A New Hybridn-Body-Coagulation Code for the Formation of Gas Giant Planets

We describe an updated version of our hybrid N -body-coagulation code for planet formation. In addition to the features of our 2006–2008 code, our treatment now includes algorithms for the one-dimensional evolution of the viscous disk, the accretion of small particles in planetary atmospheres, gas accretion onto massive cores, and the response of N -bodies to the gravitational potential of the gaseous disk and the swarm of planetesimals. To validate the N -body portion of the algorithm, we use a battery of tests in planetary dynamics. As a first application of the complete code, we consider the evolution of Pluto-mass planetesimals in a swarm of 0.1–1 cm pebbles. In a typical evolution time of 1–3 Myr, our calculations transform 0.01–0.1 M ☉ disks of gas and dust into planetary systems containing super-Earths, Saturns, and Jupiters. Low-mass planets form more often than massive planets; disks with smaller α form more massive planets than disks with larger α. For Jupiter-mass planets, masses of solid cores are 10–100 M ⊕ .