Global drag-induced instabilities in protoplanetary disks

Abstract

We use the Fokker-Planck equation and model the dispersive dynamics of solid particles in annular protoplanetary disks whose gas component is more massive than the particle phase. We model particle--gas interactions as hard sphere collisions, determine the functional form of diffusion coefficients, and show the existence of two global unstable modes in the particle phase. These modes have spiral patterns with the azimuthal wavenumber $m=1$ and rotate slowly. We show that in ring-shaped disks, the phase space density of solid particles increases linearly in time towards an accumulation point near the location of pressure maximum, while instabilities grow exponentially. Therefore, planetesimals and planetary cores can be efficiently produced near the peaks of unstable density waves. In this mechanism, particles migrating towards the accumulation point will not participate in the formation of planets, and should eventually form a debris ring like the main asteroid belt or classical Kuiper belt objects. We present the implications of global instabilities to the formation of ice giants and terrestrial planets in the solar system.

11 pages, 5 Figures, 2 Tables, accepted for publication in the Astrophysical Journal (revised version with applications to planet formation in the solar system)

References in corpus (3)

• Direct Imaging of Fine Structures in Giant Planet Forming Regions of the Protoplanetary Disk around AB Aurigae
• On the dynamics of planetesimals embedded in turbulent protoplanetary discs with dead zones
• Unstable Disk Galaxies. I. Modal Properties

Cited by in corpus (9)

• The Fundamentally Different Dynamics of Dust and Gas in Molecular Clouds
• The Dynamics of Charged Dust in Magnetized Molecular Clouds
• Jumping the Gap: The Formation Conditions and Mass Function of Pebble-Pile Planetesimals
• The Resonant Drag Instability (RDI): Acoustic Modes
• Some Stars are Totally Metal: A New Mechanism Driving Dust Across Star-Forming Clouds, and Consequences for Planets, Stars, and Galaxies
• A Simple Phenomenological Model for Grain Clustering in Turbulence
• Are the Formation and Abundances of Metal-Poor Stars the Result of Dust Dynamics?
• Modal analysis of gravitational instabilities in nearly Keplerian, counter-rotating collisionless discs
• Drag-driven instability of a dust layer in a magnetized protoplanetary disc