Planetesimal formation by an axisymmetric radial bump of the column density of the gas in a protoplanetary disk

Onishi, Isamu K.; Sekiya, Minoru

doi:10.1186/s40623-017-0637-z

Cited by 22 publications

(19 citation statements)

References 31 publications

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“…Some key limitations of this work include the omission of stellar vertical gravity, particle self-gravity, and an azimuthal component to the simulations. Onishi & Sekiya (2017) corrected the first problem with a new 2D simulation that included vertical gravity. Because they allow dust particles to sediment, they found that the back-reaction is only a significant force in the thin dust layer at the midplane, where the particle density is high, and the majority of the pressure bump is largely unaffected.…”

Section: Introductionmentioning

confidence: 99%

Protoplanetary Disk Rings as Sites for Planetesimal Formation

Carrera

Simon

et al. 2021

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Axisymmetric dust rings are a ubiquitous feature of young protoplanetary disks. These rings are likely caused by pressure bumps in the gas profile; a small bump can induce a traffic-jam-like pattern in the dust density, while a large bump may halt radial dust drift entirely. The resulting increase in dust concentration may trigger planetesimal formation by the streaming instability (SI), as the SI itself requires some initial concentration of dust. Here we present the first 3D simulations of planetesimal formation in the presence of a pressure bump modeled specifically after those seen by Atacama Large Millimeter/submillimeter Array. We place a pressure bump at the center of a large 3D shearing box, along with an initial solid-to-gas ratio of Z = 0.01, and we include both particle back-reaction and particle self-gravity. We consider millimeter-sized and centimeter-sized particles separately. For simulations with centimeter-sized particles, we find that even a small pressure bump leads to the formation of planetesimals via the SI; a pressure bump does not need to fully halt radial particle drift for the SI to become efficient. Furthermore, pure gravitational collapse via concentration in pressure bumps (such as would occur at sufficiently high concentrations and without the SI) is not responsible for planetesimal formation. For millimeter-sized particles, we find tentative evidence that planetesimal formation does not occur. If this result is confirmed at higher resolution, it could put strong constraints on where planetesimals can form. Ultimately, our results show that for centimeter-sized particles planetesimal formation in pressure bumps is extremely robust.

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Section: Introductionmentioning

confidence: 99%

Protoplanetary Disk Rings as Sites for Planetesimal Formation

Carrera

Simon

et al. 2021

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“…Previous works that investigated the evolution of dust in the vicinity of a pressure bump ( Taki et al (2016); Onishi and Sekiya (2017); Huang et al (2020); Carrera et al (021a)) did not report unstable behavior of dust rings that formed at a pressure bump, as described in the previous sections. Although Taki et al (2016) found that the pressure bump gets destroyed by the particle feedback within hundreds of orbital periods without sufficient reforcing, this turned out to be caused by the neglect of vertical stellar gravity and hence dust sedimentation in the midplane (Onishi and Sekiya 2017). Also, for the parameters used by Taki et al (2016) (Z = 0.1, τ 0 = 1) or Huang et al (2020) Fig.…”

Section: Discussionmentioning

confidence: 68%

“…One therefore assumes that additional processes are required to trigger the SI. Among these processes are particle concentration in zonal flows (Johansen et al 009b), pressure bumps (Haghighipour and Boss 003a,b;Taki et al 2016;Onishi and Sekiya 2017;Huang et al 2020), vortices (Barge andSommeria 1995;Johansen et al 2004;Klahr and Bodenheimer 2006;Fu et al 2014;Crnkovic-Rubsamen et al 2015;Raettig et al 2015;Miranda et al 2017;Surville and Mayer 2019), or other instabilities such as the Dust Settling Instability (DSI: Squire and Hopkins (2018); Krapp et al (2020)).…”

Section: Introductionmentioning

confidence: 99%

Impact of Local Pressure Enhancements on Dust Concentration inTurbulent Protoplanetary Discs

