Pebble Accretion in Turbulent Protoplanetary Disks

Abstract

It has been realized in recent years that the accretion of pebble-sized dust particles onto planetary cores is an important mode of core growth, which enables the formation of giant planets at large distances and assists planet formation in general. The pebble accretion theory is built upon the orbit theory of dust particles in a laminar protoplanetary disk (PPD). For sufficiently large core mass (in the "Hill regime"), essentially all particles of appropriate sizes entering the Hill sphere can be captured. However, the outer regions of PPDs are expected to be weakly turbulent due to the magnetorotational instability (MRI), where turbulent stirring of particle orbits may affect the efficiency of pebble accretion. We conduct shearing-box simulations of pebble accretion with different levels of MRI turbulence (strongly turbulent assuming ideal magnetohydrodynamics, weakly turbulent in the presence of ambipolar diffusion, and laminar) and different core masses to test the efficiency of pebble accretion at a microphysical level. We find that accretion remains efficient for marginally coupled particles (dimensionless stopping time tau_s ~ 0.1 - 1) even in the presence of strong MRI turbulence. Though more dust particles are brought toward the core by the turbulence, this effect is largely canceled by a reduction in accretion probability. As a result, the overall effect of turbulence on the accretion rate is mainly reflected in the changes in the thickness of the dust layer. On the other hand, we find that the efficiency of pebble accretion for strongly coupled particles (down to tau_s ~ 0.01) can be modestly reduced by strong turbulence for low-mass cores.

15 pages, 7 figures, accepted for publication in ApJ

References in corpus (14)

• Athena: A New Code for Astrophysical MHD
• Optical Images of an Exosolar Planet 25 Light Years from Earth
• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• Separating gas-giant and ice-giant planets by halting pebble accretion
• Dust size distributions in coagulation/fragmentation equilibrium: Numerical solutions and analytical fits
• Magnetic fields in protoplanetary disks
• Formation of Jupiter using opacities based on detailed grain physics
• Hydrodynamics of Embedded Planets' First Atmospheres. II. A Rapid Recycling of Atmospheric Gas
• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: II. Full 3D Simulations toward the Outer Disk
• Magnetic Flux Concentration and Zonal Flows in Magnetorotational Instability Turbulence
• Minimum Core Masses for Giant Planet Formation With Realistic Equations of State and Opacities
• Rapid Formation of Icy Super-Earths and the Cores of Gas Giant Planets
• Dust Transport in MRI Turbulent Disks: Ideal and Non-ideal MHD with Ambipolar Diffusion
• Challenges in Forming the Solar System's Giant Planet Cores via Pebble Accretion

Cited by in corpus (9)

• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• Including Dust Coagulation in Hydrodynamic Models of Protoplanetary Disks: Dust Evolution in the Vicinity of a Jupiter-mass Planet
• Ring formation and dust dynamics in wind-driven protoplanetary discs: global simulations
• A Tale of Planet Formation: From Dust to Planets
• Efficient planet formation by pebble accretion in ALMA rings
• Turbulent Dust-trapping Rings as Efficient Sites for Planetesimal Formation
• Vertical evolution of exocometary gas: I. How vertical diffusion shortens the CO lifetime
• Influences of three-dimensional gas flow induced by protoplanets on pebble accretion --$\mathrm{I}$. shear regime
• Effect of Different Angular Momentum Transport mechanisms on the Distribution of Water in Protoplanetary Disks