Aims: We investigate the behaviour of dust in protoplanetary disks under the action of gas drag in the presence of a planet. Our goal is twofold: to determine the spatial distribution of dust depending on grain size and planet mass, and therefore to
provide a framework for interpretation of coming observations and future studies of planetesimal growth. Method: We numerically model the evolution of dust in a protoplanetary disk using a two-fluid (gas + dust) Smoothed Particle Hydrodynamics (SPH) code, which is non-self-gravitating and locally isothermal. The code follows the three dimensional distribution of dust in a protoplanetary disk as it interacts with the gas via aerodynamic drag. In this work, we present the evolution of a minimum mass solar nebula (MMSN) disk comprising 1% dust by mass in the presence of an embedded planet. We run a series of simulations which vary the grain size and planetary mass to see how they affect the resulting disk structure. Results: We find that gap formation is much more rapid and striking in the dust layer than in the gaseous disk and that a system with a given stellar, disk and planetary mass will have a completely different appearance depending on the grain size. For low mass planets in our MMSN disk, a gap can open in the dust disk while not in the gas disk. We also note that dust accumulates at the external edge of the planetary gap and speculate that the presence of a planet in the disk may enhance the formation of a second planet by facilitating the growth of planetesimals in this high density region.
Our objective is to study the vertical dust distribution in the circumbinary ring of the binary system GG Tau and to search for evidence of stratification, one of the first steps expected to occur during planet formation. We present a simultaneous
analysis of four scattered light images spanning a range of wavelength from 800 nm to 3800 nm and compare them with (i) a parametric prescription for the vertical dust stratification, and (ii) with the results of SPH bi-fluid hydrodynamic calculations. The parametric prescription and hydrodynamical calculations of stratification both reproduce the observed brightness profiles well. These models also provide a correct match for the observed star/ring integrated flux ratio. Another solution with a well-mixed, but ``exotic, dust size distribution also matches the brightness profile ratios but fails to match the star/ring flux ratio. These results give support to the presence of vertical stratification of the dust in the ring of GG Tau and further predict the presence of a radial stratification also.
