Hydrodynamical turbulence in eccentric circumbinary discs and its impact on the in situ formation of circumbinary planets

Abstract

Eccentric gaseous discs are unstable to a parametric instability involving the resonant interaction between inertial-gravity waves and the eccentric mode in the disc. We present 3D global hydrodynamical simulations of inviscid circumbinary discs that form an inner cavity and become eccentric through interaction with the central binary. The parametric instability grows and generates turbulence that transports angular momentum with stress parameter $\alpha \sim 5\times 10^{-3}$ at distances $\lesssim 7a_{bin}$, where $a_{bin}$ is the binary semi-major axis. Vertical turbulent diffusion occurs at a rate corresponding to ${\alpha }_{diff}\sim 1-2\times 10^{-3}$. We examine the impact of turbulent diffusion on the vertical settling of pebbles, and on the rate of pebble accretion by embedded planets. In steady state, dust particles with Stokes numbers $St\lesssim 0.1$ form a layer of finite thickness $H_d\gtrsim 0.1H$, where $H$ is the gas scale height. Pebble accretion efficiency is then reduced by a factor $r_{acc}/H_d$, where $r_{acc}$ is the accretion radius, compared to the rate in a laminar disc. For accreting core masses with $m_p\lesssim 0.1M_{\oplus }$, pebble accretion for particles with $St\gtrsim 0.5$ is also reduced because of velocity kicks induced by the turbulence. These effects combine to make the time needed by a Ceres-mass object to grow to the pebble isolation mass, when significant gas accretion can occur, longer than typical disc lifetimes. Hence, the origins of circumbinary planets orbiting close to their central binary systems, as discovered by the Kepler mission, are difficult to explain using an in situ model that invokes a combination of the streaming instability and pebble accretion.

Accepted in MNRAS

References in corpus (27)

• Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations
• The Transiting Circumbinary Planets Kepler-34 and Kepler-35
• Separating gas-giant and ice-giant planets by halting pebble accretion
• Global simulations of protoplanetary disks with ohmic resistivity and ambipolar diffusion
• How to form planetesimals from mm-sized chondrules and chondrule aggregates
• Viscous Hydrodynamics Simulations of Circumbinary Accretion Discs: Variability, Quasi-Steady State, and Angular Momentum Transfer
• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• Vertical shear instability in accretion disc models with radiation transport
• Global MHD simulations of stratified and turbulent protoplanetary discs. II. Dust settling
• Radiation Hydrodynamical Turbulence In Protoplanetary Disks: Numerical Models and Observational Constraints
• On the formation and migration of giant planets in circumbinary discs
• Relative velocities among accreting planetesimals in binary systems: the circumbinary case
• Particle dynamics in discs with turbulence generated by the vertical shear instability
• Midplane sedimentation of large solid bodies in turbulent protoplanetary discs
• On the migration of protoplanets embedded in circumbinary disks
• Co-Accretion of Chondrules and Dust in the Solar Nebula
• Dust Transport in MRI Turbulent Disks: Ideal and Non-ideal MHD with Ambipolar Diffusion
• Dust settling against hydrodynamic turbulence in protoplanetary discs
• Signatures of an eccentric disc cavity: Dust and gas in IRS 48
• On the evolution of multiple low mass planets embedded in a circumbinary disc
• The Role of Disc Self-Gravity in Circumbinary Planet Systems: I. Disc Structure and Evolution
• Hydrodynamic instability in eccentric astrophysical discs
• Planetesimal formation in self-gravitating discs: the effects of particle self-gravity and back-reaction
• Self-Destructing Spiral Waves: Global Simulations of a Spiral Wave Instability in Accretion Disks
• The Spiral Wave Instability Induced by a Giant Planet: I. Particle Stirring in the Inner Regions of Protoplanetary Disks
• Circumbinary discs with radiative cooling and embedded planets
• Properties and stability of freely propagating nonlinear density waves in accretion disks

Cited by in corpus (12)

• Parking planets in circumbinary discs
• BEBOP III. Observations and an independent mass measurement of Kepler-16 (AB) b -- the first circumbinary planet detected with radial velocities
• Dusty circumbinary discs: inner cavity structures and stopping locations of migrating planets
• Global N-body simulations of circumbinary planet formation around Kepler-16 and -34 analogues I: Exploring the pebble accretion scenario
• Vertical settling of pebbles in turbulent circumbinary discs and the in situ formation of circumbinary planets
• Dynamical structure of highly eccentric discs with applications to tidal disruption events
• Running The Gauntlet -- Survival of Small Circumbinary Planets Migrating Through Destabilising Resonances
• Terrestrial planet formation in a circumbinary disc around a coplanar binary
• Sculpting the circumbinary planet size distribution through resonant interactions with companion planets
• Importance of magnetic fields in highly eccentric discs with applications to tidal disruption events
• Parametric instability in warped astrophysical discs: growth, saturation and feedback
• On the cavity size in circumbinary discs