Abstract
We study the migration and resonant capture of planetesimals in a planetary system consisting of a gaseous disk analogous to the primordial solar nebula and a Neptune-like planet. Using a simple treatment of the drag force, we find that planetesimals are mainly trapped in the 3:2 and 2:1 resonances and that the resonant populations are correlated with the gaseous drag strength in a sense that the 3:2 resonant population increases with the stronger gaseous drag, but the 2:1 resonant population does not. Since planetesimals can lead to the formation of larger bodies similar to asteroids and Kuiper Belt objects, the gaseous drag can play an important role in the configuration of a planetary system. © 2007. The American Astronomical Society. All rights reserved.