Gap Opening by Extremely Lowmass Planets in a Viscous Disk
Abstract
By numerically integrating the compressible NavierStokes equations in two dimensions, we calculate the criterion for gap formation by a very low mass (q ~ 10^{4}) protoplanet on a fixed orbit in a thin viscous disk. In contrast with some previously proposed gapopening criteria, we find that a planet can open a gap even if the Hill radius is smaller than the disk scale height. Moreover, in the lowviscosity limit, we find no minimum mass necessary to open a gap for a planet held on a fixed orbit. In particular, a Neptunemass planet will open a gap in a minimum mass solar nebula with suitably low viscosity (α <~ 10^{4}). We find that the mass threshold scales as the square root of viscosity in the low mass regime. This is because the gap width for critical planet masses in this regime is a fixed multiple of the scale height, not of the Hill radius of the planet.
 Publication:

The Astrophysical Journal
 Pub Date:
 May 2013
 DOI:
 10.1088/0004637X/769/1/41
 arXiv:
 arXiv:1302.1934
 Bibcode:
 2013ApJ...769...41D
 Keywords:

 hydrodynamics;
 methods: numerical;
 planetdisk interactions;
 planets and satellites: formation;
 protoplanetary disks;
 Astrophysics  Earth and Planetary Astrophysics;
 Physics  Computational Physics;
 Physics  Fluid Dynamics
 EPrint:
 ApJ accepted