Saving Planetary Systems: Dead Zones & Planetary Migration
نویسندگان
چکیده
The tidal interaction between a disk and a planet leads to the planet’s migration. It is widely believed that this mechanism explains the variety of orbital radii of extrasolar planets. A long-standing question regarding this mechanism is how to stop the migration before planets plunge into their central stars. In this paper, we propose a new, simple mechanism to significantly slow down planet migration, and test the possibility by using a hybrid numerical integrator to simulate the disk-planet interaction. The key component of the scenario is the role of low viscosity regions in protostellar disks known as dead zones. A region of low viscosity affects planetary migration in two ways. First of all, it allows a smaller-mass planet to open a gap, and hence switch the faster type I migration (pre-gap-opening migration) to the slower type II migration (post-gap-opening migration). Secondly, a low viscosity slows down type II migration itself, because type II migration is directly proportional to the viscosity. We present numerical simulations of planetary migration in disks by using a hybrid symplectic integrator-gas dynamics code. Assuming that the disk viscosity Current location: Department of Physics & Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208-0834, USA, e-mail: [email protected] Origins Institute, ABB 241, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4M1, Canada
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