Evolved stars are the primary engines of galactic chemical enrichment, yet the physical mechanisms governing their intense mass loss remain a major challenge for stellar evolution models. While mass loss is traditionally treated as a spherically symmetric process, the high frequency of binary systems suggests that gravitational interactions with a companion are a dominant force in shaping stellar outflows.

In this talk, I present a high-resolution observational study of the post-Red Supergiant (post-RSG) binary system AFGL 4106. Using the extreme adaptive optics and high-contrast imaging capabilities of VLT/SPHERE, we have successfully resolved the binary components and mapped their immediate circumstellar environment in unprecedented detail.

These observations (Tomassini et al. 2026) reveal a complex interplay between the binary pair and the surrounding material, providing a unique window into how companions steer mass loss during the final stages of stellar evolution. By characterising the morphology of the dusty structures surrounding AFGL 4106, we provide crucial empirical constraints for 3D hydrodynamic models of binary interactions in evolved systems.

Probing the composition of exoplanet atmospheres reveals the physical processes at play and provides insights into their interior and formation history. Atmospheric temperatures are key in shaping these atmospheres and setting molecular abundances. However, warm exoplanets (Teq < 1000 K) are not well understood. JWST opened a new window into these atmospheres thanks to its broad coverage from red to mid-infrared wavelengths and unprecedented sensitivity. Carbon- and sulphur-bearing species are now detected with high significance and their abundances can be measured. In this talk, I will give new insights on the atmospheres of transiting gas giant exoplanets focusing on the warm Neptune WASP-107b, the warm sub-Saturn HAT-P-12b, and the hot Jupiter WASP-43b that has a warm nightside. These studies highlight the importance of processes that alter thermochemical equilibrium and the role of the atmospheric temperature, provide clues on the presence and composition of clouds, but also leaves unanswered questions. I will also present other projects that I conduct with JWST, from the calibration of the MIRI instrument to the search for unknown asteroids.