Paper: astro-ph/0601222
Date: Tue, 10 Jan 2006 21:14:57 GMT (256kb)

Title: Surface density jumps as planet traps

Authors: F. Masset (Saclay & IA-UNAM), A. Morbidelli (OCA), A. Crida (OCA) and
J. Ferreira (LAOG)

Comments: accepted for publication in ApJ
\\
[Abridged] The tidal torque exerted by a protoplanetary disk with power law
surface density and temperature profiles onto an embedded protoplanetary embryo
is generally a negative quantity that leads to the embryo inwards migration.
Here we investigate how the tidal torque balance is affected at a disk surface
density radial jump. The jump has two consequences :

- it affects the differential Lindblad torque. In particular if the disk is
merely empty on the inner side, the differential Lindblad torque almost amounts
to the large negative outer Lindblad torque.

- It affects the corotation torque, which is a quantity very sensitive to the
local gradient of the disk surface density. In particular if the disk is
depleted on the inside and if the jump occurs radially over a few pressure
scale-heights, the corotation torque is a positive quantity that is much larger
than in a power-law disk.

We show by means of customized numerical simulations of low mass planets
embedded in protoplanetary nebulae with a surface density jump that the second
effect is dominant, that is that the corotation torque largely dominates the
differential Lindblad torque on the edge of a central depletion. As a
consequence the type I migration of low mass objects reaching the jump should
be halted, and all these objects should be trapped there.

\\ ( http://arXiv.org/abs/astro-ph/0601222 , 256kb)