Chemistry, Climate, and Transmission Spectra of TRAPPIST-1 e Explored with a Multimodel Sparse Sampled Ensemble

Abstract

TRAPPIST-1 e is one of a few habitable zone exoplanets that is amenable to characterization in the near term. In this study our motivations are both scientific and technical. Our technical goal is to establish a multimodel sparse sampled ensemble approach for coherently exploring large unconstrained parameter spaces typical in exoplanet science. Our science goal is to determine relationships that connect observations to the underlying climate across a large parameter space of atmospheric compositions for TRAPPIST-1 e. We consider atmospheric compositions of N2, CO2, CH4, and H2O, with water clouds and photochemical hazes. We use a 1D photochemical model, a 3D climate model, and a transmission spectral model, filtered through a quasi-Monte Carlo sparse sampling approach applied across atmospheric compositions. While clouds and hazes have significant effects on the transmission spectra, CO2 and CH4 can be potentially detected in <10 transits for certain compositional and climate states. Colder climates have better prospects for characterization, due to being relatively dry and having fewer clouds, permitting transmission observations to probe more deeply into their atmospheres. CH4 volume mixing ratios of >$10^{-3}$ trigger strong antigreenhouse cooling, where near-IR absorption simultaneously creates an inversion in the stratosphere and reduces the stellar radiation reaching the planet surface. In such cases, interpreting the disk-averaged emission and albedo at face value can yield misleading conclusions, as here low albedo and high thermal emission are associated with cold planets. Future work will use our sparse sampling approach to explore broader parameter spaces and other observationally amenable exoplanets.

30 pages, 19 figures, 4 tables

References in corpus (62)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• Extreme Water Loss and Abiotic O${}_2$ Buildup On Planets Throughout the Habitable Zones of M Dwarfs
• The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth
• The habitability of Proxima Centauri b II. Possible climates and Observability
• Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST
• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
• Atmospheric Reconnaissance of TRAPPIST-1 b with JWST/NIRISS: Evidence for Strong Stellar Contamination in the Transmission Spectra
• Habitable Evaporated Cores: Transforming Mini-Neptunes into Super-Earths in the Habitable Zones of M Dwarfs
• HAZMAT I: The Evolution of Far-UV and Near-UV Emission from Early M Stars
• Day-night cloud asymmetry prevents early oceans on Venus but not on Earth
• Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets
• Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System
• Treatment of overlapping gaseous absorption with the correlated-k method in hot Jupiter and brown dwarf atmosphere models
• Detectability of atmospheric features of Earth-like planets in the habitable zone around M dwarfs
• Persistence of Flare-Driven Atmospheric Chemistry on Rocky Habitable Zone Worlds
• Reconnaissance of the TRAPPIST-1 exoplanet system in the Lyman-$\alpha$ line
• Early 2017 observations of TRAPPIST-1 with $\text{Spitzer}$
• Predicting the Extreme Ultraviolet Radiation Environment of Exoplanets Around Low-Mass Stars: the TRAPPIST-1 System
• The Case and Context for Atmospheric Methane as an Exoplanet Biosignature
• A review of possible planetary atmospheres in the TRAPPIST-1 system
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope IV. Capabilities and predicted performance for exoplanet characterization
• The atmospheric circulation and climate of terrestrial planets orbiting Sun-like and M-dwarf stars over a broad range of planetary parameters
• Photochemistry of Anoxic Abiotic Habitable Planet Atmospheres: Impact of New H${}_2$O Cross-Sections
• The Hazy and Metal-Rich Atmosphere of GJ 1214 b Constrained by Near and Mid-Infrared Transmission Spectroscopy
• TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Motivations and protocol version 1.0
• The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Part II: Moist Cases -- The Two Waterworlds
• The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Part I: Dry Cases -- The fellowship of the GCMs
• Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets
• Atmospheric convection plays a key role in the climate of tidally-locked terrestrial exoplanets: insights from high-resolution simulations
• The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Part III: Simulated Observables -- The return of the spectrum
• Spectrum-driven Planetary Deglaciation Due to Increases in Stellar Luminosity
• HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star
• LHS 1140 b is a potentially habitable water world
• Predictions for Observable Atmospheres of Trappist-1 Planets from a Fully Coupled Atmosphere-Interior Evolution Model
• Laboratory Investigations of Titan Haze Formation: In Situ Measurement of Gas and Particle Composition
• Effects of UV stellar spectral uncertainty on the chemistry of terrestrial atmospheres
• Water Condensation Zones around Main Sequence Stars
• Hot Jupiter Diversity and the Onset of TiO/VO Revealed by a Large Grid of Non-Grey Global Circulation Models
• The Effect of Substellar Continent Size on Ocean Dynamics of Proxima Centauri b
• Optical Properties of Organic Haze Analogues in Water-rich Exoplanet Atmospheres Observable with JWST
• Water Ice Cloud Variability & Multi-Epoch Transmission Spectra of TRAPPIST-1e
• HAZMAT II: Ultraviolet Variability of Low-Mass Stars in the GALEX Archive
• Implications of atmospheric nondetections for Trappist-1 inner planets on atmospheric retention prospects for outer planets
• Detecting the proposed CH4-CO2 biosignature pair with the James Webb Space Telescope: TRAPPIST-1e and the effect of cloud/haze
• Terminator Habitability: the Case for Limited Water Availability on M-dwarf Planets
• Aerosols are not Spherical Cows: Using Discrete Dipole Approximation to Model the Properties of Fractal Particles
• The Effect of Land Albedo on the Climate of Land-Dominated Planets in the TRAPPIST-1 System
• Sporadic Spin-Orbit Variations in Compact Multi-planet Systems and their Influence on Exoplanet Climate
• How does Background Air Pressure Influence the Inner Edge of the Habitable Zone for Tidally Locked Planets in a 3D View?
• Stratospheric dayside-to-nightside circulation drives the 3-D ozone distribution on synchronously rotating rocky exoplanets
• GCM Constraints on the Detectability of the CO${}_2$-CH${}_4$ Biosignature Pair on TRAPPIST-1e with JWST
• The Sparse Atmospheric MOdel Sampling Analysis (SAMOSA) intercomparison: Motivations and protocol version 1.0. A CUISINES model intercomparison project
• Relative abundances of CO2, CO, and CH4 in atmospheres of Earth-like lifeless planets
• Greater climate sensitivity and variability on TRAPPIST-1e than Earth
• Smaller Sensitivity of Precipitation to Surface Temperature under Massive Atmospheres
• 3D simulations of TRAPPIST-1e with varying CO2, CH4 and haze profiles
• Atmospheric Overturning Circulation on Dry, Tidally-locked Rocky Planets is Mainly Driven by Radiative Cooling
• Controls of Atmospheric Methane on Early Earth and Inhabited Earth-like Terrestrial Exoplanets
• Interpolation and synthesis of sparse samples in exoplanet atmospheric modeling
• From Global Climate Models (GCMs) to Exoplanet Spectra with the Global Emission Spectra (GlobES)