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Wednesday 30 Nov 2022Interaction between fast tides and convection with application to giant planets and solar type stars

Caroline Terquem - University of Oxford

Physics building, 4th floor 14:00-15:00

Dissipation of tidal oscillations in stars and giant planets plays a very important role in shaping the orbits of binary systems and systems of moons. The theory developed in the last 55 years has been successful at explaining dissipation in bodies which are convectively stable. However, it badly fails to explain dissipation in convective flows when the convective turnover timescale is larger than the tidal period, as is the case in the envelopes of solar type stars or giant planets. We propose a new formalism to calculate the exchange of energy between tides and a convective flow in this regime. We argue that the standard picture, in which the tides are described as a mean shear flow which is damped by fluctuating convective eddies, is inconsistent and should be reversed. Assuming that energy is always transferred from the tides to the convective flow, and not the other way round, this formalism yields values for the tidal dissipation factor of Jupiter and Saturn, for the circularization periods of solar-type binaries and for that of extrasolar planets in good overall agreement with observations.

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