The growth of super-Earths: the importance of a self-consistent treatment of disc structures and pebble accretion

Abstract

The conditions in the protoplanetary disc are determinant for the various planet formation mechanisms. We present a framework which combines self-consistent disc structures with the calculations of the growth rates of planetary embryos via pebble accretion, in order to study the formation of Super-Earths. We first perform 2D hydrodynamical simulations of the inner discs, considering a grain size distribution with multiple chemical species and their corresponding size and composition dependent opacities. The resulting aspect ratios are almost constant with orbital distance, resulting in radially constant pebble isolation masses, the mass where pebble accretion stops. This supports the "peas-in-a-pod" constraint from the Kepler observations. The derived pebble sizes are used to calculate the growth rates of planetary embryos via pebble accretion. Discs with low levels of turbulence (expressed through the $\alpha$-viscosity) and/or high dust fragmentation velocities allow larger particles, hence lead to smaller pebble isolation masses, and the contrary. At the same time, small pebble sizes lead to low accretion rates. We find that there is a trade-off between the pebble isolation mass and the growth timescale with the best set of parameters being an $\alpha$-viscosity of $10^{-3}$ and a dust fragmentation velocity of 10 m/s, mainly for an initial gas surface density (at 1 AU) greater than 1000 $g/c{\mathrm{m}}^2$. A self-consistent treatment between the disc structures and the pebble sizes is thus of crucial importance for planet formation simulations.

arXiv commentAccepted by A&A, 15 pages, 13 figures

References in corpus (70)

• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Streaming Instabilities in Protoplanetary Disks
• The false positive rate of Kepler and the occurrence of planets
• Planetary Candidates Observed by Kepler, III: Analysis of the First 16 Months of Data
• Using FU Orionis Outbursts to Constrain Self-Regulated Protostellar Disk Models
• Rapid growth of gas-giant cores by pebble accretion
• A simple model for the evolution of the dust population in protoplanetary disks
• Prevalence of Earth-size planets orbiting Sun-like stars
• Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
• Gas- and dust evolution in protoplanetary disks
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• The effect of gas drag on the growth of protoplanets -- Analytical expressions for the accretion of small bodies in laminar disks
• Growth Model Interpretation of Planet Size Distribution
• The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? II. Introducing the bouncing barrier
• Flaring vs. self-shadowed disks: the SEDs of Herbig Ae/Be stars
• Protoplanetary Disk Turbulence Driven by the Streaming Instability: Non-Linear Saturation and Particle Concentration
• Forming the cores of giant planets from the radial pebble flux in protoplanetary discs
• Separating gas-giant and ice-giant planets by halting pebble accretion
• Forming Planetesimals in Solar and Extrasolar Nebulae
• Breaking the Chains: Hot Super-Earth systems from migration and disruption of compact resonant chains
• The stickiness of micrometer-sized water-ice particles
• Protoplanetary Disk Turbulence Driven by the Streaming Instability: Linear Evolution and Numerical Methods
• Pebble isolation mass --- scaling law and implications for the formation of super-Earths and gas giants
• The structure of protoplanetary discs around evolving young stars
• Halting Type I planet migration in non-isothermal disks
• Planetesimal formation starts at the snow line
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• The great dichotomy of the Solar System: small terrestrial embryos and massive giant planet cores
• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
• Dust size distributions in coagulation/fragmentation equilibrium: Numerical solutions and analytical fits
• Planetesimal formation near the snowline: in or out?
• The Exoplanet Population Observation Simulator. I - The Inner Edges of Planetary Systems
• Dynamics of pebbles in the vicinity of a growing planetary embryo: hydro-dynamical simulations
• The Nature of the Radius Valley: Hints from Formation and Evolution Models
• Evolution of Protoplanetary Discs with Magnetically Driven Disc Winds
• Fast accretion of small planetesimals by protoplanetary cores
• Magneto-thermal Disk Wind from Protoplanetary Disks
• The gas temperature in the surface layers of protoplanetary disks
• Contacts of Water Ice in Protoplanetary Disks - Laboratory Experiments
• N-body simulations of planetary accretion around M dwarf stars
• Modeling the Formation of Giant Planet Cores I: Evaluating Key Processes
• Formation of TRAPPIST-1 and other compact systems
• Kepler Multi-Planet Systems Exhibit Unexpected Intra-system Uniformity in Mass and Radius
• The radial dependence of pebble accretion rates: A source of diversity in planetary systems I. Analytical formulation
• Reduced gas accretion on super-Earths and ice giants
• Survival of the mm-cm size grain population observed in protoplanetary disks
• Hot super-Earths and giant planet cores from different migration histories
• Planet formation models: the interplay with the planetesimal disc
• Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line
• Mass and Mass Scalings of Super-Earths
• How much does turbulence change the pebble isolation mass for planet formation?
• Hydrodynamics of embedded planets' first atmospheres - III. The role of radiation transport for super-Earth planets
• Migration-driven diversity of super-Earth compositions
• Including Dust Coagulation in Hydrodynamic Models of Protoplanetary Disks: Dust Evolution in the Vicinity of a Jupiter-mass Planet
• Formation of close-in super-Earths in evolving protoplanetary disks due to disk winds
• The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? III. Sedimentation driven coagulation inside the snow-line
• Rocky super-Earths or waterworlds: the interplay of planet migration, pebble accretion and disc evolution
• Influence of sub- and super-solar metallicities on the compositions of solid planetary building blocks
• Pebble-driven planet formation for TRAPPIST-1 and other compact systems
• Planetary Core Formation with Collisional Fragmentation and Atmosphere to Form Gas Giant Planets
• The Solar System as an Exoplanetary System
• The California-Kepler Survey. VI: Kepler Multis and Singles Have Similar Planet and Stellar Properties Indicating a Common Origin
• Effect of nucleation on icy pebble growth in protoplanetary discs
• Most super-Earths formed by dry pebble accretion are less massive than 5 Earth masses
• Influence of viscosity and the adiabatic index on planetary migration
• Exploring the conditions for forming cold gas giants through planetesimal accretion
• Influence of grain growth on the thermal structure of protoplanetary discs
• Inner rocky super-Earth formation: distinguishing the formation pathways in viscously heated and passive discs

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