My research focuses on Exoplanets and Disks imaging mainly with the instrument SPHERE at the Very Large Telescope in Chile. My Ph.D. aims to better understand planet formation by peering into the architecture of planetary systems. In practice, I characterize known exoplanets (orbital motion, spectral emission), and look for additional exoplanets. In addition, I am interested in debris disks, characterizing their emission and morphology. I am part of the SPHERE and SPHERE+ consortia. In the SPHERE+ consortium, I work in the astro simulations group, in particular on the design of the medium resolution spectrograph. Therefore, my Ph.D. is strongly based on both observational and instrumental aspects.

After seven years of operations, SPHERE is one of the most efficient disks and exoplanet imagers worldwide. As the signal extraction and data processing of faint exoplanets or disks from observations requires a deep understanding of the instrument, it is highly valuable to combine instrumental studies and astrophysical interpretation.

From an observation perspective, my main objects of interest are young and nearby systems. From a few millions years old as the protoplanetary disks which are the birth places where exoplanets form, to about twenty million year old when the gas in the system has vanished but the putative exoplanets or debris disks emit still enough light in the near infrared to be observed. At a few giga year old, direct-imaging observations have poor sensitivity and can detect only companions close to the regime of brown dwarves to date. Yet, observing old systems can be mandatory if one wants to combine direct-imaging observations with radial velocity measurements sensitive to small planets, as super-Earths. Old stars are more stable, increasing a lot the sensitivity of radial velocity measurements. That’s why in one of my Ph.D. projects, I target stars between 500 Myr and 10 Gyr.


[HD 95086 (young system at 86 pc)  versus  GJ 229 (old system at 6 pc)]

I have started to work in this field of direct imaging and in particular with the instrument SPHERE during my research internships in master, the first one dating back to 2019.

An observer in astrophysics wears several hats: from writing the proposal and making the observation blocks, to the data acquisition, processing and analysis. I enjoy experiencing these different jobs. In particular,

  • In 2019, I had the chance to go at Paranal to observe with SPHERE in visitor mode. I submitted ESO proposals with SPHERE, one being accepted and executed in summer 2022. In Fall 2023, I have submitted as PI several proposals, using the facilities VLT/SPHERE, JWST, HST and LBT/SHARK-NIR+LMIRCam. My two proposals with LBT/SHARK-NIR+LMIRCam and VLT/SPHERE were accepted, and the one using JWST submitted as co-PI.

  • During a master internship at the Max-Planck Institute for Astronomy in Germany, I investigated baseline to cutting-edge image processing techniques. The goal was to retrieve directly-imaged protoplanetary disks in near infrared to look for proto-exoplanets creating the observed substructures inside the disks. This project was carried out in the context of the paper from Assenssio-Torres et al. 2021.


    • PDS 70 processed with the Mayo pipeline described in Pairet et al. 2020.

  • I led an in-depth direct-imaging and spectroscopic characterization on the young exoplanetary system HD 95086, recently published (Desgrange et al. 2022).


Overview of the HD 95086 system. This is a composite image with in pink the outer belt resolved by ALMA (Su et al. 2017) and in yellow the exoplanet b seen by VLT/SPHERE (Chauvin et al. 2018).
Figure from Desgrange et al. 2022.

After acquiring, processing and analyzing observation, I chose to experience the other side of the mirror: instrumentation. During my master’s thesis, I looked into instrumental limitations from polarization effects known as the Goos-Hänchen and Imbert-Fedorov effects. I compared theoretical predictions to experiments on the optical high-contrast imaging testbed Très Haute Dynamique 2 (THD 2) bench at the Observatoire de Paris.


Polarization effects on the THD 2 bench



During my Ph.D., I continue to develop expertise both in high-contrast imaging observations and instrumentation.

In observations, my two main projects currently are

  • first, a survey coupling different detection methods to have the more complete view of the exoplanetary systems investigated, and
  • second, the characterization of a complex and enigmatic debris disk.

In instrumentation, I am doing in particular molecular mapping simulations to test different designs to upgrade the low resolution integral field spectrograph (IFS) of SPHERE into a medium resolution IFS.

I am part of the consortia SPHERE, SPHERE+ and SHARK-NIR.