Hydrodynamics of Embedded Planets' First Atmospheres. II. A Rapid Recycling of Atmospheric Gas

Abstract

Following Paper I we investigate the properties of atmospheres that form around small protoplanets embedded in a protoplanetary disc by conducting hydrodynamical simulations. These are now extended to three dimensions, employing a spherical grid centred on the planet. Compression of gas is shown to reduce rotational motions. Contrasting the 2D case, no clear boundary demarcates bound atmospheric gas from disc material; instead, we find an open system where gas enters the Bondi sphere at high latitudes and leaves through the midplane regions, or, vice versa, when the disc gas rotates sub-Keplerian. The simulations do not converge to a time-independent solution; instead, the atmosphere is characterized by a time-varying velocity field. Of particular interest is the timescale to replenish the atmosphere by nebular gas, $t_{\mathrm{replenish}}$. It is shown that the replenishment rate, $M_{\mathrm{atm}}/t_{\mathrm{replenish}}$, can be understood in terms of a modified Bondi accretion rate, $\sim$$R_{\mathrm{Bondi}}^2{\rho }_{\mathrm{gas}}{v}_{\mathrm{Bondi}}$, where $v_{\mathrm{Bondi}}$ is set by the Keplerian shear or the magnitude of the sub-Keplerian motion of the gas, whichever is larger. In the inner disk, the atmosphere of embedded protoplanets replenishes on a timescale that is shorter than the Kelvin-Helmholtz contraction (or cooling) timescale. As a result, atmospheric gas can no longer contract and the growth of these atmospheres terminates. Future work must confirm whether these findings continue to apply when the (thermodynamical) idealizations employed in this study are relaxed. But if shown to be broadly applicable, replenishment of atmospheric gas provides a natural explanation for the preponderance of gas-rich but rock-dominant planets like super-Earths and mini-Neptunes.

arXiv comment15 pages, 13 figures, submitted to MNRAS. Comments welcome

References in corpus (33)

• PLUTO: a Numerical Code for Computational Astrophysics
• The false positive rate of Kepler and the occurrence of planets
• Kepler planets: a tale of evaporation
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• The Mass-Radius Relation for 65 Exoplanets Smaller than 4 Earth Radii
• The Minimum-Mass Extrasolar Nebula: In-Situ Formation of Close-In Super-Earths
• Atmospheres of protoplanetary cores: critical mass for nucleated instability
• Models of Jupiter's Growth Incorporating Thermal and Hydrodynamic Constraints
• Orbital Migration and Mass Accretion of Protoplanets in 3D Global Computations with Nested Grids
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• A Plateau in the Planet Population Below Twice the Size of Earth
• Density and Eccentricity of Kepler Planets
• Distribution of Accreting Gas and Angular Momentum onto Circumplanetary Disks
• In-situ Accretion of Hydrogen-Rich Atmospheres on Short-Period Super-Earths: Implications for the Kepler-11 Planets
• Accretion of Jupiter-mass Planets in the Limit of Vanishing Viscosity
• On the Minimum Core Mass for Giant Planet Formation at Wide Separations
• Nested-grid calculations of disk-planet interaction
• Circumplanetary disc properties obtained from radiation hydrodynamical simulations of gas accretion by protoplanets
• Particle Concentration At Planet Induced Gap Edges and Vortices: I. Inviscid 3-D Hydro Disks
• An Atmospheric Structure Equation for Grain Growth
• Gas accretion onto planetary cores: three-dimensional self-gravitating radiation hydrodynamical calculations
• Global hydromagnetic simulations of a planet embedded in a dead zone: gap opening, gas accretion and formation of a protoplanetary jet
• Grain opacity and the bulk composition of extrasolar planets. II. An analytical model for the grain opacity in protoplanetary atmospheres
• Three-Dimensional Radiation-Hydrodynamics Calculations of the Envelopes of Young Planets Embedded in Protoplanetary Disks
• Growing and moving low-mass planets in non-isothermal disks
• Three Dimensional MHD Simulations of Accretion to an Inclined Rotator: The "Cubed Sphere" Method
• Hydrodynamics of Embedded Planets' First Atmospheres. I. A Centrifugal Growth Barrier for 2D Flows
• Accretion and Evolution of ~2.5 Earth-mass Planets with Voluminous H/He Envelopes
• Critical Core Masses for Gas Giant Formation with Grain-Free Envelopes
• Application of the Cubed-Sphere Grid to Tilted Black-Hole Accretion Disks
• The steady-state flow pattern past gravitating bodies
• RODEO: a new method for planet-disk interaction
• Formation of Isothermal Disks around Protoplanets. I. Introductory Three-Dimensional Global Simulations for Sub-Neptune-Mass Protoplanets

