HyDRo: Atmospheric retrieval of rocky exoplanets in thermal emission
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Publication Date
2022-02-15Journal Title
Monthly Notices of the Royal Astronomical Society
ISSN
0035-8711
Publisher
Oxford University Press (OUP)
Type
Article
This Version
AM
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Piette, A., Nikku, M., & Mandell, A. (2022). HyDRo: Atmospheric retrieval of rocky exoplanets in thermal emission. Monthly Notices of the Royal Astronomical Society https://doi.org/10.1093/mnras/stab3612
Abstract
Emission spectroscopy is a promising technique to observe atmospheres of
rocky exoplanets, probing both their chemistry and thermal profiles. 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 use HyDRo to assess the
chemical constraints which can be placed on rocky exoplanet atmospheres using
JWST. Firstly, we identify the best currently-known rocky exoplanet candidates
for spectroscopic observations in thermal emission with JWST, finding >30 known
rocky exoplanets 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
~400-800 K equilibrium temperature range: Trappist-1 b, GJ 1132 b, and LHS 3844
b. Considering a range of CO_2- to H_2O-rich atmospheric compositions, we find
that as few as 8 eclipses of LHS 3844 b or GJ 1132 b with MIRI will be able to
place important constraints on the chemical compositions of their atmospheres.
This includes confident detections of CO_2 and H_2O in the case of a cloud-free
CO_2-rich composition, besides ruling out a bare rock scenario. Similarly, 30
eclipses of Trappist-1 b with MIRI/LRS can allow detections of a cloud-free
CO_2-rich or CO_2-H_2O atmosphere. HyDRo will allow important atmospheric
constraints for rocky exoplanets using JWST observations, providing clues about
their geochemical environments.
Keywords
astro-ph.EP, astro-ph.EP
Identifiers
External DOI: https://doi.org/10.1093/mnras/stab3612
This record's URL: https://www.repository.cam.ac.uk/handle/1810/332605
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