Formation of giant planets in disks with different metallicities

¹ Nicolaus Copernicus Astronomical Center, Bartycka 18, Warsaw, 00-716, Poland e-mail: [kornet;mnr]@camk.edu.pl
² UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064, USA e-mail: peter@ucolick.org
³ Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, TX 77058, USA e-mail: tom@lpi.usra.edu

Received: 20 July 2004
Accepted: 20 September 2004

Abstract

We present the first results from simulations of processes leading to planet formation in protoplanetary disks with different metallicities. For a given metallicity, we construct a two-dimensional grid of disk models with different initial masses and radii (M₀, R₀). For each disk, we follow the evolution of gas and solids from an early evolutionary stage, when all solids are in the form of small dust grains, to the stage when most solids have condensed into planetesimals. Then, based on the core accretion – gas capture scenario, we estimate the planet-bearing capability of the environment defined by the final planetesimal swarm and the still evolving gaseous component of the disk. We define the probability of planet-formation, P_p, as the normalized fractional area in the (M₀, ) plane populated by disks that have formed planets inside 5 AU. With such a definition, and under the assumption that the population of planets discovered at  AU is not significantly contaminated by planets that have migrated from  AU, our results agree fairly well with the observed dependence between the probability that a star harbors a planet and the star's metal content. The agreement holds for the disk viscosity parameter α ranging from 10^-3 to 10^-2, and it becomes much poorer when the redistribution of solids relative to the gas is not allowed for during the evolution of model disks.