JWST Transmission Spectrum of a GEMS Target: Mitigating Stellar Contamination Effects

Résumé fourni par la source

Giant exoplanets around M dwarfs challenge standard planet-formation theories, and their atmospheres offer key clues to their origins. However, transmission spectra of these planets can be strongly biased by stellar contamination. We present a JWST/NIRSpec PRISM observation of TOI-3235 b, a 0.6 Jupiter-mass planet orbiting a 0.4 solar-mass M dwarf. We compare atmospheric retrievals using a deterministic stellar-contamination model and a model that includes a Gaussian Process to capture residual wavelength-correlated structure. The deterministic model suggests sub-solar metallicity but leaves correlated residuals, while the GP model absorbs this structure and broadens the inferred constraints. These results highlight the need for flexible, physically informed treatments of stellar contamination when interpreting JWST spectra of giant planets around active M dwarfs. Complementary long-baseline stellar monitoring from missions such as Pandora will also help constrain time-variable stellar spectra and improve atmospheric inferences.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.