Paul Cristofari is a Humboldt research fellow at the Georg-August Universität Göttingen. His research leverages high-resolution spectroscopic observations and modelling to study stars in various contexts ; with a particular focus on M dwarfs. Prior to his fellowship, he was a postdoctoral researcher at Leiden Observatory, and a research fellow at the Center for Astrophysics | Harvard & Smithsonian.
Abstract. Magnetic fields play a central role in the formation of stars and planets, drive activity phenomena, and contaminate signals used to detect exoplanets. In this talk, I present a study of the long-term variability of small-scale magnetic fields in M dwarfs — key targets for understanding dynamos in fully convective stars. Using near-infrared high-resolution spectra recorded with SPIRou over multiple years, we derive nightly surface-averaged magnetic field estimates. Strong anti-correlation with temperature variations confirms a direct link to cool features, while long-term field variability hints at complex, possibly cyclic, dynamo processes. I also introduce a fast method for estimating small-scale magnetic field variations from spectra, making it a viable option for its systematic application to large datasets obtained with the upcoming generation of instruments (e.g., WENAOKEAO, Andes at the ELT). Complementing this work, we are extending the measurements to Sun-like stars whose large-scale fields were already characterized, providing a more complete, muti-scale picture of their magnetic properties.