Lehmann,

Lin

2021

Preprint

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The standard core accretion model for planetesimal formation in protoplanetary discs (PPDs) is known to bear a number of challenges. One is the vertical settling of dust to the disc mid-plane against turbulent stirring. This is particularly relevant in presence of the vertical shear instability (VSI), a purely hydrodynamic instability applicable to the outer parts of PPDs, which drives moderate turbulence characterized by large-scale vertical motions. We investigate the evolution of dust and gas in the vicinity of local pressure enhancements (pressure bumps) in a PPD with turbulence sustained by the VSI. Our goal is to determine the morphology of dust concentrations and if dust can concentrate sufficiently to reach conditions that can trigger the Streaming Instability (SI). We perform a suite of global 2D axisymmetric and 3D simulations of dust and gas for a range of values for Σ d /Σ g (ratio of dust-to-gas surface mass densities or metallicity), particle Stokes numbers τ, and pressure bump amplitude A. Dust feedback onto the gas is included. For the first time we demonstrate in global 3D simulations the collection of dust in long-lived vortices induced by the VSI. These vortices, which undergo slow radial inward drift, are the dusty analogs of large long-lived vortices found in previous dust-free simulations of the VSI. Without a pressure bump and for solar metallicity Z ≈ 0.01 and Stokes numbers τ ∼ 10 −2 we find that such vortices can reach dust-to-gas density ratios slightly below unity in the discs' mid-plane, while for Z 0.05 long-lived vortices are largely absent. In the presence of a pressure bump, for Z ≈ 0.01 and τ ∼ 10 −2 a dusty vortex forms that reaches dust-to-gas ratios of a few times unity, such that the SI is expected to develop, before it eventually shears out into a turbulent dust ring. At intermediate metallicities Z ∼ 0.03 this occurs for τ ∼ 5 • 10 −3 , but with a weaker and more short-lived vortex, while for larger τ only a turbulent dust ring forms. For Z 0.03 we find that the dust ring becomes increasingly axisymmetric for increasing τ and dust-to-gas ratios reach order unity for τ 5 • 10 −3 . Furthermore, the vertical mass flow profile of the disc is strongly affected by dust for Z 0.03, such that gas is transported inward near the mid-plane and outward at larger heights, which is the reversed situation compared to simulations with zero or small amounts of dust. We find Reynolds stresses or α-values to drop moderately as ∼ 10 −3 − 10 −4 for metallicities increasing as Z = 0 − 0.05. Our results suggest that the VSI can play an active role in the formation of planetesimals through the formation of vortices for plausible values of metallicity and particle size. Also it may provide a natural explanation for the presence or absence of asymmetries of observed dust rings in PPDs, depending on the background metallicity.

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“…This is still justified since our particles are too small (St < 10 −3 ) to cause any perturbation beyond slowing down the concentration process and we can be infer it also by studying the single dust species scenario described in the Appendix A.1. Studies of Onishi & Sekiya (2017) also showed that the back-reaction still allows the dust to accumulate at pressure maxima, and that the dust traps do not self-destruct by this effect when taking into account the vertical distribution of solids. For the reactivation phase we implement the gas velocities as described by equations Eq.…”

Section: Simulation With Dust Back-reactionmentioning

confidence: 99%

The Dimming of RW Auriga: Is Dust Accretion Preceding an Outburst?

Gárate

Birnstiel²,

Stammler³

et al. 2019

ApJ

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RW Aur A has experienced various dimming events in the last years, decreasing its brightness by ∼ 2 mag for periods of months to years. Multiple observations indicate that a high concentration of dust grains, from the protoplanetary disk's inner regions, is blocking the starlight during these events. We propose a new mechanism that can send large amounts of dust close to the star on short timescales, through the reactivation of a dead zone in the protoplanetary disk. Using numerical simulations we model the accretion of gas and dust, along with the growth and fragmentation of particles in this scenario. We find that after the reactivation of the dead zone, the accumulated dust is rapidly accreted towards the star in around 15 years, at rates ofṀ d = 6 × 10 −6 M /yr and reaching dust-to-gas ratios of ≈ 5, preceding an increase in the gas accretion by a few years. This sudden rise of dust accretion can provide the material required for the dimmings, although the question of how to put the dust into the line of sight remains open to speculation.

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Planetesimal formation by an axisymmetric radial bump of the column density of the gas in a protoplanetary disk

Cited by 22 publications

References 31 publications

Protoplanetary Disk Rings as Sites for Planetesimal Formation

Protoplanetary Disk Rings as Sites for Planetesimal Formation

Impact of Local Pressure Enhancements on Dust Concentration inTurbulent Protoplanetary Discs

The Dimming of RW Auriga: Is Dust Accretion Preceding an Outburst?

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