Charles Cadieux

Charles Cadieux is a postdoctoral researcher at the Trottier Institute for Research on Exoplanets (IREx) since March 2025, after completing a PhD in astrophysics at the same institute under the supervision of René Doyon.

His current research focuses on developing data analysis tools for the James Webb Space Telescope, particularly for the NIRISS instrument, to extract more precise transmission spectra of exoplanets and better probe the chemical composition of their atmospheres. This position also allows him to continue several collaborations initiated in recent years, notably within the NIRPS consortium, which aims to measure the masses of newly discovered exoplanets in the solar neighbourhood.

Charles’s doctoral thesis, completed between 2020 and 2025, focused on the characterization of temperate super-Earths orbiting low-mass stars. The goal was to explore the diversity of internal structures and atmospheric compositions for this largely unexplored class of exoplanets. By combining the transit and radial velocity methods, his work aimed to precisely measure the radii and masses of these planets, enabling the inference of their bulk composition — that is, whether they are predominantly rocky or enriched in volatile materials.

One of the key results of his thesis concerns LHS 1140 b, a super-Earth located in the habitable zone. Observations obtained with James Webb in December 2023 suggest that this planet may host a nitrogen-rich atmosphere. If confirmed, it would mark the first detection of an Earth-like atmosphere on a potentially habitable exoplanet.

More broadly, Charles’s research contributes to growing evidence in recent years pointing to the existence of super-Earths whose relatively low densities suggest a water-rich composition (water worlds). These findings support the idea that around M-type stars, planets form far from their host star in regions where water ice is abundant for accretion, before migrating inward to their present-day orbits.