Now Reading: JWST-TST DREAMS: Secondary Atmosphere Constraints for the Habitable Zone Planet TRAPPIST-1 e
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JWST-TST DREAMS: Secondary Atmosphere Constraints for the Habitable Zone Planet TRAPPIST-1 e
JWST-TST DREAMS: Secondary Atmosphere Constraints for the Habitable Zone Planet TRAPPIST-1 e
Spectral fits to TRAPPIST-1 e’s stellar-contamination-corrected transmission spectrum. Top: bestfitting forward models for three different partial pressures of N2 and CH4 (solid, dotted, and dashed colored lines) compared to a flat line (dotted black line). Bottom: GP+atmosphere retrievals for the centered log-ratio prior (CLR; blue) and log-uniform priors with a ‘ghost’ background gas (gray) compared to a flat line (dotted black line). All models are plotted binned to the same spectral resolution as the data. The wavelengths of potential CH4 absorption bands are annotated. The corresponding corner plot is in Appendix E. The best-fitting forward models and both retrieval approaches independently identify spectral features tentatively attributed to CH4 features in a potentially N2-rich atmosphere. — astro-ph.EP
The TRAPPIST-1 system offers one of the best opportunities to characterize temperate terrestrial planets beyond our own solar system. Within the TRAPPIST-1 system, planet e stands out as highly likely to sustain surface liquid water if it possesses an atmosphere.
Recently, we reported the first JWST/NIRSpec PRISM transmission spectra of TRAPPIST-1 e, revealing significant stellar contamination, which varied between the four visits. Here, we assess the range of planetary atmospheres consistent with our transmission spectrum. We explore a wide range of atmospheric scenarios via a hierarchy of forward modeling and retrievals. We do not obtain strong evidence for or against an atmosphere.
Our results weakly disfavor CO2-rich atmospheres for pressures corresponding to the surface of Venus and Mars and the cloud tops of Venus at 2σ. We exclude H2-rich atmospheres containing CO2 and CH4 in agreement with past work, but find that higher mean molecular weight, N2-rich atmospheres with trace CO2 and CH4 are permitted by the data.
Both a bare rock and N2-rich atmospheric scenario provide adequate fits to the data, but do not fully explain all features, which may be due to either uncorrected stellar contamination or atmospheric signals. Ongoing JWST observations of TRAPPIST-1 e, exploiting consecutive transits with TRAPPIST-1 b, will offer stronger constraints via a more effective stellar contamination correction.
The present work is part of the JWST Telescope Scientist Team (JWST-TST) Guaranteed Time Observations, which is performing a Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (DREAMS).
Ana Glidden, Sukrit Ranjan, Sara Seager, Néstor Espinoza, Ryan J. MacDonald, Natalie H. Allen, Caleb I. Cañas, David Grant, Amélie Gressier, Kevin B. Stevenson, Natasha E. Batalha, Nikole K. Lewis, Douglas Long, Hannah R. Wakeford, Lili Alderson, Ryan C. Challener, Knicole Colón, Jingcheng Huang, Zifan Lin, Dana R. Louie, Elijah Mullens, Kristin S. Sotzen, Jeff A. Valenti, Daniel Valentine, Mark Clampin, C. Matt Mountain, Marshall Perrin, Roeland P. van der Marel
Comments: 29 pages, 8 figures, accepted for publication in ApJL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2509.05407 [astro-ph.EP] (or arXiv:2509.05407v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2509.05407
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Related DOI:
https://doi.org/10.3847/2041-8213/adf62e
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Submission history
From: Ana Glidden
[v1] Fri, 5 Sep 2025 18:00:01 UTC (2,733 KB)
https://arxiv.org/abs/2509.05407
Astrobiology,
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