Clouds can enhance direct imaging detection of O2 and O3 on terrestrial exoplanets

Fuente: arXiv
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Main Authors: Yang, Huanzhou, Hu, Michelle, Abbot, Dorian S.
Format: Preprint
Published: 2025
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author Yang, Huanzhou
Hu, Michelle
Abbot, Dorian S.
author_facet Yang, Huanzhou
Hu, Michelle
Abbot, Dorian S.
contents 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 O2 and O3 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 O2 and O3 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 CARMA 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 SNR of O2 and O3 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.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07760
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Clouds can enhance direct imaging detection of O2 and O3 on terrestrial exoplanets
Yang, Huanzhou
Hu, Michelle
Abbot, Dorian S.
Earth and Planetary Astrophysics
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 O2 and O3 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 O2 and O3 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 CARMA 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 SNR of O2 and O3 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.
title Clouds can enhance direct imaging detection of O2 and O3 on terrestrial exoplanets
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2505.07760