Research

My research focuses mainly on the detection and characterisation of exoplanets around nearby active low-mass stars, from Solar analogs to ultracool dwarfs, and from the protostellar phase to the end of the main sequence. My activities are structured along three main directions:

• I. Improving the filtering of the spectroscopic signals induced by the magnetic activity of low-mass stars: I dedicated a substantial fraction of my PhD to study the velocimetric detection of exoplanets around nearby red dwarfs and pre-main sequence stars with the near-infrared spectropolarimeter SPIRou, first through simulations, prior to the first SPIRou observations (in 2019), then with actual observations of the young rebel AU Mic. I still devote a significant part of my postdoctoral contract at the University of Oxford to explore and implement new methods to correct activity-induced variations in high-resolution spectra of solar-like stars.

• II. Modelling stellar magnetic fields and activity signals to better understand their generation, evolution and interactions with close-in planets: Understanding the physical processes underlying stellar magnetic fields and associated activity phenomena is primordial to come up with more accurate models of their spectral contributions. During my PhD, I analysed polarized spectra of various young and evolved low-mass stars including the planet-hosting stars AU Mic and Proxima Centauri. This allowed us to obtain an estimate of the surface distribution of magnetic field for both stars. These magnetic maps were used as an input of state-of-the-art 3D simulations of the stellar wind in order to model its interaction with the close-in planets. During my postdoc, I reported a potential detection of observational signatures of star-planet magnetic interactions in the AU Mic system, consistent in strength with the aforementioned stellar wind models.

• III. Characterising the atmosphere of transiting planets in high-resolution spectroscopy: The emergence of high-resolution near-infrared spectrographs opens a new era for the characterisation of planet atmosphere. In the end of my PhD, I started investigating how the large spectral domain of SPIRou could be used to recover the composition and physical properties of the atmosphere of transiting planets. Promising preliminary results on the hot Jupiter HD 189733 b has motivated the creation of a large consortium, at the French level, gathering both theoreticians and observers: the ATMOSPHERIX Collaboration. This consortium has already obtained 75 h of observations on several near-infrared spectrograph. We plan to release an open-source version of the data reduction code in the months to come.