thank Peter Goldreich for his insightful suggestions and comments. We thank Phillip D. Nicholson and Luciano Iess for providing us information about the proximal orbits of Cassini. We thank Gordon Ogilvie for his clarification about his work on inertial waves, i.e. Ogilvie (2013). We thank Douglas N. C. Lin for his comments on inertial wave attractors. Jing Luan is supported by the Theoretical Astronomy Center and Center for Integrative Planetary Science at University of California at Berkeley. This research is funded in part by the Gordon and Betty Moore Foundation through Grant GBMF5076 and by the Simons Foundation through a Simons Investigator Award to Eliot Quataert.
Group:TAPIR, Walter Burke Institute for Theoretical Physics, Astronomy Department
Funding AgencyGrant Number
University of California, BerkeleyUNSPECIFIED
Gordon and Betty Moore FoundationGBMF5076
Simons FoundationUNSPECIFIED
Subject Keywords:hydrodynamics –waves – planets and satellites: interiors – planets and satellites: physical evolution
Issue or Number:4
Record Number:CaltechAUTHORS:20180222-081503594
Persistent URL:
Official Citation:Jing Luan, Jim Fuller, Eliot Quataert; How Cassini can constrain tidal dissipation in Saturn, Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 4, 1 February 2018, Pages 5002–5014,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84916
Deposited By: Tony Diaz
Deposited On:22 Feb 2018 18:00
Last Modified:15 Nov 2021 20:24

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