Tidal modulations and the habitability of exoplanetary systems

Abstract

ABSTRACTThe Earth currently experiences rich tidal modulations by virtue of the fact that the tidal forces generated by the Sun and the Moon are approximately a factor of 2 removed from each other. This datum has been adduced by some scientists as one of the major drivers of the origin and evolution of (complex) life on the Earth (e.g. evolution of tetrapods). In this paper, we investigate the conditions under which terrestrial planets in the habitable zone can undergo strong tidal modulations akin to those documented on the Earth. By using an analytical model, we show that higher mass stars are more conducive to hosting potentially habitable planets with such moons, and that late-type M-dwarfs with masses $\lesssim 0.1\, {\rm M}_\odot$ might not host temperate Earth-analogues that fulfil the aforementioned criterion regarding tidal modulations. We also find that the Moon may perhaps be close to the maximal allowed mass limit compatible with producing large tidal modulations.