New growth mechanism of dust grains in protoplanetary disks with magnetically driven disk winds

Abstract

We discovered a new growth mode of dust grains to km-sized bodies in protoplanetary disks that evolve by viscous accretion and magnetically driven disk winds (MDWs). We solved an approximate coagulation equation of dust grains with time-evolving disks that consist of both gas and solid components by a one-dimensional model. With the grain growth, all solid particles initially drift inward toward the central star by the gas drag force. However, the radial profile of gas pressure, $P$, is modified by the MDW that disperses the gas in an inside-out manner. Consequently, a local concentration of solid particles is created by the converging radial flux of drifting dust grains at the location with the convex upward profile of $P$. When the dimensionless stopping time, $\mathrm{St}$, there exceeds unity, the solid particles spontaneously reach the growth dominated state because of the positive feedback between the suppressed radial drift and the enhanced accumulation of dust particles that drift from the outer part. Once the solid particles are in the drift limited state, the above-mentioned condition of $\mathrm{St}\gtrsim 1$ for the dust growth is equivalent with \begin{equation} Σ_{\rm d}/Σ_{\rm g}\gtrsim η, \nonumber \end{equation} where ${\Sigma }_{\mathrm{d}}/{\Sigma }_{\mathrm{g}}$ is the dust-to-gas surface-density ratio and $\eta$ is dimensionless radial pressure-gradient force. As a consequence of the successful growth of dust grains, a ring-like structure containing planetesimal-sized bodies is formed at the inner part of the protoplanetary disks. Such a ring-shaped concentration of planetesimals is expected to play a vital role in the subsequent planet formation.

24 pages, 10 figures, 1 table, accepted for publication in The Astrophysical Journal

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Cited by in corpus (13)

• JWST/NIRSpec Reveals the Nested Morphology of Disk Winds from Young Stars
• Collisional Growth and Fragmentation of Dust Aggregates with Low Mass Ratios. I: Critical Collision Velocity for Water Ice
• Distant formation and differentiation of outer main belt asteroids and carbonaceous chondrite parent bodies
• Coagulation Instability in Protoplanetary Disks: A Novel Mechanism Connecting Collisional Growth and Hydrodynamical Clumping of Dust Particles
• Formation of pebbles in (gravito-)viscous protoplanetary disks with various turbulent strengths
• Effective dust growth in laminar circumplanetary discs with magnetic wind-driven accretion
• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks II: Dust Ring Formation Mediated by Backreaction and Fragmentation
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• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks I: First Numerical Study of Accelerated Dust Growth and Dust Concentration at Outer Radii
• Planetesimal formation at the gas pressure bump following a migrating planet II. Effects of dust growth
• Modelling the secular evolution of proto-planetary disc dust sizes -- A comparison between the viscous and magnetic wind case
• Early Initiation of Inner Solar System Formation at Dead-Zone Inner Edge
• On the crystallinity of silicate dust in evolving protoplanetary disks due to magnetically driven disk winds