Exoplanetology: Exoplanets & Exomoons

Do Temperate Rocky Planets Around M Dwarfs have an Atmosphere?

By Keith Cowing

Status Report

astro-ph.EP

March 20, 2024

Filed under astro-ph.EP, atmosphere, exoplanet, habitability, JWST, K2- 18b, LHS1140b, mini-Neptunes, rocky exoplanet, Transmission spectroscopy, TRAPPIST-1, TRAPPIST-1 e, TRAPPIST-1d, TRAPPIST-1f, TRAPPIST-1g

Do Temperate Rocky Planets Around M Dwarfs have an Atmosphere? — Combined transmission spectrum LHS1140b obtained with NIRISS SOSS on December 1st and 26th 2023 overlaid with HST observations (solid grey points; Edwards et al. 2021). The orange 2-envelope is the best TLS model dominated by facula. The dashed line is the predicted GCM model of the mini-Neptune scenario of Cadieux et al. (2024); this model is excluded at more than 5  (Cadieux et al., in prep). — astro-ph.EP

Detecting an atmosphere on nearby temperate planets is one of the most important scientific objectives of the Webb mission, an endeavour in practice limited to a handful of well-characterized planets: Trappist-1d, e, f, g, LHS1140b, and the mini-Neptune K2- 18b.

The first 18 months of atmospheric characterization with JWST have confirmed both its power and versatility to probe exoplanet atmospheres, and have highlighted the challenge of stellar activity in studying those atmospheres through transmission spectroscopy.

Assessing the prevalence of atmosphere in temperate planets with a minimal degree of confidence will require a multi-cycle program of order of a few 1000 hours involving both eclipse photometry and transmission spectroscopy, a program that would have to be executed over a significant fraction of JWST’s lifetime.

The forthcoming 500 hours of Cycle 3 Director Discretionary Time dedicated to exoplanet programs represent a unique opportunity to initiate a deep reconnaissance of habitability of the best keystone temperate planets.

Rene Doyon

Comments: 7 pages, one figure, one table. To appear in the proceedings of the Pontifical Academy of Science workshop on The James Webb Space Telescope: from first light to new worldviews, Vatican City, 27-29 February 2024
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2403.12617 [astro-ph.EP] (or arXiv:2403.12617v1 [astro-ph.EP] for this version)
Submission history
From: Rene Doyon
[v1] Tue, 19 Mar 2024 10:35:20 UTC (343 KB)
https://arxiv.org/abs/2403.12617
Astrobiology

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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