Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets

Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase the observational signal by increasing reflected light. Here we co...

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Main Authors: Huanzhou Yang, Michelle Hu, Dorian S. Abbot
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Online Access:https://doi.org/10.3847/1538-4357/add46b
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author Huanzhou Yang
Michelle Hu
Dorian S. Abbot
author_facet Huanzhou Yang
Michelle Hu
Dorian S. Abbot
author_sort Huanzhou Yang
collection DOAJ
description Clouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase the observational signal by increasing reflected light. Here we constrain the impact of clouds on the detection of O _2 and O _3 by a direct-imaging telescope such as the Habitable Worlds Observatory (HWO) using observations simulated with the Planetary Spectrum Generator (PSG). We first perform sensitivity tests to show that low clouds enhance O _2 and O _3 detectability while high clouds diminish it, and the effect is greater when cloud particles are smaller. We next apply clouds produced by the cloud microphysics model Community Aerosol and Radiation Model for Atmospheres with varied planetary parameters and clouds drawn from observations of different types of clouds on Earth to PSG. We find that clouds are likely to increase the signal-to-noise ratio of O _2 and O _3 for terrestrial exoplanets under a wide range of scenarios. This work provides important constraints on the impact of clouds on observations by telescopes including HWO.
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spelling doaj-art-e13f591672b944d2b3345c4c848fe6d92025-08-20T02:35:48ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-01986220410.3847/1538-4357/add46bClouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial ExoplanetsHuanzhou Yang0https://orcid.org/0000-0001-8693-7053Michelle Hu1https://orcid.org/0009-0004-1844-0845Dorian S. Abbot2https://orcid.org/0000-0001-8335-6560Department of the Geophysical Sciences, University of Chicago , USADepartment of Physics, University of Chicago , USADepartment of the Geophysical Sciences, University of Chicago , USAClouds are often considered a highly uncertain barrier for detecting biosignatures on exoplanets, especially given intuition gained from transit surveys. However, for direct-imaging reflected light observations, clouds could increase the observational signal by increasing reflected light. Here we constrain the impact of clouds on the detection of O _2 and O _3 by a direct-imaging telescope such as the Habitable Worlds Observatory (HWO) using observations simulated with the Planetary Spectrum Generator (PSG). We first perform sensitivity tests to show that low clouds enhance O _2 and O _3 detectability while high clouds diminish it, and the effect is greater when cloud particles are smaller. We next apply clouds produced by the cloud microphysics model Community Aerosol and Radiation Model for Atmospheres with varied planetary parameters and clouds drawn from observations of different types of clouds on Earth to PSG. We find that clouds are likely to increase the signal-to-noise ratio of O _2 and O _3 for terrestrial exoplanets under a wide range of scenarios. This work provides important constraints on the impact of clouds on observations by telescopes including HWO.https://doi.org/10.3847/1538-4357/add46bAtmospheric cloudsDirect imagingExoplanet atmospheresBiosignatures
spellingShingle Huanzhou Yang
Michelle Hu
Dorian S. Abbot
Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
The Astrophysical Journal
Atmospheric clouds
Direct imaging
Exoplanet atmospheres
Biosignatures
title Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
title_full Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
title_fullStr Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
title_full_unstemmed Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
title_short Clouds Can Enhance Direct-imaging Detection of O2 and O3 on Terrestrial Exoplanets
title_sort clouds can enhance direct imaging detection of o2 and o3 on terrestrial exoplanets
topic Atmospheric clouds
Direct imaging
Exoplanet atmospheres
Biosignatures
url https://doi.org/10.3847/1538-4357/add46b
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AT michellehu cloudscanenhancedirectimagingdetectionofo2ando3onterrestrialexoplanets
AT doriansabbot cloudscanenhancedirectimagingdetectionofo2ando3onterrestrialexoplanets