Dynamical evolution of close-in binary systems formed by a super-earth and its host star

LUNA, SANTIAGO; NAVONE, HUGO; M.D. MELITA.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2020 vol. 641 p. 109 - 115

0004-6361

We have developed a formalism to study the secular evolution of a binary system, including the interaction due to the tides that each body raises on the other one. We also consider the influence of the J2 -related secular terms on the orbital evolution and the triaxiality-caused torque on the rotational evolution, both associated only to one of the bodies. We apply these set of equations to the study of the orbital and rotational evolution of a binary system composed by a rocky planet and its host star in order to characterize the dynamical evolution, particularly near spin-orbit resonances. We use the equations of motion that give the time evolution of the orbital elements and the spin rates of each body to study the time evolution of the Kepler-21 system as an example of application of the formalism developed. We have obtained a set of equations of motion without singularities for vanishing eccentricities and inclinations. This set gives, on one hand, the time evolution of the orbital elements due to the tidal potentials generated by both partners of the system and the triaxiality of one of them. On the other hand, it gives the time evolution of the stellar spin rate due to the corresponding tidal torque and of the planet´s rotation angle due to both the tidal and triaxiality-caused torque. We found that, for the parameters and the initial conditions explored, the tidally and triaxiality induced modifications of the tidal modes is more significative than expected and that the time of tidal synchronization depends strongly on the values of the rheological parameters.