Instabilities in dusty non-isothermal proto-planetary discs

Abstract

Protoplanetary discs (PPDs) can host a number of instabilities that may partake directly or indirectly in the process of planetesimal formation. These include the Vertical Shear Instability (VSI), Convective Overstability (COS), Streaming Instability (SI), and Dust Settling Instability (DSI), to name a few. Notably, the VSI and COS have mostly been studied in purely gaseous discs, while the SI and DSI have only been analyzed in isothermal discs. How these instabilities operate under more general conditions is therefore unclear. To this end, we devise a local model of a PPD describing a non-isothermal gas interacting with a single species of dust via drag forces. Using this, we find that dust drag sets minimum length scales below which the VSI and COS are suppressed. Similarly, we find that the SI can be suppressed on sufficiently small scales by the gas' radial buoyancy if it cools on roughly a dynamical timescale. We show that the DSI can be effectively stabilized by vertical buoyancy, except at special radial and vertical length scales. We also find novel instabilities unique to a dusty, non-isothermal gas. These result in a dusty analog of the COS that operates in slowly cooled discs, and a dusty version of the VSI that is strongly enhanced by dust settling. We briefly discuss the possible implications of our results on planetesimal formation.

40 pages, 26 figures

References in corpus (13)

• Protoplanetary Disk Structures in Ophiuchus
• Convective Overstability in radially stratified accretion disks under thermal relaxation
• Vertical shear instability in accretion disc models with radiation transport
• Radiation Hydrodynamical Turbulence In Protoplanetary Disks: Numerical Models and Observational Constraints
• Convective overstability in accretion disks: 3D linear analysis and nonlinear saturation
• Particle dynamics in discs with turbulence generated by the vertical shear instability
• Gas and dust dynamics in starlight-heated protoplanetary disks
• On the vertical-shear instability in astrophysical discs
• A thermodynamic view of dusty protoplanetary disks
• Dust settling against hydrodynamic turbulence in protoplanetary discs
• Local models of astrophysical discs
• Stratified and vertically-shearing streaming instabilities in protoplanetary disks
• Impact of Local Pressure Enhancements on Dust Concentration inTurbulent Protoplanetary Discs