Cited by in corpus (141)

• Super-Earth Atmospheres: Self-Consistent Gas Accretion and Retention
• 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
• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• To Cool is to Accrete: Analytic Scalings for Nebular Accretion of Planetary Atmospheres
• Atmospheres of low-mass planets: the "boil-off"
• The Nature of the Radius Valley: Hints from Formation and Evolution Models
• The New Generation Planetary Population Synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems
• How drifting and evaporating pebbles shape giant planets I: Heavy element content and atmospheric C/O
• Reduced gas accretion on super-Earths and ice giants
• Atmosphere Origins for Exoplanet Sub-Neptunes
• Hydrodynamics of embedded planets' first atmospheres - III. The role of radiation transport for super-Earth planets
• The formation of Jupiter by hybrid pebble-planetesimal accretion
• Coorbital thermal torques on low-mass protoplanets
• Gap Opening in 3D: Single Planet Gaps
• Eccentric Jupiters via Disk-Planet Interactions
• The 3D Flow Field Around an Embedded Planet
• Catching drifting pebbles I. Enhanced pebble accretion efficiencies for eccentric planets
• How cores grow by pebble accretion I. Direct core growth
• Forming spectroscopic massive proto-binaries by disk fragmentation
• Planetary population synthesis
• Suppression of atmospheric recycling of planets embedded in a protoplanetary disc by buoyancy barrier
• The Boundary between Gas-rich and Gas-poor Planets
• Convergence of the critical cooling rate for protoplanetary disk fragmentation achieved; the key role of numerical dissipation of angular momentum
• Pebbles versus Planetesimals: The case of Trappist-1
• Circumplanetary Disk Dynamics in the Isothermal and Adiabatic Limits
• Effects of the Planetary Temperature on the Circumplanetary Disk and on the Gap
• Hydrogen dominated atmospheres on terrestrial mass planets: evidence, origin and evolution
• The formation of mini-Neptunes
• How planets grow by pebble accretion. III. Emergence of an interior composition gradient
• A Tale of Planet Formation: From Dust to Planets
• Quasi-static contraction during runaway gas accretion onto giant planets
• The last migration trap of compact objects in AGN accretion disc
• Dawes Review. The tidal downsizing hypothesis of planet formation
• The Planetary Accretion Shock: I. Framework for Radiation-hydrodynamical Simulations and First Results
• A fading radius valley towards M-dwarfs, a persistent density valley across stellar types
• Tidal Inflation Reconciles Low-Density Sub-Saturns with Core Accretion
• How planets grow by pebble accretion II: Analytical calculations on the evolution of polluted envelopes
• Clouds of Fluffy Aggregates: How They Form in Exoplanetary Atmospheres and Influence Transmission Spectra
• Is the ring inside or outside the planet?: The effect of planet migration on dust rings
• Discovery of an au-scale excess in millimeter emission from the protoplanetary disk around TW Hya
• One year of AU Mic with HARPS: I -- measuring the masses of the two transiting planets
• Pebble dynamics and accretion onto rocky planets. I. Adiabatic and convective models
• Meridional Circulation of Dust and Gas in the Circumstellar Disk: Delivery of Solids onto the Circumplanetary Region
• The maximum mass of planetary embryos formed in core-accretion models
• Constraining the entropy of formation from young transiting planets
• N-body simulations of planet formation via pebble accretion I: First Results
• Horseshoe drag in three-dimensional globally isothermal disks
• Detectability of embedded protoplanets from hydrodynamical simulations
• The Imprint of the Protoplanetary Disk in the Accretion of Super-Earth Envelopes
• Giant planet formation models with a self-consistent treatment of the heavy elements
