Planetary Formation and Orbital Stability in Binary Star Systems

Among the presently known extrasolar planetary systems, almost 20 are in binary star systems but their orbital parameters are far different from those predicted by the standard model of planetary formation. In our work we investigated under which assumptions terrestrial and giant planets could form in such complex dynamical environments, using the systems of alpha Centauri and gamma Cephei as models in our simulations. We studied the possibility of planetesimal accretion and modeled the formation of terrestrial planets (alpha Centauri case) and of the cores of giant planets (gamma Cephei case). Our results show that planetary formation is possible in binary star systems and that the standard model could explain the formation of the observed planets. We studied the dynamical stability of planetary orbits in gamma Cephei by using the FMA method: our results show the dependence of the critical semimajor axis from the orbital inclination and eccentricity.