A recent effort studying the diffusion and scattering of dust particles in self-gravity driven turbulent protoplanetary disks.

8-panelIn one of my previous works, we discovered the gravito-turbulence (see paper on ADS and arXiv) properties are largely different than that of the MRI-driven turbulence. That will most certainly affect the dust growth and redistribution in such a different environment. In this recent work (see paper on ADS and arXiv), we investigate the radial diffuse and relative velocities of dust particles of a range of sizes, from Stokes number of 10-3 to 103 (0.1 mm – 0.1 km for disk ~ 100 AU),  with two-dimensional (in the disk plane), hybrid (particle and gas) simulations. Gravito-turbulent disks can exhibit stronger gravitational stirring than MRI-active disks, resulting in greater radial diffusion and larger eccentricities and relative speeds for large particles. The agglomeration of large particles into planetesimals by pairwise collisions is therefore disfavored in gravito-turbulent disks. However, the relative speeds of intermediate-size particles tstopΩ∼1 are significantly reduced as such particles are collected by gas drag and gas gravity into coherent filament-like structures with densities high enough to trigger gravitational collapse. First-generation planetesimals may form via gravitational instability of dust in marginally gravitationally unstable gas disks.