• Planet Formation: An Optimized Population-Synthesis Approach
• Envelopes of embedded super-Earths II. Three-dimensional isothermal simulations
• Steady State by Recycling prevents Premature Collapse of Protoplanetary Atmospheres
• Super-Earths and Earth-like Exoplanets
• Metallicity effect and planet mass function in pebble-based planet formation models
• In Situ Formation of Icy Moons of Uranus and Neptune
• Setting the Stage: Planet formation and Volatile Delivery
• Gas flow around a planet embedded in a protoplanetary disc: the dependence on the planetary mass
• Formation of planetary systems by pebble accretion and migration: Hot super-Earth systems from breaking compact resonant chains
• Do the TRAPPIST-1 Planets Have Hydrogen-rich Atmospheres?
• A sub-Neptune and a non-transiting Neptune-mass companion unveiled by ESPRESSO around the bright late-F dwarf HD 5278 (TOI-130)
• The Preservation of Super Earths and the Emergence of Gas Giants after Their Progenitor Cores have Entered the Pebble Isolation Phase
• The maximum accretion rate of a protoplanet: how fast can runaway be?
• Pebble Accretion in Turbulent Protoplanetary Disks
• Formation of secondary atmospheres on terrestrial planets by late disk accretion
• N-body simulations of planet formation via pebble accretion II. How various giant planets form
• Accretion of Gas Giants Constrained by the Tidal Barrier
• Makemake + Sedna: A Continuum Radiation Transport and Photoionization Framework for Astrophysical Newtonian Fluid Dynamics
• Radial Gradients in Dust-to-Gas Ratio Lead to Preferred Region for Giant Planet Formation
• Recycling of the first atmospheres of embedded planets: Dependence on core mass and optical depth
• Global 3D Radiation Hydrodynamic Simulations of Proto-Jupiter's Convective Envelope
• ALMA observations require slower Core Accretion runaway growth
• Hydrodynamical simulations of protoplanetary disks including irradiation of stellar photons. I. Resolution study for Vertical Shear Instability (VSI)
• Atmospheric Recyling of Volatiles by Pebble-Accreting Planets
• Unified simulations of planetary formation and atmospheric evolution: Effects of pebble accretion, giant impacts, and stellar irradiations on super-Earth formation
• How planets grow by pebble accretion IV: Envelope opacity trends from sedimenting dust and pebbles
• Deep and wide gaps by super Earths in low-viscosity discs
• Inner rocky super-Earth formation: distinguishing the formation pathways in viscously heated and passive discs
• Spinning up planetary bodies by pebble accretion
• The metal-poor atmosphere of a Neptune/Sub-Neptune planet progenitor
• Oscillatory migration of accreting protoplanets driven by a 3D distortion of the gas flow
• Influences of three-dimensional gas flow induced by protoplanets on pebble accretion --$\mathrm{I}$. shear regime
• The 3D dust and opacity distribution of protoplanets in multi-fluid global simulations
• Revising the Giant Planet Mass-Metallicity Relation: Deciphering the Formation Sequence of Giant Planets
• Pebble dynamics and accretion onto rocky planets. II. Radiative models
• The diverse lives of massive protoplanets in self-gravitating discs
• Close-in Super-Earths: The first and the last stages of planet formation in an MRI-accreting disc
• Physics of Planet Trapping with Applications to HL Tau
• Unified simulations of planetary formation and atmospheric evolution II: Rapid disk clearing by photoevaporation yields low-mass super-Earth atmospheres
• Prograde and Retrograde Gas Flow around Disk-embedded Companions: Dependence on Eccentricity, Mass and Disk Properties
• Tidal Heating of Young Super-Earth Atmospheres
• TW Hya: an old protoplanetary disc revived by its planet
• Planetary Torque in 3D Isentropic Disks
• Mapping the Outcomes of Stellar Evolution in the Disks of Active Galactic Nuclei
