Vertically shearing streaming instabilities in protoplanetary disks

Min-Kai Lin^1*

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan

* Presenter:Min-Kai Lin, email:mklin@asiaa.sinica.edu.tw

The streaming instability between dust and gas in protoplanetary disks is widely considered as the de facto mechanism for the formation of planetesimals - the building blocks of planets. In its simplest form, the linear instability can be captured in unstratified disk models that represent the midplane of protoplanetary disks. However, real disks have a vertical structure as dust grains settle towards the midplane. I present the first linear stability analyses of vertically stratified, dusty protoplanetary disks. I find, consistent with early numerical simulations, that the dominant instability in stratified disks is one driven by the vertical gradient of the dusty-gas' rotation velocity, in combination with partial dust-gas coupling. These "vertically-shearing streaming instabilities" grow much faster, although on smaller scales, than classic streaming instabilities. I briefly discuss the potential effect of vertically-shearing streaming instabilities in planetesimal formation.

Keywords: planet formation, hydrodynamics, instabilities, protoplanetary disks