Spreading pressure bumps in gas-dust discs can stall planet migration via planet-vortex interactions
Abstrakt
We investigate the gravitational interaction between low- to intermediate-mass planets (M-p is an element of [0.06 - 210] M-circle plus) and two previously formed pressure bumps in a gas-dust protoplanetary disc. We explore how the disc structure changes due to planetinduced perturbations and also how the appearance of vortices affects planet migration.
We use multifluid 2D hydrodynamical simulations and the dust is treated in the pressureless-fluid approximation, assuming a single grain size of 5 mu m. The initial surface density profiles containing two bumps are motivated by recent observations of the protoplanetary disc HD163296.
When planets are allowed to migrate, either a single planet from the outer pressure maximum or two planets from each pressure maximum, the initial pressure bumps quickly spread and merge into a single bump which is radially wide and has a very low amplitude. The redistribution of the disc material is accompanied by the Rossby Wave Instability and an appearance of mini-vortices that merge in a short period of time to form a large vortex.
The large vortex induces perturbations with a spiral wave pattern that propagate away from the vortex as density waves. We found that these vortex-induced spiral waves strongly interact with the spiral waves generated by the planet and we called this mechanism the 'Faraway Interaction'.
It facilitates much slower and/or stagnant migration of the planets and it excites their orbital eccentricities in some cases. Our study provides a new explanation for how rocky planets can come to have a slow migration in protoplanetary discs where vortex formation occurs.