Grain opacity and the bulk composition of extrasolar planets. I. Results from scaling the ISM opacity

Abstract

The opacity due to grains in the envelope of a protoplanet regulates the accretion rate of gas during formation, thus the final bulk composition of planets with primordial H/He is a function of it. Observationally, for exoplanets with known mass and radius it is possible to estimate the bulk composition via internal structure models. We first determine the reduction factor of the ISM grain opacity f_opa that leads to gas accretion rates consistent with grain evolution models. We then compare the bulk composition of synthetic low-mass and giant planets at different f_opa with observations. For f_opa=1 (full ISM opacity) the synthetic low-mass planets have too small radii, i.e., too low envelope masses compared to observations. At f_opa=0.003, the value calibrated with the grain evolution models, synthetic and actual planets occupy similar mass-radius loci. The mean enrichment of giant planets relative to the host star as a function of planet mass M can be approximated as Z_p/Z_star = beta*(M/M_Jup)^alpha. We find alpha=-0.7 independent of f_opa in synthetic populations in agreement with the observational result (-0.71+-0.10). The absolute enrichment level decreases from beta=8.5 at f_opa=1 to 3.5 at f_opa=0. At f_opa=0.003 one finds beta=7.2 which is similar to the observational result (6.3+-1.0). We thus find observational hints that the opacity in protoplanetary atmospheres is much smaller than in the ISM even if the specific value of the grain opacity cannot be constrained here. The result for the enrichment of giant planets helps to distinguish core accretion and gravitational instability. In the simplest picture of core accretion where first a critical core forms and afterwards only gas is added, alpha=-1. If a core accretes all planetesimals inside the feeding zone, alpha=-2/3. The observational result lies between these values, pointing to core accretion as the formation mechanism.

arXiv comment21 pages, 15 figures. Accepted for A&A

References in corpus (71)

