About Me

I am a permanent CNRS researcher based at Laboratoire d'Astrophysique de Marseille (France). In 2015, I spent one year at the European Southern Observatory in Chile, where I was co-instrument scientist of the VLT/SPHERE instrument. My research interest is the direct detection and characterisation of exoplanets, and the development of high-contrast instrumentation for this purpose. Direct imaging of young giant exoplanets has entered a new era thanks to the new generation of dedicated instruments that started operations on some of the largest ground-based telescopes in 2014-2015. I am part of the large consortium who has designed and built the SPHERE planet imager for the Very Large Telescope, and who is now using it to search for new giant planets around young stars in the solar neighbourhood with the SHINE survey.

Since 2017, I am also the PI of the ERC project HiRISE, which aims at coupling SPHERE with CRIRES+ to enable the characterization of young giant exoplanets at very high spectral resolution. The instrument was successfully installed at the VLT during the summer 2023 and has now entered regular science observations. HiRISE is part of a larger effort called SPHERE+, which proposes to develop an upgraded version of SPHERE.

Detection and characterisation of exoplanets

High-contrast imaging is the best method to detect the intrinsic light of giant exoplanets in the near-infrared around nearby young stars. Over the years, I have been involved in several large-scale observing programmes looking for new planets and brown dwarfs, such as the NaCo Large Programme (NaCo-LP) collaboration or the International Deep Planet Search (IDPS). The goal of these surveys was not only to detect and characterise new companions, but also to bring constraints on their population, such as their overall frequency and the distribution of their physical parameters. I had a central position in the 200-nights SPHERE/SHINE survey in the near-infrared, and during which we are observing several hundreds of stars covering a wide range of spectral type, age and distance. The survey has been conducted from 2015 to 2023 and has provided several high-impact results, including two new planets, HIP 65426 b and PDS 70 b. In 2020, I published the preliminary statistical analysis of the survey. I am also investing more and more time on the spectral characterization of known exoplanets and brown-dwarfs, in particular by exploring the possibilities of coupling high-contrast imaging with very high-resolution spectroscopy.

Development of high-contrast instrumentation

Detecting the faint signal of young exoplanets at very small angular separation from bright stars is extremely challenging. It requires a very specific instrumentation based on extreme adaptive optics, high-efficiency coronagraphs, fine wavefront control and advanced data analysis methods. I am working on several of these different aspects to develop new instrumentation dedicated to the detection and characterisation of exoplanets. I have participated in the design, development and testing of two instruments for the VLT. The first one is the Active Phasing Experiment (APE), a visitor instrument dedicated to the cophasing of segmented primary mirrors for Extremely Large Telescopes (ELTs), which was tested on-sky in 2008-2009. The second one is the new generation instrument SPHERE, which is entirely dedicated to the direct detection of young giant exoplanets. Since 2012, I am deputy instrument scientist of the SPHERE infrared dual-band imager and spectrograph (IRDIS), for which I have been responsible of the dual-band imaging (DBI) and long-slit spectroscopy (LSS) modes. I am now working on various methods to improve high-contrast imaging instrumentation, mainly the use of the ZELDA wavefront sensor to compensate the instrumental non-common path aberrations (NCPA) or for segment phasing, and the coupling of high-contrast imaging and high-dispersion spectroscopy (ERC HiRISE).

• © 2015-2021 Arthur Vigan