Planets opening dust gaps in gas disks
  We investigate the interaction of gas and dust in a protoplanetary disk in the presence of a massive planet using a new two-fluid hydrodynamics code. In view of future observations of planet-forming disks we focus on the condition for gap formation in the dust fluid. While only planets more massive than 1 Jupiter mass (MJ) open up a gap in the gas disk, we find that a planet of 0.1 MJ already creates a gap in the dust disk. This makes it easier to find lower-mass planets orbiting in their protoplanetary disk if there is a significant population of mm-sized particles. 
Sijme-Jan Paardekooper (1) and Garrelt Mellema (2 and 1) ((1)   Sterrwacht Leiden, (2) ASTRON Dwingeloo)