Forming Planetesimals in Solar and Extrasolar Nebulae

Abstract

Planets are built from planetesimals: solids larger than a kilometer which grow by colliding pairwise. Planetesimals themselves are unlikely to form by two-body collisions; sub-km objects have gravitational fields individually too weak, and electrostatic attraction is too feeble for growth beyond a few cm. We review the possibility that planetesimals form when self-gravity brings together vast ensembles of small particles. Even when self-gravity is weak, aerodynamic processes can accumulate solids relative to gas, paving the way for gravitational collapse. Particles pile up as they drift radially inward. Gas turbulence stirs particles, but can also seed collapse by clumping them. While the feedback of solids on gas triggers vertical shear instabilities that obstruct self-gravity, this same feedback triggers streaming instabilities that strongly concentrate particles. Numerical simulations find that solids 10-100 cm in size gravitationally collapse in turbulent disks. We outline areas for progress, including the possibility that still smaller objects self-gravitate.

To appear in Annual Reviews. This review is intended to be both current and pedagogical. Incorporates suggestions from the community; further comments welcome. v2: Single-spaced

References in corpus (21)

• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? I. Mapping the zoo of laboratory collision experiments
• Asteroids Were Born Big
• Closed-form expressions for particle relative velocities induced by turbulence
• Particle Clumping and Planetesimal Formation Depend Strongly on Metallicity
• Towards planetesimals: dense chondrule clumps in the protoplanetary nebula
• A Spitzer view of protoplanetary disks in the gamma Velorum cluster
• Dust coagulation in protoplanetary disks: porosity matters
• Heat and Dust in Active Layers of Protostellar Disks
• Why Do T Tauri Disks Accrete?
• Dust sedimentation and self-sustained Kelvin-Helmholtz turbulence in protoplanetary disk mid-planes. I. Radially symmetric simulations
• Turbulent Torques on Protoplanets in a Dead Zone
• Midplane sedimentation of large solid bodies in turbulent protoplanetary discs
• Vertical Shearing Instabilities in Radially Shearing Disks: The Dustiest Layers of the Protoplanetary Nebula
• Mass accretion rates in self-regulated disks of T Tauri stars
• Three-Dimensional Simulations of Kelvin-Helmholtz Instability in Settled Dust Layers in Protoplanetary Disks
• $N$-body Simulation of Planetesimal Formation Through Gravitational Instability of a Dust Layer
• Formation, Survival, and Destruction of Vortices in Accretion Disks
• Models of the Structure and Evolution of Protoplanetary Disks
• Dust in Proto-Planetary Disks: Properties and Evolution
• Multi-Wavelength Imaging of Young Stellar Object Disks: Toward an Understanding of Disk Structure and Dust Evolution

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