On the dynamical evolution of two-planet extrasolar systems orbiting one of the stars of wide binaries separated by less than 3000 au

Abstract

In recent years several extrasolar planetary systems have been discovered orbiting one of the stars in a wide binary star system. When the separation between the stars is less than 3000 au, the planets in these systems tend to have orbits with low eccentricity. However, when the planetary system has two planets, their orbits can range from moderate to high eccentricities. To understand this bimodal dynamical distribution of the planetary population, we have developed an analytical model to analyse the whole phase space of a hierarchical four body system. We have found that two-planet extrasolar systems in wide binary stars with separations of less than 3000 au are unlikely to be affected by Galactic perturbations. Therefore, the present configuration of these planetary systems could have resulted from other dynamic processes.