On the non-axisymmetric fragmentation of rings generated by the Secular Gravitational Instability

Abstract

Ringed structures have been observed in a variety of protoplanetary discs. Among the processes that might be able to generate such features, the Secular Gravitational Instability (SGI) is a possible candidate. It has also been proposed that the SGI might lead to the formation of planetesimals during the non-linear phase of the instability. In this context, we employ two-fluid hydrodynamical simulations with self-gravity to study the non-axisymmetric, non-linear evolution of ringed perturbations that grow under the action of the SGI. We find that the non-linear evolution outcome of the SGI depends mainly on the initial linear growth rate. For SGI growth rates smaller than typically $\sigma \gtrsim 10^{-4}-10^{-5}\Omega$, dissipation resulting from dust feedback introduces a $m=1$ spiral wave in the gas, even for Toomre gas stability parameters $Q_g>2$ for which non-axisymmetric instabilities appear in a purely gaseous disc. This one-armed spiral subsequently traps dust particles until a dust-to-gas ratio $\epsilon \sim 1$ is achieved. For higher linear growth rates, the dust ring is found to undergo gravitational collapse until the bump in the surface density profile becomes strong enough to trigger the formation of dusty vortices through the Rossby Wave Instability (RWI). Enhancements in dust density resulting from this process are found to scale with the linear growth rate, and can be such that the dust density is higher than the Roche density, leading to the formation of bound clumps. Fragmentation of axisymmetric rings produced by the SGI might therefore appear as a possible process for the formation of planetesimals.

accepted in MNRAS

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Cited by in corpus (12)

• Effects of Dust Evolution on the Vertical Shear Instability in the Outer Regions of Protoplanetary Disks
• Coagulation Instability in Protoplanetary Disks: A Novel Mechanism Connecting Collisional Growth and Hydrodynamical Clumping of Dust Particles
• Two saturated states of the vertical shear instability in protoplanetary disks with vertically varying cooling times
• Streaming instabilities in accreting and magnetized laminar protoplanetary disks
• 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
• Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks I: First Numerical Study of Accelerated Dust Growth and Dust Concentration at Outer Radii
• Substructures in protoplanetary disks imprinted by compact planetary systems
• On the evolution of pebble-accreting planets in evolving protoplanetary discs
• Stability of Dusty Rings in Protoplanetary Discs
• Planetesimal Growth in Evolving Protoplanetary Disks: Constraints from the Pebble Supply
• Planetesimal formation by the gravitational instability of dust ring structures