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Published June 1, 2016 | Submitted + Published
Journal Article Open

Resonance locking as the source of rapid tidal migration in the Jupiter and Saturn moon systems


The inner moons of Jupiter and Saturn migrate outwards due to tidal energy dissipation within the planets, the details of which remain poorly understood. We demonstrate that resonance locking between moons and internal oscillation modes of the planet can produce rapid tidal migration. Resonance locking arises due to the internal structural evolution of the planet and typically produces an outward migration rate comparable to the age of the Solar system. Resonance locking predicts a similar migration time-scale but a different effective tidal quality factor Q governing the migration of each moon. The theory also predicts nearly constant migration time-scales a function of semimajor axis, such that effective Q values were larger in the past. Recent measurements of Jupiter and Saturn's moon systems find effective Q values that are smaller than expected (and are different between moons), and which correspond to migration time-scales of ∼10 Gyr. If confirmed, the measurements are broadly consistent with resonance locking as the dominant source of tidal dissipation in Jupiter and Saturn. Resonance locking also provides solutions to several problems posed by current measurements: it naturally explains the exceptionally small Q governing Rhea's migration, it allows the large heating rate of Enceladus to be achieved in an equilibrium eccentricity configuration, and it resolves evolutionary problems arising from present-day migration/heating rates.

Additional Information

© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 March 9. Received 2016 March 9. In original form 2016 January 21. First published online March 15, 2016. We thank Burkhard Militzer, Carolyn Porco, Francis Nimmo, Yanqin Wu, Dong Lai, and Peter Goldreich for useful discussions. JF acknowledges partial support from NSF under grant no. AST-1205732 and through a Lee DuBridge Fellowship at Caltech. JL is supported by TAC and CIPS at UC Berkeley. EQ was supported in part by a Simons Investigator award from the Simons Foundation and the David and Lucile Packard Foundation.

Attached Files

Published - MNRAS-2016-Fuller-3867-79.pdf

Submitted - 1601.05804v1.pdf


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