Institute for Advanced Study Astrophysics Seminar

Planets are built from small dust grains embedded in gaseous protoplanetary disks. As such, the associated gas dynamics and dust-gas interactions play key roles in modern theories of planet formation and evolution. In particular, several hydrodynamic instabilities have been identified in the cold, planet-forming regions of these disks. They can hinder dust growth through turbulent stirring, but could also facilitate it by generating large-scale, dust-collecting structures and triggering additional dust-gas "streaming" instabilities. Which effect dominates depends on the instability and disk conditions. I will present recent analytical and numerical studies of hydrodynamic turbulence and structure formation through the vertical shear instability and convective overstabilities, and generalizations of the classical streaming instability for planetesimal formation to account for realistic disk conditions such as accretion flows and magnetic fields. I will describe new challenges these considerations reveal, as well as potentially new pathways for planetesimal formation that may explain the ubiquity of planets in the universe.