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Atmospheric Retrieval of Rocky Exoplanets in Thermal Emission

Presentation #102.334 in the session Poster Session.

Published onJun 20, 2022
Atmospheric Retrieval of Rocky Exoplanets in Thermal Emission

Understanding the presence and nature of rocky exoplanet atmospheres is critical to understanding this diverse population of exoplanets and its potential for habitability. In particular, emission spectroscopy with JWST is a promising technique to determine the presence of and characterise atmospheres of rocky exoplanets, probing both their chemistry and thermal profiles. Comprehensive retrieval approaches are required to interpret such observations within a robust statistical framework. In this talk, we present HyDRo: an atmospheric retrieval framework for thermal emission spectra of rocky exoplanets. HyDRo does not make prior assumptions about the background atmospheric composition, and can therefore be used to interpret spectra of secondary atmospheres with unknown compositions. We further show how HyDRo can be used to assess the chemical constraints which can be placed on rocky exoplanet atmospheres using JWST. We identify the best currently-known rocky exoplanet candidates for spectroscopic observations in thermal emission with JWST, finding >30 known planets whose thermal emission will be detectable by JWST/MIRI in fewer than 10 eclipses at R ~ 10. We then consider the observations required to characterise the atmospheres of three promising rocky exoplanets across the ~400-800K equilibrium temperature range: Trappist-1b, GJ1132b, and LHS3844b. Considering a range of CO2- to H2O-rich atmospheric compositions, we find that CO2 and H2O can be detected in these atmospheres with reasonable amounts of JWST observing time, and that their abundances can be constrained with good precision. HyDRo will allow important atmospheric constraints on rocky exoplanets with JWST observations, providing crucial insights into their geochemical environments.

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