Vortex formation and survival in protoplanetary discs subject to vertical shear instability

Manger, Natascha; Klahr, Hubert

doi:10.1093/mnras/sty1909

Cited by 67 publications

(119 citation statements)

References 44 publications

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“…We assumed axisymmetry throughout. This simplification overestimates the strength of VSI turbulence (Manger & Klahr 2018). For example, Stoll & Kley (2016) found that passive particles with Tstop = 0.002 can settle to H d 0.66Hg; whereas we find such particles remain perfectly mixed with the gas.…”

Section: Caveats and Outlooksmentioning

confidence: 54%

Dust settling against hydrodynamic turbulence in protoplanetary discs

Lin

2019

Monthly Notices of the Royal Astronomical Society

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Enhancing the local dust-to-gas ratio in protoplanetary discs is a necessary first step to planetesimal formation. In laminar discs, dust settling is an efficient mechanism to raise the dust-to-gas ratio at the disc midplane. However, turbulence, if present, can stir and lift dust particles, which ultimately hinders planetesimal formation. In this work, we study dust settling in protoplanetary discs with hydrodynamic turbulence sustained by the vertical shear instability. We perform axisymmetric numerical simulations to investigate the effect of turbulence, particle size, and solid abundance or metallicity on dust settling. We highlight the positive role of drag forces exerted onto the gas by the dust for settling to overcome the vertical shear instability. In typical disc models we find particles with a Stokes number ∼ 10 −3 can sediment to < ∼ 10% of the gas scale-height, provided that Σ d /Σ g > ∼ 0.02-0.05, where Σ d,g are the surface densities in dust and gas, respectively. This coincides with the metallicity condition for small particles to undergo clumping via the streaming instability. Super-solar metallicities, at least locally, are thus required for a self-consistent picture of planetesimal formation. Our results also imply that dust rings observed in protoplanetary discs should have smaller scale-heights than dust gaps , provided that the metallicity contrast between rings and gaps exceed the corresponding contrast in gas density.

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Section: Caveats and Outlooksmentioning

confidence: 54%

Dust settling against hydrodynamic turbulence in protoplanetary discs

Lin

2019

Monthly Notices of the Royal Astronomical Society

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“…We note that the Reynolds stresses measured in all three of our magnetized models are noisy and are smaller than those obtained in 3D simulations (α ∼ 10 −3 ; e.g. N13; Manger & Klahr 2018) which allow for better averaging. We find the same holds for hydrodynamic simulations.…”

Section: Radial Transportmentioning

confidence: 63%

“…We find the same holds for hydrodynamic simulations. The higher Reynolds stress in 3D is likely due to the formation of vortices (Richard et al 2016;Manger & Klahr 2018), though the kinetic energy fluctuations remain very similar between 2D and 3D. Further study with non-ideal MHD in 3D is needed to better constrain the range of Reynolds stress.…”

Section: Radial Transportmentioning

confidence: 99%

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Global Simulations of the Vertical Shear Instability with Nonideal Magnetohydrodynamic Effects

Cui

Bai

2020

ApJ

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The mechanisms of angular momentum transport and the level of turbulence in protoplanetary disks (PPDs) are crucial for understanding many aspects of planet formation. In recent years, it has been realized that the magneto-rotational instability (MRI) tends to be suppressed in PPDs due to non-ideal magnetohydrodynamic (MHD) effects, and the disk is primarily laminar with accretion driven by magnetized disk winds. In parallel, several hydrodynamic mechanisms have been identified that likely also generate vigorous turbulence and drive disk accretion. In this work, we study the interplay between MHD winds in PPDs with the vertical shear instability (VSI), one of the most promising hydrodynamic mechanisms, through 2D global non-ideal MHD simulations with ambipolar diffusion and Ohmic resistivity. For typical disk parameters, MHD winds can coexist with the VSI with accretion primarily wind-driven accompanied by vigorous VSI turbulence. The properties of the VSI remain similar to the unmagnetized case. The wind and overall field configuration are not strongly affected by the VSI turbulence showing modest level of variability and corrugation of midplane current sheet. Weak ambipolar diffusion strength or the enhanced coupling between gas and magnetic fields weakens the VSI. The VSI is also weakened with increasing magnetization, and characteristic VSI corrugation modes transition to low-amplitude breathing mode oscillations with strong magnetic fields.

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“…The trap distance d quantifies typical radial separation of the trap and τ trap a trap's typical lifetime. We set d = 5h g and τ trap to 100 orbits, as found numerically by Dittrich et al (2013); Manger & Klahr (2018).…”

Section: Pebble Flux-regulated Planetesimal Formationmentioning

confidence: 99%

Linking planetesimal and dust content in protoplanetary disks via a local toy model

Gerbig

Lenz

Klahr

2019

A&A

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Context. If planetesimal formation is an efficient process, as suggested by several models involving gravitational collapse of pebble clouds, then, before long, a significant part of the primordial dust mass should be absorbed in many km sized objects. A good understanding of the total amount of solids in the disk around a young star is crucial for planet formation theory. But as the mass of particles above the mm size cannot be assessed observationally, one must ask how much mass is hidden in bigger objects. Aims. We perform 0-d local simulations to study how the planetesimal to dust and pebble ratio is evolving in time and to develop an understanding of the potentially existing mass in planetesimals for a certain amount of dust and pebbles at a given disk age. Methods. We perform a parameter study based on a model considering dust growth, planetesimal formation and collisional fragmentation of planetesimals, while neglecting radial transport processes.Results. While at early times, dust is the dominant solid particle species, there is a phase during which planetesimals make up a significant portion of the total mass starting at approximately 10 4 − 10 6 yr. The time of this phase and the maximal total planetesimal mass strongly depend on the distance to the star R, the initial disk mass, and the efficiency of planetesimal formation . Planetesimal collisions are more significant in more massive disks, leading to lower relative planetesimal fractions compared to less massive disks. After approximately 10 6 yr, our model predicts planetesimal collisions to dominate, which resupplies small particles.Conclusions. In our model, planetesimals form fast and everywhere in the disk. For a given , we were able to relate the dust content and mass of a given disk to its planetesimal content, providing us with some helpful basic intuition about mass distribution of solids and its dependence on underlying physical processes.

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Vortex formation and survival in protoplanetary discs subject to vertical shear instability

Cited by 67 publications

References 44 publications

Dust settling against hydrodynamic turbulence in protoplanetary discs

Dust settling against hydrodynamic turbulence in protoplanetary discs

Global Simulations of the Vertical Shear Instability with Nonideal Magnetohydrodynamic Effects

Linking planetesimal and dust content in protoplanetary disks via a local toy model

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