A coagulation-fragmentation model for the turbulent growth and destruction of preplanetesimals

Abstract

To treat the problem of growing protoplanetary disc solids across the meter barrier, we consider a very simplified two-component coagulation-fragmentation model that consists of macroscopic boulders and smaller dust grains, the latter being the result of catastrophic collisions between the boulders. Boulders in turn increase their radii by sweeping up the dust fragments. An analytical solution to the dynamical equations predicts that growth by coagulation-fragmentation can be efficient and allow agglomeration of 10-meter-sized objects within the time-scale of the radial drift. These results are supported by computer simulations of the motion of boulders and fragments in 3-D time-dependent magnetorotational turbulence. Allowing however the fragments to diffuse freely out of the sedimentary layer of boulders reduces the density of both boulders and fragments in the mid-plane, and thus also the growth of the boulder radius, drastically. The reason is that the turbulent diffusion time-scale is so much shorter than the collisional time-scale that dust fragments leak out of the mid-plane layer before they can be swept up by the boulders there. Our conclusion that coagulation-fragmentation is not an efficient way to grow across the meter barrier in fully turbulent protoplanetary discs confirms recent results by Brauer, Dullemond, & Henning who solved the coagulation equation in a parameterised turbulence model with collisional fragmentation, cratering, radial drift, and a range of particle sizes. We find that a relatively small population of boulders in a sedimentary mid-plane layer can populate the entire vertical extent of the disc with small grains and that these grains are not first generation dust, but have been through several agglomeration-destruction cycles during the simulations.

arXiv comment17 pages, 8 figures. Accepted for publication in A&A

References in corpus (30)

• Rapid planetesimal formation in turbulent circumstellar discs
• Streaming Instabilities in Protoplanetary Disks
• Nonlinear Outcome of Gravitational Instability in Cooling, Gaseous Disks
• Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
• Dust coagulation in protoplanetary disks: a rapid depletion of small grains
• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• Radial Flow of Dust Particles in Accretion Disks
• The effect of dust settling on the appearance of protoplanetary disks
• Turbulence in Accretion Disks. Vorticity Generation and Angular Momentum Transport via the Global Baroclinic Instability
• Magnetorotational Instability in Protoplanetary Disks. II. Ionization State and Unstable Regions
• The locality of transport in self-gravitating accretion discs
• On the Dynamical Foundations of Alpha Disks
• Protoplanetary Disk Turbulence Driven by the Streaming Instability: Linear Evolution and Numerical Methods
• Large dust particles in disks around T Tauri stars
• Large grains in the disk of CQ Tau
• Accelerated planetesimal growth in self-gravitating protoplanetary discs
• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• Survival of the mm-cm size grain population observed in protoplanetary disks
• VLA Imaging of the Disk Surrounding the Nearby Young Star TW Hya
• Reduction of chemical networks. II. Analysis of the fractional ionisation in protoplanetary discs
• Binarity as a key factor in protoplanetary disk evolution: Spitzer disk census of the eta Chamaeleontis cluster
• On the accumulation of solid bodies in global turbulent protoplanetary disc models
• Investigating grain growth in disks around southern T Tauri stars at millimetre wavelengths
• Turbulent Torques on Protoplanets in a Dead Zone
• Computational aspects of astrophysical MHD and turbulence
• Midplane sedimentation of large solid bodies in turbulent protoplanetary discs
• Spatially Resolving the Inner Disk of TW Hya
• Collisions between equal sized ice grain agglomerates
• Early dust evolution in protostellar accretion disks
• Dust Stratification in Young Circumstellar Disks

Cited by in corpus (28)

• Zonal Flows and Long-Lived Axisymmetric Pressure Bumps in Magnetorotational Turbulence
• How to form planetesimals from mm-sized chondrules and chondrule aggregates
• Planetesimal formation by sweep-up: How the bouncing barrier can be beneficial to growth
• Planet formation bursts at the borders of the dead zone in 2D numerical simulations of circumstellar disks
• Numerical Modeling of the Coagulation and Porosity Evolution of Dust Aggregates
• Standing on the shoulders of giants: Trojan Earths and vortex trapping in low mass self-gravitating protoplanetary disks of gas and solids
• Modeling Magnetorotational Turbulence in Protoplanetary Disks with Dead Zones
• High-resolution simulations of planetesimal formation in turbulent protoplanetary discs
• From dust to planetesimals: an improved model for collisional growth in protoplanetary disks
• Stellar Mass Dependent Disk Dispersal
• High Velocity Dust Collisions: Forming Planetesimals in a Fragmentation Cascade with Final Accretion
• Embryos grown in the dead zone: Assembling the first protoplanetary cores in low mass self-gravitating circumstellar disks of gas and solids
• The structure of the protoplanetary disk surrounding three young intermediate mass stars. II. Spatially resolved dust and gas distribution
• Volatile depletion in the TW Hydrae disk atmosphere
• A Spitzer Survey of Protoplanetary Disk Dust in the Young Serpens Cloud: How do Dust Characteristics Evolve with Time?
• Dust growth in protoplanetary disks - a comprehensive experimental/theoretical approach
• Planetesimal Formation in Magnetorotationally Dead Zones: Critical Dependence on the Net Vertical Magnetic Flux
• The physics of protoplanetesimal dust agglomerates. VII The low-velocity collision behavior of large dust agglomerates
• Rapid Evolution of the Innermost Dust Disk of Protoplanetary Disks Surrounding Intermediate-mass Stars
• From Dust To Planetesimal: The Snowball Phase ?
• Impact Angle Influence in High Velocity Dust Collisions during Planetesimal Formation
• Planet Formation In Highly Inclined Binary Systems I. Planetesimals Jump Inwards And Pile Up
• The Fate of Planetesimals in Turbulent Disks with Dead Zones. I. The Turbulent Stirring Recipe
• The Formation and Dynamics of Super-Earth Planets
• Forming Different Planetary Systems
• Phyllosilicate Emission from Protoplanetary Disks: Is the Indirect Detection of Extrasolar Water Possible?
• Size and density sorting of dust grains in SPH simulations of protoplanetary disc II: Fragmentation
• A fast tree algorithm for multi-component coagulation equation