HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission

Anjali A A Piette; Nikku Madhusudhan; Avi M Mandell

doi:10.1093/mnras/stab3612

HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission

Anjali A A Piette^*, Nikku Madhusudhan^*, Avi M Mandell

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

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. First, 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 characterize 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 CO₂- to H₂O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO₂ and H₂O in the case of a cloud-free CO₂-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 CO₂-rich or CO₂-H₂O atmosphere. HYDRo will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.

Original language	English
Pages (from-to)	2565–2584
Number of pages	20
Journal	Monthly Notices of the Royal Astronomical Society
Volume	511
Issue number	2
Early online date	11 Dec 2021
DOIs	https://doi.org/10.1093/mnras/stab3612
Publication status	Published - Apr 2022

Bibliographical note

Acknowledgments:
We thank the anonymous reviewer for their thorough and helpful comments on our manuscript. We also thank Subhajit Sarkar for help with validating our PandExo uncertainties against JexoSim. AAAP acknowledges support from the UK Science and Technology Facilities Council (STFC) towards her doctoral studies. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.

Keywords

planets and satellites: atmospheres
planets and satellites: composition
infrared: planetary systems

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Cite this

@article{6734b3924ad44b38a293da64b57851c2,

title = "HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission",

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. First, 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 characterize 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 CO2- to H2O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO2 and H2O in the case of a cloud-free CO2-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 CO2-rich or CO2-H2O atmosphere. HYDRo will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.",

keywords = "planets and satellites: atmospheres, planets and satellites: composition, infrared: planetary systems",

author = "Piette, {Anjali A A} and Nikku Madhusudhan and Mandell, {Avi M}",

note = "Acknowledgments: We thank the anonymous reviewer for their thorough and helpful comments on our manuscript. We also thank Subhajit Sarkar for help with validating our PandExo uncertainties against JexoSim. AAAP acknowledges support from the UK Science and Technology Facilities Council (STFC) towards her doctoral studies. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.",

year = "2022",

month = apr,

doi = "10.1093/mnras/stab3612",

language = "English",

volume = "511",

pages = "2565–2584",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "SIPRI/Oxford University Press",

number = "2",

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TY - JOUR

T1 - HyDRo

T2 - atmospheric retrieval of rocky exoplanets in thermal emission

AU - Piette, Anjali A A

AU - Madhusudhan, Nikku

AU - Mandell, Avi M

N1 - Acknowledgments: We thank the anonymous reviewer for their thorough and helpful comments on our manuscript. We also thank Subhajit Sarkar for help with validating our PandExo uncertainties against JexoSim. AAAP acknowledges support from the UK Science and Technology Facilities Council (STFC) towards her doctoral studies. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program.

PY - 2022/4

Y1 - 2022/4

N2 - 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. First, 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 characterize 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 CO2- to H2O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO2 and H2O in the case of a cloud-free CO2-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 CO2-rich or CO2-H2O atmosphere. HYDRo will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.

AB - 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. First, 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 characterize 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 CO2- to H2O-rich atmospheric compositions, we find that as few as eight eclipses of LHS 3844 b or GJ 1132 b with MIRI LRS will be able to place important constraints on the chemical compositions of their atmospheres. This includes confident detections of CO2 and H2O in the case of a cloud-free CO2-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 CO2-rich or CO2-H2O atmosphere. HYDRo will allow important atmospheric constraints for rocky exoplanets using JWST observations, providing clues about their geochemical environments.

KW - planets and satellites: atmospheres

KW - planets and satellites: composition

KW - infrared: planetary systems

U2 - 10.1093/mnras/stab3612

DO - 10.1093/mnras/stab3612

M3 - Article

SN - 0035-8711

VL - 511

SP - 2565

EP - 2584

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 2

ER -

HyDRo: atmospheric retrieval of rocky exoplanets in thermal emission

Abstract

Bibliographical note

Keywords

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