• The chemical composition of the Sun
• Disk Frequencies and Lifetimes in Young Clusters
• A Non-Gray Theory of Extrasolar Giant Planets and Brown Dwarfs
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• Towards a Deterministic Model of Planetary Formation I: a Desert in the Mass and Semi Major Axis Distributions of Extra Solar Planets
• Using FU Orionis Outbursts to Constrain Self-Regulated Protostellar Disk Models
• A simple model for the evolution of the dust population in protoplanetary disks
• Kepler planets: a tale of evaporation
• Models of Giant Planet formation with migration and disc evolution
• A Closely-Packed System of Low-Mass, Low-Density Planets Transiting Kepler-11
• Extrasolar planet population synthesis I: Method, formation tracks and mass-distance distribution
• Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets
• Line and Mean Opacities for Ultracool Dwarfs and Extrasolar Planets
• Timescale of Mass Accretion in Pre-Main-Sequence Stars
• How Thermal Evolution and Mass Loss Sculpt Populations of Super-Earths and Sub-Neptunes: Application to the Kepler-11 System and Beyond
• Possible Solutions to the Radius Anomalies of Transiting Giant Planets
• Extrasolar planet population synthesis IV. Correlations with disk metallicity, mass and lifetime
• A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions
• Structure and evolution of super-Earth to super-Jupiter exoplanets: I. heavy element enrichment in the interior
• The HARPS search for southern extra-solar planets XXXIV. Occurrence, mass distribution and orbital properties of super-Earths and Neptune-mass planets
• A correlation between the heavy element content of transiting extrasolar planets and the metallicity of their parent stars
• Shock Compression of Deuterium and the Interiors of Jupiter and Saturn
• Characterization of exoplanets from their formation I: Models of combined planet formation and evolution
• Atmospheres of protoplanetary cores: critical mass for nucleated instability
• Models of Jupiter's Growth Incorporating Thermal and Hydrodynamic Constraints
• Formation and Structure of Low Density Exo-Neptunes
• Characterization of exoplanets from their formation II: The planetary mass-radius relationship
• A new vision on giant planet interiors: the impact of double diffusive convection
• The Heavy Element Masses of Extrasolar Giant Planets, Revealed
• A Massive Core in Jupiter Predicted From First-Principles Simulations
• Lack of Inflated Radii for Kepler Giant Planet Candidates Receiving Modest Stellar Irradiation
• CHEOPS: A Transit Photometry Mission for ESA's Small Mission Programme
• Disk eccentricity and embedded planets
• Composition and fate of short-period super-Earths: The case of CoRoT-7b
• Critical Protoplanetary Core Masses in Protoplanetary Disks and the Formation of Short-Period Giant Planets
• Constraints on the mass of a habitable planet with water of nebular origin
• Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
• Migration and giant planet formation
• Formation of Jupiter using opacities based on detailed grain physics
• Jupiter models with improved ab initio hydrogen EOS (H-REOS.2)
• Extrasolar planet population synthesis II: Statistical comparison with observation
• Theoretical models of planetary system formation: mass vs semi-major axis
• Kepler 18-b, c, and d: A System Of Three Planets Confirmed by Transit Timing Variations, Lightcurve Validation, Spitzer Photometry and Radial Velocity Measurements
• Modeling the Formation of Giant Planet Cores I: Evaluating Key Processes
• Orbital migration of low-mass planets in evolutionary radiative models: Avoiding catastrophic infall
• The Dependence of Brown Dwarf Radii on Atmospheric Metallicity and Clouds: Theory and Comparison with Observations
• Planet formation models: the interplay with the planetesimal disc
• Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant Planets
• Grain sedimentation inside giant planet embryos
• Gas Giant Formation with Small Cores Triggered by Envelope Pollution by Icy Planetesimals
• Overabundance of alpha-elements in exoplanet host stars
• Impacts of planet migration models on planetary populations. Effects of saturation, cooling and stellar irradiation
• Deuterium Burning in Massive Giant Planets and Low-Mass Brown Dwarfs formed by Core-Nucleated Accretion
• Luminosity of young Jupiters revisited. Massive cores make hot planets
• Planetesimal Accretion onto Growing Proto-Gas-Giant Planets
• The opacity of grains in protoplanetary atmospheres
• Spin-orbit misalignment in the HD80606 planetary system
• CoRoT-10b: a giant planet in a 13.24 day eccentric orbit
• Understanding how planets become massive. I. Description and validation of a new toy model
• The Heavy Element Composition of Disk Instability Planets Can Range From Sub- to Super-Nebular
• Critical Core Masses for Gas Giant Formation with Grain-Free Envelopes
• The Effects of Metallicity, and Grain Growth and Settling on the Early Evolution of Gaseous Protoplanets
• Utilitarian Opacity Model for Aggregate Particles in Protoplanetary Nebulae and Exoplanet Atmospheres
• Deuterium burning in objects forming via the core accretion scenario - Brown dwarfs or planets?
• Infall of planetesimals onto growing giant planets: onset of runaway gas accretion and metallicity of their gas envelopes
• The composition of transiting giant extrasolar planets
• Oligarchic planetesimal accretion and giant planet formation
• Heavy Element Enrichment of a Jupiter-mass Protoplanet as a Function of Orbital Location
• The role of the initial surface density profiles of the disc on giant planet formation: comparing with observations
• An alternative look at the snowline in protoplanetary disks
• Core instability models of giant planet accretion II: forming planetary systems

Cited by in corpus (67)

