![Transmission spectra of TRAPPIST-1 c from the four JWST/NIRSpec PRISM epochs (4-pixel bins, 0.8–5.0 𝜇m), offset vertically by 200 ppm per epoch for clarity and colour-coded by date, with the inverse-variance-weighted mean spectrum (black, plotted at its true depth). Grey bands mark the stellar H2O features near 1.4 and 1.85 𝜇m. The dotted line marks 2.0 𝜇m, the boundary of the region where the contamination is strongest (Section 3). The 2023 November 8 visit contains a flare during transit and the 2024 July 9 visit shows activity outside transit (Section 2.5). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/Detecting.png?resize=1200%2C716&ssl=1)
[astro-ph.EP] Transmission spectroscopy of rocky exoplanets orbiting late M dwarfs is limited by stellar contamination rather than photon noise.
Stellar Contamination
![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?resize=1200%2C717&ssl=1)
Posted inTRAPPIST-1
Looking For TRAPPIST-1 External Planets’ Emission In JWST Archival Data
[astro-ph.EP] The TRAPPIST-1 system has been thoroughly observed with JWST. Unfortunately, stellar contamination issues strongly limit the interpretation of transit observations.
Posted inExoplanets, -moons, -comets
JWST Transmission Spectroscopy Of TOI-3235 b: Challenges In Constraining Giant Planet Atmospheres Around M Dwarfs Amid Stellar Contamination
[astro-ph.EP] Giant planets orbiting low-mass M dwarfs challenge current planet formation theories, which predict that such planets are unlikely to form. Characterizing their atmospheres can provide key insight into their […]
Posted inAstrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Imaging & Spectroscopy, Interstellar, Status Report
Stellar Contamination Correction Using Back-to-Back Transits of TRAPPIST-1 b and c
Stellar surface heterogeneities, such as spots and faculae, often contaminate exoplanet transit spectra, hindering precise atmospheric characterization.
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
A Population Analysis of 20 Exoplanets Observed from the Optical of the Near-infrared Wavelengths with HST: Evidence for Widespread Stellar Contamination
We present a population study of 20 exoplanets, ranging from Neptune-like to inflated hot-Jupiter planets, observed during transit with the STIS and WFC3 instruments aboard the Hubble Space Telescope.