Tides in the Atmospheres of Super-Earths

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• Pierre Auclair-Desrotour (OBSPM - CEA)
• Monday 25 April 2016, 16:00-17:00
• MR14, Centre for Mathematical Sciences, Wilberforce Road, Cambridge.

If you have a question about this talk, please contact Jean Teyssandier.

Tides can strongly affect the evolution of the spin of planets. Super-Earths presenting a solid core and an atmosphere are submitted to both gravitational tides caused by bodies’ mutual gravitational interactions and thermal tides resulting from stellar insolation. Thermal tides are particularly important for planets in the habitable zone where they drive the tidal response of the atmosphere (Correia & Laskar 2008). They play a key role for the equilibrium states of the spin, as in the case of Venus (Correia & Laskar 2004) and of telluric exoplanets (e.g. the numerical simulations by Leconte & al. 2015). Given the complex mechanisms involved in thermal tides, analytic models are essential to understand the dependence of the perturbation on the physics of the atmosphere and the tidal frequency. The one proposed in the 60’s by Lindzen and Chapman explains well thermal tides in the asymptotic regime of fast rotators but presents a singularity near synchronization. In this seminar, we will present a new analytic approach that generalizes these early works to all regimes of tidal perturbations. This model describes the mechanisms of tidal waves generated in the atmosphere by both gravitational and thermal tides. The tidal torque is computed as a function of the frequency of the forcing and agrees well with results obtained by direct numerical simulations based on General Circulation Models. We then use it to revisit the early works predicting the equilibrium rotation of Venus-like planets.

This talk is part of the DAMTP Astrophysics Seminars series.

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