We investigate the response of an accretion disk to the presence of
a perturbing protoplanet embedded in the disk through time
dependent hydrodynamical simulations.
The disk is treated as a two dimensional viscous fluid
and the planet is kept on a fixed circular orbit.
We run a set of simulations varying the planet
mass, and the viscosity and temperature of the disk, where all runs
are followed until they reach a quasi-equilibrium state.
We find that for planetary masses above a certain minimum mass,
already 3 M_Jup for a standard viscosity, the disk makes a transition
from a laminar (nearly circular) state into an eccentric state.
Increasing the planetary mass yields to a saturation of disk eccentricity
with a maximum value of around 0.25.
The transition to the eccentric state is driven by the excitation of
an m=2 spiral wave at the outer 1:3 Lindblad resonance.
The effect occurs only if the planetary masses are large enough to clear
a sufficiently wide and deep gap to reduce the damping effect of the
outer 1:2 Lindblad resonance.
An increase in viscosity and temperature in the disk, which both tend to
close the gap, have an advert influence on the disk eccentricity.
In the eccentric state the mass accretion rate onto the planet is
greatly enhanced, an effect that may ease the formation of massive
planets beyond about 5 M_Jup that are otherwise difficult to
reach.
Accepted Version, October 2005
pdf-file (ca. 0.5 MB)
Related movies for an Eccentric Disk:
4 M_Jup planet, on circular orbit
rphi-coord. (long run, a few hundred orbits, delta t = 5 orbits, ca. 4.0 MB)
sigma-profile (long run, ca. 4.0 MB)
rphi-coord. (short run, a few orbits, delta t = 0.05 orbits, ca. 1.0 MB)
xy-coord. (short run, ca. 1.0 MB)
