Diversity of planetary systems from evolution of solids in protoplanetary disks

Abstract

We have developed and applied a model designed to track simultaneously the evolution of gas and solids in protoplanetary disks from an early stage, when all solids are in the dust form, to the stage when most solids are in the form of a planetesimal swarm. The model is computationally efficient and allows for a global, comprehensive approach to the evolution of solid particles due to gas-solid coupling, coagulation, sedimentation, and evaporation/condensation. The co-evolution of gas and solids is calculated for 107 yr for several evolution regimes and starting from a comprehensive domain of initial conditions. The output of a single evolutionary run is a spatial distribution of mass locked in a planetesimal swarm. Because swarm's mass distribution is related to the architecture of a nascent planetary system, diversity of swarms is taken as a proxy for a diversity of planetary systems. We have found that disks with low values of specific angular momentum are bled out of solids and do not form planetary systems. Disks with high and intermediate values of specific angular momentum form diverse planetary systems. Solar-like planetary systems form from disks with initial masses ≤0.02 M⊙ and angular momenta ≤3 × 1052 g cm2 s-1. Planets more massive than Jupiter can form at locations as close as 1 AU from the central star according to our model.