Razor-thin dust layers in protoplanetary disks: Limits on the vertical shear instability
arXiv:2210.13413 · doi:10.1051/0004-6361/202244218
Abstract
Context: Recent observations with the Atacama Large Millimeter Array (ALMA) have shown that the large dust aggregates observed at millimeter wavelengths settle to the midplane into a remarkably thin layer. Aims: We intend to find out if the geometric thinness of these layers is evidence against the vertical shear instability (VSI) operating in these disks. Methods: We performed hydrodynamic simulations of a protoplanetary disk with a locally isothermal equation of state, and let the VSI fully develop. We sprinkled dust particles and followed their motion as they got stirred up by the VSI. We determined for which grain size the layer becomes geometrically thin enough to be consistent with ALMA observations. We then verified if, with these grain sizes, it is still possible to generate a moderately optically thick layer at millimeter wavelengths, as observations appear to indicate. Results: We found that even very large dust aggregates with Stokes numbers close to unity get stirred up to relatively large heights above the midplane by the VSI, which is in conflict with the observed geometric thinness. For grains so large that the Stokes number exceeds unity, the layer can be made to remain thin, but we show that it is hard to make dust layers optically thick at ALMA wavelengths (e.g., tau(1.3mm)>=1) with such large dust aggregates. Conclusions: We conclude that protoplanetary disks with geometrically thin midplane dust layers cannot be VSI unstable, at least not down to the disk midplane. Explanations for the inhibition of the VSI include a reduced dust-to-gas ratio of the small dust grains that are responsible for the radiative cooling of the disk. A reduction of small grains by a factor of between 10 and 100 is sufficient to quench the VSI. Such a reduction is plausible in dust growth models, and still consistent with observations at optical and infrared wavelengths.
Accepted for publication in Astronomy & Astrophysics
References in corpus (20)
- PLUTO: a Numerical Code for Computational Astrophysics
- Gas- and dust evolution in protoplanetary disks
- Radiative transfer in very optically thick circumstellar disks
- Measuring turbulent motion in planet-forming disks with ALMA: A detection around DM Tau and non-detections around MWC 480 and V4046 Sgr
- Dust retention in protoplanetary disks
- Vertical shear instability in accretion disc models with radiation transport
- On the formation of multiple concentric rings and gaps in protoplanetary disks
- A highly settled disk around Oph 163131
- Global MHD simulations of stratified and turbulent protoplanetary discs. II. Dust settling
- Radiation Hydrodynamical Turbulence In Protoplanetary Disks: Numerical Models and Observational Constraints
- Particle dynamics in discs with turbulence generated by the vertical shear instability
- Gas and dust dynamics in starlight-heated protoplanetary disks
- Dust settling against hydrodynamic turbulence in protoplanetary discs
- How dust fragmentation may be beneficial to planetary growth by pebble accretion
- Anisotropic hydrodynamic turbulence in accretion disks
- High Resolution Parameter Study of the Vertical Shear Instability
- Impact of Local Pressure Enhancements on Dust Concentration inTurbulent Protoplanetary Discs
- Magnetised Winds in Transition Discs I: 2.5D Global Simulations
- Wavelike nature of the vertical shear instability in global protoplanetary disks
- The saturation of the VSI in protoplanetary disks via parametric instability
Cited by in corpus (19)
- Porous Dust Particles in Protoplanetary Disks: Application to the HL Tau Disk
- Modeling planet-induced gaps and rings in ALMA disks: the role of in-plane radiative diffusion
- Constraining turbulence in protoplanetary discs using the gap contrast: an application to the DSHARP sample
- Dust Coagulation Reconciles Protoplanetary Disk Observations with the Vertical Shear Instability. I. Dust Coagulation and the VSI Dead Zone
- Vertical shear instability in two-moment radiation-hydrodynamical simulations of irradiated protoplanetary disks I. Angular momentum transport and turbulent heating
- Vertical shear instability in two-moment radiation-hydrodynamical simulations of irradiated protoplanetary disks II. Secondary instabilities and stability regions
- Two saturated states of the vertical shear instability in protoplanetary disks with vertically varying cooling times
- Instabilities in dusty non-isothermal proto-planetary discs
- Hydrodynamic turbulence in disks with embedded planets
- Massive Protostellar Disks as a Hot Laboratory of Silicate Grain Evolution
- On the interaction of pebble accreting embryos with the gaseous disc: importance of thermal forces
- Strong clumping in global streaming instability simulations with a dusty fluid
- UV-processing of icy pebbles in the outer parts of VSI-turbulent disks
- Starlight-driven flared-staircase geometry in radiation hydrodynamic models of protoplanetary disks
- Dynamics of small, constant size particles in a protoplanetary disk with an embedded protoplanet
- Measuring the Numerical Viscosity in Simulations of Protoplanetary Disks in Cartesian Grids -- The Viscously Spreading Ring Revisited
- Linear bending wave propagation in laminar and turbulent discs
- How two-dimensional are planet-disc interactions? II. Radiation hydrodynamics and suitable cooling prescriptions
- Hydrodynamical simulations of the vertical shear instability with dynamic dust and cooling rates in protoplanetary disks