![Simulations of the external planets’ (d to h) contributions at the times of JWST observations (represented in color over the bare rocks total curve). Relative fluxes were simulated using the SPHINX spectrum at 12.8 microns. The contributions of each planet are shown in colored dotted lines and the case of all planets with thick atmospheres in dashed grey. The total phase curves correspond to the total contribution of the external planets. Eclipses are displayed but not transits. Visit 1 of GTO 1279 is not displayed as the observational strategy from this visit was different from the others and less precise (Ducrot et al. 2024) -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Looking.png?fit=1200%2C672&ssl=1)
[astro-ph.EP] The TRAPPIST-1 system has been thoroughly observed with JWST. Unfortunately, stellar contamination issues strongly limit the interpretation of transit observations.
As for emission observations, only the two closest planets have been observed through five dedicated JWST programs. We gathered all these emission observations and tried to detect the combined emission of the external planets in previous JWST MIRI observations of TRAPPIST-1; this paper presents our approach and our results.
We could not achieve sufficient precision to detect the thermal emission of the outer planets and to discriminate between an all-bare rocks and an all-atmospheres scenario.
However, we show that a~60 hours continuous observations at a specific phase range, when the gradient of thermal flux from the outer planets is maximum, could allow us to achieve this goal.
Louis-Julien Cartigny, Alice Maurel, Elsa Ducrot, Taylor J. Bell
Comments: 9 pages, 6 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.18626 [astro-ph.EP] (or arXiv:2608.18626v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.18626
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Submission history
From: Louis-Julien Cartigny
[v1] Wed, 19 Aug 2026 07:21:58 UTC (4,666 KB)
https://arxiv.org/abs/2608.18626
Astrobiology, exoplanet,
