Spin evolution of Earth-sized exoplanets, including atmospheric tides and core-mantle friction

D. Cunha, A. C. M. Correia, J. Laskar

Abstract
Planets with masses between 0.1 − 10 M_⊕ are believed to host dense atmospheres. These atmospheres can play an important role on the planet’s spin evolution, since thermal atmospheric tides, driven by the host star, may counterbalance gravitational tides. In this work we study the long-term spin evolution of Earth-sized exoplanets. We generalize previous works by including the effect of eccentric orbits and obliquity. We show that under the effect of tides and core-mantle friction, the obliquity of the planets evolve either to 0º or 180º. The rotation of these planets is also expected to evolve into a very restricted number of equilibrium configurations. In general, none of this equilibria is synchronous with the orbital mean motion. The role of thermal atmospheric tides becomes more important for Earth-sized planets in the habitable zones of their systems, so they cannot be neglected when we search for their potential habitability.

Keywords
Planets and satellites: atmospheres; Planets and satellites: dynamical evolution and stability

International Journal of Astrobiology
July 2014

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