Formation of secondary atmospheres on terrestrial planets by late disk accretion

Abstract

Recently, gas disks have been discovered around main sequence stars well beyond the usual protoplanetary disk lifetimes (i.e., > 10 Myrs), when planets have already formed. These gas disks, mainly composed of CO, carbon, and oxygen seem to be ubiquitous in systems with planetesimal belts (similar to our Kuiper belt), and can last for hundreds of millions of years. Planets orbiting in these gas disks will accrete a large quantity of gas that will transform their primordial atmospheres into new secondary atmospheres with compositions similar to that of the parent gas disk. Here, we quantify how large a secondary atmosphere can be created for a variety of observed gas disks and for a wide range of planet types. We find that gas accretion in this late phase is very significant and an Earth's atmospheric mass of gas is readily accreted on terrestrial planets in very tenuous gas disks. In slightly more massive disks, we show that massive CO atmospheres can be accreted, forming planets with up to sub-Neptune-like pressures. Our new results demonstrate that new secondary atmospheres with high metallicities and high C/O ratios will be created in these late gas disks, resetting their primordial compositions inherited from the protoplanetary disk phase, and providing a new birth to planets that lost their atmosphere to photoevaporation or giant impacts. We therefore propose a new paradigm for the formation of atmospheres on low-mass planets, which can be tested with future observations (JWST, ELT, ARIEL). We also show that this late accretion would show a very clear signature in Sub-Neptunes or cold exo-Jupiters. Finally, we find that accretion creates cavities in late gas disks, which could be used as a new planet detection method, for low mass planets a few au to a few tens of au from their host stars.

arXiv commentPaper accepted and now published in Nature Astronomy. See the published version here: https://www.nature.com/articles/s41550-020-1050-2

References in corpus (69)

• The chemical composition of the Sun
• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Protoplanetary Disks and Their Evolution
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• The Theory of Brown Dwarfs and Extrasolar Giant Planets
• The Mass Dependence Between Protoplanetary Disks and their Stellar Hosts
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• Discovery of a planetary-mass companion within the gap of the transition disk around PDS 70
• Discovery and spectroscopy of the young Jovian planet 51 Eri b with the Gemini Planet Imager
• Two accreting protoplanets around the young star PDS 70
• Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
• Gaseous Mean Opacities for Giant Planet and Ultracool Dwarf Atmospheres over a Range of Metallicities and Temperatures
• The nature of the TRAPPIST-1 exoplanets
• Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b
• Atmospheric Escape and the Evolution of Close-in Exoplanets
• Breeding Super-Earths and Birthing Super-Puffs in Transitional Disks
• Water Vapour Absorption in the Clear Atmosphere of an exo-Neptune
• Water vapour in the atmosphere of the habitable-zone eight Earth-mass planet K2-18 b
• Make Super-Earths, Not Jupiters: Accreting Nebular Gas onto Solid Cores at 0.1 AU and Beyond
• Orbital and atmospheric characterization of the planet within the gap of the PDS 70 transition disk
• Thermal Emission and Albedo Spectra of Super Earths with Flat Transmission Spectra
• Steady-state evolution of debris disks around A stars
• To Cool is to Accrete: Analytic Scalings for Nebular Accretion of Planetary Atmospheres
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• Distribution of Accreting Gas and Angular Momentum onto Circumplanetary Disks
• Age dependence of the Vega Phenomenon: Theory
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• Hydrodynamics of Embedded Planets' First Atmospheres. II. A Rapid Recycling of Atmospheric Gas
• Chemistry of atmospheres formed during accretion of the Earth and other terrestrial planets
• A 40 Myr Old Gaseous Circumstellar Disk at 49 Ceti: Massive CO-Rich Comet Clouds at Young A-Type Stars
• A self-consistent cloud model for brown dwarfs and young giant exoplanets: comparison with photometric and spectroscopic observations
• Collisional processes and size distribution in spatially extended debris discs
• Predictions for the secondary CO, C and O gas content of debris discs from the destruction of volatile-rich planetesimals
• Peering into the formation history of beta Pictoris b with VLTI/GRAVITY long baseline interferometry
• ALMA observations of the molecular gas in the debris disk of the 30 Myr old star HD 21997
• Detection of exocometary CO within the 440 Myr-old Fomalhaut belt: a similar CO+CO${}_2$ ice abundance in exocomets and Solar System comets
• 3D modeling of GJ1214b's atmosphere: formation of inhomogeneous high clouds and observational implications
• The Frequency of Giant impacts on Earth-like Worlds
• Debris Disks in the Scorpius-Centaurus OB Association Resolved by ALMA
• Molecular gas in debris disks around young A-type stars
• The 3D Flow Field Around an Embedded Planet
• A self-consistent model for the evolution of the gas produced in the debris disc of $\beta$ Pictoris
• Three-Dimensional Radiation-Hydrodynamics Calculations of the Envelopes of Young Planets Embedded in Protoplanetary Disks
• Direct Imaging Detection of Methane in the Atmosphere of GJ 504 b
• Common 0.1 bar Tropopause in Thick Atmospheres Set by Pressure-Dependent Infrared Transparency
• An Empirical Planetesimal Belt Radius - Stellar Luminosity Relation
• Suppression of the accretion rate in thin discs around binary black holes
• Late veneer and late accretion to the terrestrial planets
• Radial Surface Density Profiles of Gas and Dust in the Debris Disk around 49 Ceti
• The LEECH Exoplanet Imaging Survey: Characterization of the Coldest Directly Imaged Exoplanet, GJ 504 b, and Evidence for Super-Stellar Metallicity
• LIDT-DD: A new self-consistent debris disc model including radiation pressure and coupling collisional and dynamical evolution
• Interior characterization in multiplanetary systems: TRAPPIST-1
• Imaging [CI] around HD 131835: reinterpreting young debris discs with protoplanetary disc levels of CO gas as shielded secondary discs
• Cometary impactors on the TRAPPIST-1 planets can destroy all planetary atmospheres and rebuild secondary atmospheres on planets f, g, h
• Population synthesis of exocometary gas around A stars
• Herschel HIFI observations of ionised carbon in the β Pictoris debris disk
• New millimeter CO observations of the gas-rich debris disks 49 Cet and HD 32297
• ALMA resolves CI emission from the $\beta$ Pictoris debris disk
• On the Ubiquity and Stellar Luminosity Dependence of Exocometary CO Gas: Detection around M Dwarf TWA 7
• Late Accretion and the Late Veneer
• Envelopes of embedded super-Earths II. Three-dimensional isothermal simulations
• Detection of submillimeter-wave [C I] emission in gaseous debris disks of 49 Ceti and Beta Pictoris
• Hunting for planets in the HL Tau disk
• The magnetorotational instability in debris-disc gas
• Optically Thin Core Accretion: How Planets Get Their Gas in Nearly Gas-Free Disks
• On the unusual gas composition in the Beta Pictoris debris disk
• Atmospheric Mass Loss from High Velocity Giant Impacts

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