• The Growth of Protoplanets via the Accretion of Small Bodies in Disks Perturbed by the Planetary Gravity
• Pebble-driven migration of low-mass planets in the 2D regime of pebble accretion
• Episodic accretion and mergers during growth of massive protostars
• Envelopes of embedded super-Earths I. Two-dimensional simulations
• Restrictions on the Growth of Gas Giant Cores via Pebble Accretion
• Solving for the 2D Water Snowline with Hydrodynamic Simulations. Emergence of gas outflow, water cycle and temperature plateau
• Limits on Protoplanet Growth by Accretion of Small Solids
• Sublimation of refractory minerals in the gas envelopes of accreting rocky planets
• Exoplanet atmosphere evolution: emulation with neural networks
• Gas-Assisted Growth of Protoplanets in a Turbulent Medium
• On the suppression of giant planet formation around low-mass stars in clustered environments
• Mars' atmospheric neon suggests volatile-rich primitive mantle
• Spin of protoplanets generated by pebble accretion: Influences of protoplanet-induced gas flow
• Three-Dimensional Dust Stirring by a Giant Planet Embedded in a Protoplanetary Disk
• How planets form by pebble accretion V. Silicate rainout delays contraction of sub-Neptunes
• ALMA constraints on assembly of Core Accretion planets
• A brief overview of planet formation
• The K2-ESPRINT Project VI: K2-105 b, a Hot-Neptune around a Metal-rich G-dwarf
• Influences of protoplanet-induced three-dimensional gas flow on pebble accretion $\mathrm{I}\mathrm{I}$. Headwind regime
• The Dynamic Proto-atmospheres around Low-Mass Planets with Eccentric Orbits
• Delivery of gas onto the circumplanetary disk of giant planets: Planetary-mass dependence of the source region of accreting gas and mass accretion rate
• A limit on gas accretion onto close-in super-Earth cores from disk accretion
• Unveiling the Planet Population at Birth
• Self-gravitating planetary envelopes and the core-nucleated instability
• Meridional Circulation driven by Planetary Spiral Wakes in Radiative and Magnetized Protoplanetary Discs
• Dust ring and gap formation by gas flow induced by low-mass planets embedded in protoplanetary disks $\mathrm{I}$. Steady-state model
• How Flow Isolation May Set the Mass Scale for Super-Earth Planets
• A formation pathway for terrestrial planets with moderate water content involving atmospheric-volatile recycling
• On the origin of transition disk cavities: Pebble-accreting protoplanets vs Super-Jupiters
• Giant planet formation via pebble accretion across different stellar masses
• Dust ring and gap formation by gas flow induced by low-mass planets embedded in protoplanetary disks $\mathrm{II}$. Time-dependent model
• Formation of Super-Earths
• The influence of a static planetary atmosphere on spin transfer during pebble accretion
• Possible formation pathways for the low density Neptune-mass planet HAT-P-26b
• On the Efficacy of Ocean Formation with a Primordial Hydrogen Atmosphere
• Diversity of Exoplanets
• Interpreting the atmospheric composition of exoplanets: sensitivity to planet formation assumptions
• Evolution and Observable Properties of Rocky Planet Atmospheres
• The role of atmospheric outflows in the migration of hot Jupiters
• Compositional Turbulence and Layering in the Gaseous Envelopes of Forming Planets
• Late gas released in the young Kuiper belt could have significantly contributed to the carbon enrichment of the atmospheres of Neptune and Uranus
• Interior dynamics of envelopes around disk-embedded planets
• Ohmic dissipation during the formation of super-Earth
• Possible in situ formation of Uranus and Neptune via Pebble Accretion
• The effect of late giant collisions on the atmospheres of protoplanets and the formation of cold sub-Saturns
• Retention of primordial atmospheres through giant impacts