Kavli Affiliate: Sara Seager
| First 5 Authors: , , , ,
| Summary:
TRAPPIST-1 e is one of the very few rocky exoplanets that is both amenable to
atmospheric characterization and that resides in the habitable zone of its star
— located at a distance from its star such that it might, with the right
atmosphere, sustain liquid water on its surface. Here, we present a set of 4
JWST/NIRSpec PRISM transmission spectra of TRAPPIST-1 e obtained from mid to
late 2023. Our transmission spectra exhibit similar levels of stellar
contamination as observed in prior works for other planets in the TRAPPIST-1
system (Lim et al, 2023; Radica et al., 2024), but over a wider wavelength
range, showcasing the challenge of characterizing the TRAPPIST-1 planets even
at relatively long wavelengths (3-5 um). While we show that current stellar
modeling frameworks are unable to explain the stellar contamination features in
our spectra, we demonstrate that we can marginalize over those features instead
using Gaussian Processes, which enables us to perform novel exoplanet
atmospheric inferences with our transmission spectra. In particular, we are
able to rule out cloudy, primary H$_2$-dominated ($gtrsim$ 80$%$ by volume)
atmospheres at better than a 3$sigma$ level. Constraints on possible secondary
atmospheres on TRAPPIST-1 e are presented in a companion paper (Glidden et al.,
2025). Our work showcases how JWST is breaking ground into the precisions
needed to constrain the atmospheric composition of habitable-zone rocky
exoplanets.
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