Self-consistent model for dust-gas coupling in protoplanetary disks

Various physical processes that ensue within protoplanetary disks - including vertical settling of icy and rocky grains, radial drift solids, planetesimal formation, as well planetary accretion itself are facilitated by hydrodynamic interactions between H/He gas high-Z dust. The Stokes number, which quantifies the strength dust-gas coupling, thus plays a central role in disk evolution its poor determination constitutes an important source uncertainty theory planet formation. In this work, we present simple model for coupling demonstrate specified combination nebular rate, Ṁ , turbulence parameter a, profile number can be calculated unique way. Our indicates grows sublinearly with orbital radius, but increases dramatically across water-ice line. For fiducial parameters = 10 −8 M ⊙ per year α −3 our yields characteristic values on order St ~ −4 (corresponding to ~mm-sized silicate dust) inner nebula −1 grains few cm size) outer regions disk. Accordingly, solids expected settle into thin subdisk at large stellocentric distances, while remaining vertically mixed inside ice