• The Mass-Metallicity Relation for Giant Planets
• The imprint of exoplanet formation history on observable present-day spectra of hot Jupiters
• Planetary population synthesis coupled with atmospheric escape: a statistical view of evaporation
• Breeding Super-Earths and Birthing Super-Puffs in Transitional Disks
• Compositional imprints in density-distance-time: a rocky composition for close-in low-mass exoplanets from the location of the valley of evaporation
• Evolutionary Analysis of Gaseous Sub-Neptune-Mass Planets with MESA
• Observing transiting planets with JWST -- Prime targets and their synthetic spectral observations
• The New Generation Planetary Population Synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems
• Spectral and atmospheric characterization of 51 Eridani b using VLT/SPHERE
• How formation time-scales affect the period dependence of the transition between rocky super-Earths and gaseous sub-Neptunes and implications for ${\eta }_{\oplus }$
• The New Generation Planetary Population Synthesis (NGPPS). II. Planetary population of solar-like stars and overview of statistical results
• Global Models of Planet Formation and Evolution
• Planetary evolution with atmospheric photoevaporation I. Analytical derivation and numerical study of the evaporation valley and transition from super-Earths to sub-Neptunes
• Characterization of exoplanets from their formation III: The statistics of planetary luminosities
• Hot Jupiters: Origins, Structure, Atmospheres
• C/O and Snowline Locations in Protoplanetary Disks: The Effect of Radial Drift and Viscous Gas Accretion
• Minimum Core Masses for Giant Planet Formation With Realistic Equations of State and Opacities
• Grain opacity and the bulk composition of extrasolar planets. II. An analytical model for the grain opacity in protoplanetary atmospheres
• Two Empirical Regimes of the Planetary Mass-Radius Relation
• Planetary population synthesis
• Heavy metal rules. I. Exoplanet incidence and metallicity
• Formation, Orbital and Internal Evolutions of Young Planetary Systems
• Evolution of Gas Giant Entropy During Formation by Runaway Accretion
• Creating the Radius Gap without Mass Loss
• Jupiter's heavy-element enrichment expected from formation models
• Do Metal-Rich Stars Make Metal-Rich Planets? New Insights on Giant Planet Formation from Host Star Abundances
• Pebbles versus planetesimals: the outcomes of population synthesis models
• Planet Traps and Planetary Cores: Origins of the Planet-Metallicity Correlation
• In situ accretion of gaseous envelopes on to planetary cores embedded in evolving protoplanetary discs
• On the Formation and Chemical Composition of Super Earths
• Evidence that the Hot Jupiter WASP-77 A b Formed Beyond Its Parent Protoplanetary Disk's H2O Ice Line
• Metallicity effect and planet mass function in pebble-based planet formation models
• The TESS-Keck Survey. VIII. Confirmation of a Transiting Giant Planet on an Eccentric 261 day Orbit with the Automated Planet Finder Telescope
• Atmosphere loss in planet-planet collisions
• The Origin of Heavy Element Content Trend in Giant Planets via Core Accretion
• The mass-radius relation of intermediate-mass planets outlined by hydrodynamic escape and thermal evolution
• Two long-period transiting exoplanets on eccentric orbits: NGTS-20 b (TOI-5152 b) and TOI-5153 b
• Formation of Planetary Populations I: Metallicity & Envelope Opacity Effects
• Evolution and Magnitudes of Candidate Planet Nine
• Towards a new era in giant exoplanet characterisation
• In situ formation of hot Jupiters with companion super-Earths
• Changes in the metallicity of gas giant planets due to pebble accretion
• Planet Mass and Metallicity: The Exoplanets and Solar System Connection
• Planetary evolution with atmospheric photoevaporation II: Fitting the slope of the radius valley by combining boil-off and XUV-driven escape
• Magnetically induced termination of giant planet formation
• The interplay between pebble and planetesimal accretion in population synthesis models and its role in giant planet formation
• Giant Outer Transiting Exoplanet Mass (GOT 'EM) Survey. II. Discovery of a Failed Hot Jupiter on a 2.7 Year, Highly Eccentric Orbit
• Formation of Planetary Populations II: Effects of Initial Disk Size & Radial Dust Drift
• Blackbody Radiation from Isolated Neptunes
• Super-Earths as Failed Cores in Orbital Migration Traps
• Planet formation in the PDS 70 system: Constraining the atmospheric chemistry of PDS 70b and c
• Combined Effects of Disk Winds and Turbulence-Driven Accretion on Planet Populations
• Formation of Super-Earths by Tidally-Forced Turbulence
• Multi-modal atmospheric characterization of $\beta$ Pictoris b: Adding high-resolution continuum spectra from GRAVITY
• Connecting Planetary Composition with Formation
• The Heavy-element Content Trend of Planets: A Tracer of their Formation Sites
• Calibrated Gas Accretion and Orbital Migration of Protoplanets in 1D Disc Models
• The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b
• GEMS JWST: Transmission spectroscopy of TOI-5205b reveals significant stellar contamination and a metal-poor atmosphere
• The New Generation Planetary Population Synthesis (NGPPS). VII. Statistical comparison with the HARPS/Coralie survey
• Solid Accretion onto Neptune-Mass Planets I: In-Situ Accretion and Constraints from the metallicity of Uranus and Neptune
• Tracing bulk elemental ratios in exoplanetary atmospheres with TiO chemistry
• The influence of dust growth on the observational properties of circumplanetary discs
• The PAIRS project: a global formation model for planets in binaries. I. Effect of disc truncation on the growth of S-type planets
• Possible formation pathways for the low density Neptune-mass planet HAT-P-26b
• A Two-limb Explanation for the Optical-to-infrared Transmission Spectrum of the Hot Jupiter HAT-P-32Ab
• Possible in situ formation of Uranus and Neptune via Pebble Accretion