Interior-atmosphere modelling to assess the observability of rocky planets with JWST

Abstract

There is a degeneracy in the interior structure between a planet that has no atmosphere and a small Fe content, and a planet that has a thin atmosphere and a higher core mass fraction. We present a self-consistent interior-atmosphere model to constrain the volatile mass fraction, surface pressure, and temperature of rocky planets with water and CO${}_2$ atmospheres. The parameters obtained in our analysis can be used to predict observations in emission spectroscopy and photometry with JWST, which can determine the presence of an atmosphere and, if present, its composition. We coupled a 1D interior model with a supercritical water layer to an atmospheric model. In order to obtain the bolometric emission and Bond albedo for an atmosphere in radiative-convective equilibrium, we used a low-resolution k-correlated model within our retrieval of planetary mass, radius, and host stellar abundances. We generated emission spectra with the same model at a higher resolution (R = 200-300). An adaptive Markov chain Monte Carlo was employed for an efficient sampling of the parameter space at low volatile mass fractions. From our interior structure retrieval, TRAPPIST-1 c is most likely to present a bare surface, although the presence of an atmosphere cannot be ruled out. We estimate a 1$\sigma$ confidence interval of the surface pressure for a water-dominated atmosphere of $P_{surf}=40\pm 40$ bar. We generated spectra for these two scenarios to compare with the emission flux of TRAPPIST-1 c recently observed in the MIRI F1500W filter. This is compatible with bare rock surfaces or a thin atmosphere with little or no CO${}_2$. In the case of 55 Cancri e, a combined spectrum with NIRCam and MIRI LRS may present high uncertainties at wavelengths between 3 and 3.7 $\mu$m. However, this does not affect the identification of H${}_2$O because it does not present spectral features in this wavelength range.

14 pages, 6 figures. Accepted for publication in A&A

References in corpus (31)

• The James Webb Space Telescope
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• Atmospheric Sulfur Photochemistry on Hot Jupiters
• Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST
• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
• A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
• Abundances in the Local Region II: F, G and K Dwarfs and Subgiants
• Self-luminous and irradiated exoplanetary atmospheres explored with HELIOS
• The interior and atmosphere of the habitable-zone exoplanet K2-18b
• Mass-radius relationships for irradiated ocean planets
• Linking the Climate and Thermal Phase Curve of 55 Cancri e
• Constraints on Super-Earths Interiors from Stellar Abundances
• A Case for an Atmosphere on Super-Earth 55 Cancri e
• K2 and Spitzer phase curves of the rocky ultra-short-period planet K2-141 b hint at a tenuous rock vapor atmosphere
• Characterisation of the hydrospheres of TRAPPIST-1 planets
• Constraining the Thickness of the Atmosphere of TRAPPIST-1 b from its JWST Secondary Eclipse Observation
• Predicted diversity in water content of terrestrial exoplanets orbiting M dwarfs
• No escaping helium from 55 Cnc e
• A Heavy Molecular Weight Atmosphere for the Super-Earth π Men c
• Jupiter's formation in the vicinity of the amorphous ice snowline
• The importance of silicate vapor in determining the structure, radii, and envelope mass fractions of sub-Neptunes
• Spectral binning of precomputed correlated-k coefficients
• Possible Internal Structures and Compositions of Proxima Centauri b
• Optical Transmission Spectroscopy of the Terrestrial Exoplanet LHS 3844b from 13 Ground-Based Transit Observations
• The PEPSI Exoplanet Transit Survey (PETS) I: Investigating the presence of a silicate atmosphere on the super-Earth 55 Cnc e
• Waterworlds Probably Do Not Experience Magmatic Outgassing
• Water content trends in K2-138 and other low-mass multiplanetary systems
• TOI-220 $b$: a warm sub-Neptune discovered by TESS
• An Equation of State of CO for use in Planetary Modeling

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