Vertical shear instability with dust evolution and consistent cooling times. On the importance of the initial dust distribution

Abstract

Context. Gas in protoplanetary disks mostly cools via thermal accommodation with dust particles. Thermal relaxation is thus highly sensitive to the local dust size distributions and the spatial distribution of the grains. So far, the interplay between thermal relaxation and gas turbulence has not been dynamically modeled in hydrodynamic simulations of protoplanetary disks with dust. Aims. We aim to study the effects of the vertical shear instability (VSI) on the thermal relaxation times, and vice versa. We are particularly interested in the influence of the initial dust grain size on the VSI and whether the emerging turbulence is sustained over long timescales. Results. We find that the emergence of the VSI is strongly dependent on the initial dust grain size. Coagulation also counteracts the emergence of hydrodynamic turbulence in our simulations, as shown by others before. Starting a simulation with larger grains (100 $\mu$m) generally leads to a less turbulent outcome. While the inner disk regions (within $\sim$ 70 au) develop turbulence in all three simulations, we find that the simulations with larger particles do not develop VSI in the outer disk. Conclusions. Our simulations with dynamically calculated thermal accommodation times based on the drifting and settling dust distribution show that the VSI, once developed in a disk, can be sustained over long timescales, even if grain growth is occurring. The VSI corrugates the dust layer and even diffuses the smaller grains into the upper atmosphere, where they can cool the gas. Whether the instability can emerge for a specific stratification depends on the initial dust grain sizes and the initial dust scale height. If the grains are initially $\gtrsim$ 100 $\mu$m and if the level of turbulence is initially assumed to be low, we find no VSI turbulence in the outer disk regions.

arXiv comment6 pages, 3 figures, accepted for publication as a Letter to the Editor in Astronomy and Astrophysics

References in corpus (24)

• Nonlinear Outcome of Gravitational Instability in Cooling, Gaseous Disks
• A simple model for the evolution of the dust population in protoplanetary disks
• Linear and nonlinear evolution of the vertical shear instability in accretion discs
• Nonlinear Outcome of Gravitational Instability in Disks with Realistic Cooling
• Cooling Requirements for the Vertical Shear Instability in Protoplanetary Disks
• Convective Overstability in radially stratified accretion disks under thermal relaxation
• Zombie Vortex Instability I: A Purely Hydrodynamic Instability to Resurrect the Dead Zones of Protoplanetary Disks
• Particle dynamics in discs with turbulence generated by the vertical shear instability
• Gas and dust dynamics in starlight-heated protoplanetary disks
• The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? III. Sedimentation driven coagulation inside the snow-line
• Low dust emissivities and radial variations in the envelopes of Class 0 protostars: a signature of early grain growth?
• Dust settling against hydrodynamic turbulence in protoplanetary discs
• Efficiency of thermal relaxation by radiative processes in protoplanetary discs: constraints on hydrodynamic turbulence
• On the coexistence of the streaming instability and the vertical shear instability in protoplanetary disks
• Mean gas opacity for circumstellar environments and equilibrium temperature degeneracy
• The Sandwich Mode for Vertical Shear Instability in Protoplanetary Disks
• Zombie Vortex Instability. III. Persistence with Nonuniform Stratification and Radiative Damping
• High Resolution Parameter Study of the Vertical Shear Instability II: Dependence on temperature gradient and cooling time
• The coexistence of the streaming instability and the vertical shear instability in protoplanetary disks: Planetesimal formation thresholds explored in two-dimensional global models
• Three-temperature radiation hydrodynamics with PLUTO: Tests and applications to protoplanetary disks
• Dust Coagulation Reconciles Protoplanetary Disk Observations with the Vertical Shear Instability. I. Dust Coagulation and the VSI Dead Zone
• Two saturated states of the vertical shear instability in protoplanetary disks with vertically varying cooling times
• Gravito-turbulence in irradiated protoplanetary discs
• Gravito-turbulence in local disk simulations with an adaptive moving mesh

Cited by in corpus (1)

• Hydrodynamical simulations of the vertical shear instability with dynamic dust and cooling rates in protoplanetary disks