Asteroid flux towards circumprimary habitable zones in binary star systems: II. Dynamics

Abstract

Secular and mean motion resonances (MMR) are effective perturbations for shaping planetary systems. In binary star systems, they play a key role during the early and late phases of planetary formation, as well as for the dynamical stability of a planetary system. In this study, we aim to correlate the presence of orbital resonances with the rate of icy asteroids crossing the habitable zone (HZ), from a circumprimary disk of planetesimals in various binary star systems. We modelled a belt of small bodies in the inner and outer regions, interior and exterior to the orbit of a gas giant planet, respectively. The planetesimals are equally placed around a primary G-type star and move under the gravitational influence of the two stars and the gas giant. We numerically integrated the system for 50 Myr, considering various parameters for the secondary star. Its stellar type varies from a M- to F-type; its semimajor axis is either 50 au or 100 au, and its eccentricity is either 0.1 or 0.3. For comparison, we also varied the gas giant's orbital and physical parameters. Our simulations highlight that a disk of planetesimals will suffer from perturbations owing to a perturbed gas giant, mean motion, and secular resonances. We show that a secular resonance -- with location and width varying according to the secondary star's characteristics -- can exist in the icy asteroid belt region and overlap with MMRs which have an impact on the dynamical lifetime of the disk. In addition, we point out that in any case, the 2:1 MMR, the 5:3 MMR and the secular resonance are powerful perturbations for the flux of icy asteroids towards the HZ and the transport of water therein.