Dust Evolution from Microscales to Disk Scales
Speaker: Thomas Pfeil (Flatiron Institute)
Abstract:
Planet formation begins with the coagulation of micrometer-sized dust grains in a protoplanetary disk. This particle growth not only provides the building material for planetesimals but also shapes the environments they form in. Aerodynamic drag forces between gas and dust determine how fast the grains drift and how efficiently they can be trapped in the frequently observed rings and vortices in protoplanetary disks. The size of the particles thus affects the available dust mass and composition throughout the disk. Dust also dominates the opacities and therefore regulates the thermal structure and the onset of hydrodynamic instabilities that depend on thermal relaxation. In my talk, I will present two recent applications of coupled multifluid simulations and dust coagulation models that capture the interplay of microphysics and large-scale dynamics in protoplanetary disks: Our simulations of planet-disk systems with dust coagulation quantify the amount of small dust grains that diffuse and drift through planet-induced gaps. These calculations constrain the composition and available mass of solids in the inner disk regions. We furthermore investigate the effects of dust evolution on protoplanetary disk turbulence, induced by the Vertical Shear Instability. Our simulations show that efficient dust coagulation can suppress turbulence in protoplanetary disks, due to the reduced collisional cooling in the dust-depleted upper layers. Understanding how dust coagulation influences the dynamics of protoplanetary disks is thus key to understanding the initial conditions for planet formation and to interpreting multi-wavelength observations.