Impact of Clouds on the Atmosphere-Mantle Interface of Sub-Neptunes

Abstract

Sub-Neptunes are among the most common type of close-in planets found in our galaxy, yet their bulk composition remains largely uncertain; H-rich envelopes overlaying rocky cores, volatile-rich planets, and carbon-rich interiors all remain viable configurations for members of this population. Atmospheric characterization has been proposed as a means of distinguishing between these scenarios, but growing evidence suggests that sub-Neptunes may host molten atmosphere-mantle interfaces which could alter the composition of their atmosphere. We use the PICASO 1D climate model, coupled to interior-structure and magma-atmosphere chemistry frameworks to quantify how clouds alter the atmospheric and interior structure of sub-Neptunes. For temperate sub-Neptunes like TOI-270 d, we find that clouds can lead to $\ge 1000$ K heating at depth ($\sim 10^4$ bar) and $\sim 600$ K cooling at shallow pressures ($\sim$1 bar). This heating is very sensitive to the cloud sedimentation efficiency and, to a lesser extent, to metallicity. Most sub-Neptunes in our sample should have a molten atmosphere-mantle interface, except TOI-1231 b and GJ 1214 b. For these two planets, cloudy models have a molten interface whereas clear models can allow a solid boundary. Clouds can heat the atmosphere-mantle interfaces by a temperature difference between $\sim 1400-2600$ K for most sub-Neptunes in our sample. Such cloud-driven heating can substantially change the composition of the interface with abundances of O${}_2$, SiH${}_4$, and SiO showing a $\ge 36$\% increase between cloudy and clear models of TOI-270 d. We discuss the implications of our results for the thermal evolution and measurements of intrinsic heat flux for this population.

arXiv commentAccepted for publication in The Astrophysical Journal Letters, Main Text: Pages 1 to 15, 8 Figures, 1 Table, Appendix: Pages 16 to 22, 4 Figures

References in corpus (96)

