Wladimir Lyra (JPL) : Formation and retention of planets in disks

The ill fate of the building blocks of planets in gaseous disks around young stars stands as one of the major unsolved problems in the theory of planet formation. Our current level of understanding indicates that solids in circumstellar disks migrate into the star or are destroyed in collisions on timescales that are much too short to allow the assembly of kilometer sized bodies that can grow further without such problems. In this seminar I will review how the most recent models rely on turbulent motions in the disk in order to breach these barriers. Special focus will be given to the possibility of persistent storm systems (aka vortices) in accretion disks, that have long been considered as a route for fast planet formation, and shown to lead to the assemblage of planetary embryos of Moon to Mars mass. Once the planets are formed in the hydro simulations, we follow the multi-million year N-body evolution of the ensemble, showing that they eventually coallesce into bodies of the order of tens of Earth masses.