Coagulation Instability in Protoplanetary Disks: A Novel Mechanism Connecting Collisional Growth and Hydrodynamical Clumping of Dust Particles

Abstract

We present a new instability driven by a combination of coagulation and radial drift of dust particles. We refer to this instability as ``coagulation instability" and regard it as a promising mechanism to concentrate dust particles and assist planetesimal formation in the very early stages of disk evolution. Because of dust-density dependence of collisional coagulation efficiency, dust particles efficiently (inefficiently) grow in a region of positive (negative) dust density perturbations, which lead to a small radial variation of dust sizes and as a result radial velocity perturbations. The resultant velocity perturbations lead to dust concentration and amplify dust density perturbations. This positive feedback makes a disk unstable. The growth timescale of coagulation instability is a few tens of orbital periods even when dust-to-gas mass ratio is of the order of $10^{-3}$. In a protoplanetary disk, radial drift and coagulation of dust particles tend to result in dust depletion. The present instability locally concentrates dust particles even in such a dust-depleted region. The resulting concentration provides preferable sites for dust-gas instabilities to develop, which leads to further concentration. Dust diffusion and aerodynamical feedback tend to stabilize short-wavelength modes, but do not completely suppress the growth of coagulation instability. Therefore, coagulation instability is expected to play an important role in setting up the next stage for other instabilities to further develop toward planetesimal formation, such as streaming instability or secular gravitational instability.

31 pages, 15 figures, accepted for publication in ApJ

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Cited by in corpus (11)

• An Analytical Theory for the Growth from Planetesimals to Planets by Polydisperse Pebble Accretion
• Formation of dust clumps with sub-Jupiter mass and cold shadowed region in gravitationally unstable disk around Class 0/I protostar in L1527 IRS
• Mixing is easy: New insights for cosmochemical evolution from pre-stellar core collapse
• No evidence of the significant grain growth but tentative discovery of disk substructure in a disk around the Class I Protostar L1489 IRS
• Investigating the Bouncing Barrier with Collision Simulations of Compressed Dust Aggregates
• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks II: Dust Ring Formation Mediated by Backreaction and Fragmentation
• On Secular Gravitational Instability in Vertically Stratified Disks
• Dust grain shattering in protoplanetary discs: collisional fragmentation or rotational disruption?
• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks I: First Numerical Study of Accelerated Dust Growth and Dust Concentration at Outer Radii
• Planetesimal Growth in Evolving Protoplanetary Disks: Constraints from the Pebble Supply
• Magnetic clumping of charged dust in the dense interstellar medium