• The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets
• Planet Occurrence within 0.25 AU of Solar-type Stars from Kepler
• The false positive rate of Kepler and the occurrence of planets
• Planetary Radii across Five Orders of Magnitude in Mass and Stellar Insolation: Application to Transits
• Clouds in the atmosphere of the super-Earth exoplanet GJ 1214b
• Precipitating Condensation Clouds in Substellar Atmospheres
• A super-Earth transiting a nearby low-mass star
• Most 1.6 Earth-Radius Planets are not Rocky
• Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition
• The Evolution of L and T Dwarfs in Color-Magnitude Diagrams
• Growth Model Interpretation of Planet Size Distribution
• C/O ratio as a Dimension for Characterizing Exoplanetary Atmospheres
• Neglected Clouds in T and Y Dwarf Atmospheres
• The Mass-Metallicity Relation for Giant Planets
• Sculpting the Valley in the Radius Distribution of Small Exoplanets as a by-product of Planet Formation: The Core-Powered Mass-Loss Mechanism
• A Framework for Quantifying the Degeneracies of Exoplanet Interior Compositions
• How to Distinguish between Cloudy Mini-Neptunes and Water/Volatile-Dominated Super-Earths
• A Framework for Characterizing the Atmospheres of Low-Mass Low-Density Transiting Planets
• Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b
• HD 209458b in New Light: Evidence of Nitrogen Chemistry, Patchy Clouds and Sub-Solar Water
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars II. Sulfur and Phosphorus
• Photochemically-produced SO${}_2$ in the atmosphere of WASP-39b
• Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low-Mass Dwarf Stars III. Iron, Magnesium, and Silicon
• Three Possible Origins for the Gas Layer on GJ 1214b
• The Atmospheric Signatures of Super-Earths: How to Distinguish Between Hydrogen-Rich and Hydrogen-Poor Atmospheres
• Mass-Metallicity Trends in Transiting Exoplanets from Atmospheric Abundances of H${}_2$O, Na, and K
• Ocean Planet or Thick Atmosphere: On the Mass-Radius Relationship for Solid Exoplanets with Massive Atmospheres
• Quantitatively Assessing the Role of Clouds in the Transmission Spectrum of GJ 1214b
• On the Cool Side: Modeling the Atmospheres of Brown Dwarfs and Giant Planets
• Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation
• Exoplanet Reflected Light Spectroscopy with PICASO
• Predictions of the atmospheric composition of GJ 1132b
• A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
• Volatile-Rich Earth-Mass Planets in the Habitable Zone
• Habitability and Biosignatures of Hycean Worlds
• Condensation-inhibited convection in hydrogen-rich atmospheres: Stability against double-diffusive processes and thermal profiles for Jupiter, Saturn, Uranus, and Neptune
• Treatment of overlapping gaseous absorption with the correlated-k method in hot Jupiter and brown dwarf atmosphere models
• PICASO 3.0: A One-Dimensional Climate Model for Giant Planets and Brown Dwarfs
• Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets
• Haze Production in the Atmospheres of super-Earths and mini-Neptunes: Insights from the Lab
• Atmosphere Origins for Exoplanet Sub-Neptunes
• A super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270
• A High Internal Heat Flux and Large Core in a Warm Neptune Exoplanet
• Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres
• Global-mean Vertical Tracer Mixing in Planetary Atmospheres I: Theory and Fast-rotating Planets
• Superabundance of Exoplanet Sub-Neptunes Explained by Fugacity Crisis
• Microphysics of KCl and ZnS Clouds on GJ 1214b
• A warm Neptune's methane reveals core mass and vigorous atmospheric mixing
• JWST/NIRISS reveals the water-rich "steam world" atmosphere of GJ 9827 d
• The Interior Dynamics of Water Planets
• Ultracool Dwarfs Observed with the Spitzer Infrared Spectrograph. II. Emergence and Sedimentation of Silicate Clouds in L Dwarfs, and Analysis of the Full M5--T9 Field Dwarf Spectroscopic Sample
• The Hazy and Metal-Rich Atmosphere of GJ 1214 b Constrained by Near and Mid-Infrared Transmission Spectroscopy
• Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra
• Aurora: A Generalised Retrieval Framework for Exoplanetary Transmission Spectra
• Probing the Extent of Vertical Mixing in Brown Dwarf Atmospheres with Disequilibrium Chemistry
• How Deep Is the Ocean? Exploring the phase structure of water-rich sub-Neptunes
• Clouds and Clarity: Revisiting Atmospheric Feature Trends in Neptune-size Exoplanets
• Three Small Super-Earths Transiting the nearby star GJ 9827
• Photochemical hazes in sub-Neptunian atmospheres with focus on GJ 1214 b
• Formation and dynamics of water clouds on temperate sub-Neptunes: The example of K2-18b
• The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?
• On the Temperature Profiles and Emission Spectra of Mini-Neptune Atmospheres
• Overcast on Osiris: 3D radiative-hydrodynamical simulations of a cloudy hot Jupiter using the parameterised, phase-equilibrium cloud formation code EddySed
• Hubble Space Telescope transmission spectroscopy for the temperate sub-Neptune TOI-270d: a possible hydrogen-rich atmosphere containing water vapour
• Quartz Clouds in the Dayside Atmosphere of the Quintessential Hot Jupiter HD 189733 b
• Atmospheres as windows into sub-Neptune interiors: coupled chemistry and structure of hydrogen-silane-water envelopes
• Contribution of the core to the thermal evolution of sub-Neptunes
• The importance of silicate vapor in determining the structure, radii, and envelope mass fractions of sub-Neptunes
• A New Sedimentation Model for Greater Cloud Diversity in Giant Exoplanets and Brown Dwarfs
• Transmission spectroscopy for the warm sub-Neptune HD3167c: evidence for molecular absorption and a possible high metallicity atmosphere
• Nitrogen as a Tracer of Giant Planet Formation. I.: A Universal Deep Adiabatic Profile and Semi-analytical Predictions of Disequilibrium Ammonia Abundances in Warm Exoplanetary Atmospheres
• Optical Properties of Organic Haze Analogues in Water-rich Exoplanet Atmospheres Observable with JWST
• Hot Jupiter Diversity and the Onset of TiO/VO Revealed by a Large Grid of Non-Grey Global Circulation Models
• Cleaning our Hazy Lens: Exploring Trends in Transmission Spectra of Warm Exoplanets
• Convective inhibition with an atmosphere, I: super-critical cores on sub-Neptune/super-Earths
• TOI-836: A super-Earth and mini-Neptune transiting a nearby K-dwarf
• TOI-1231 b: A Temperate, Neptune-Sized Planet Transiting the Nearby M3 Dwarf NLTT 24399
• MAGRATHEA: an open-source spherical symmetric planet interior structure code
• The metal-poor atmosphere of a Neptune/Sub-Neptune planet progenitor
• Precise mass determination for the keystone sub-Neptune planet transiting the mid-type M dwarf G 9-40
• The Atmospheres of Rocky Exoplanets II. Influence of surface composition on the diversity of cloud condensates
• Experiments reveal extreme water generation during planet formation
• Coupled Day-Night Models of Exoplanetary Atmospheres
• Magma ocean interactions can explain JWST observations of the sub-Neptune TOI-270 d
• Clouds and Hazes in GJ 1214b's Metal-Rich Atmosphere
• Building Wet Planets through High-Pressure Magma-Hydrogen Reactions
• A young progenitor for the most common planetary systems in the Galaxy
• Soot Planets instead of Water Worlds
• PICASO 4.0: Clouds and Photochemistry in Climate Models of Brown Dwarfs and Exoplanets
• Cloudy mornings and clear evenings on a gas giant exoplanet
• Not All Sub-Neptune Exoplanets Have Magma Oceans
• Searching for Hot Water World Candidates with CHEOPS: Refining the radii and analysing the internal structures and atmospheric lifetimes of TOI-238 b and TOI-1685 b
• Carbon-rich Sub-Neptune Interiors Are Compatible with JWST Observations
• Coupled Thermal-Chemical Evolution Models of Sub-Neptunes Reveal Atmospheric Signatures of Their Formation Location
• The Impact of Irradiation on the Radius and Thermal Evolution of Transiting Brown Dwarfs
• Silane-Methane Competition in Sub-Neptune Atmospheres as a Diagnostic of Metallicity and Magma Oceans