Dynamical evolution in multi-planet system due to bodily tides

Detailed modelling of the dynamics of planets around low mass stars requires to include tidal and permanent deformation effects. Several exoplanets recently discovered are expected to be trapped in low order spin-orbit resonances due to the interaction with the host star. Different attempts to describe the spin-orbit coupling have been built on the seminal work by Kaula (1964) who was the first to connect the tidal lagging of a solid body with the energy dissipation in the mantle. This opened the door for the inclusion of novel rheological models aimed to couple the spin-orbit state of an exoplanet with the mechanisms of internal energy dissipation.

In my bachelor project I worked out the problem of estimating the spin-orbit state when tidal and permanent deformation torques act on planet-star systems. I was particularly interested in the tidal framework presented in Efroimsky (2012) (one of the many branches derived from Kaula’s work) which capitalizes on Andrade’s rheological model.

I co-authored a publication that revisited the case of the GJ 667C multiplanetary system The science question of this work is: does the probability for planets b and c of reaching a low order spin-orbit resonance varies significantly due to the orbital perturbation by other planets? Numerical simulations for the rotational evolution coupled with the output of an N-body orbital integration found that the final rotational state is not significantly affected by the presence of the remaining planets.

Take a look to the publication if interested in learning more.