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Philippe Stée elected president of the Paris Observatory – PSL

2 février 2026  Philippe Stée elected president of the Paris Observatory – PSL

On Friday, January 30, 2026, Philippe Stée was elected President of the Observatoire de Paris - PSL at a plenary meeting of the institution. On March 13, he will succeed Fabienne Casoli at the head of the institution founded in 1667 and now part of PSL University.

Born in 1968, astrophysicist Philippe Stée is a research director at the CNRS. He conducts his scientific activities at the Lagrange Laboratory of the Côte d’Azur Observatory, which he directed from 2016 to 2023.

His research focuses on two complementary areas : the physics of hot stars and circumstellar disks, and the development and use of optical interferometry techniques, fields in which he has distinguished himself internationally.

His research relies on the use of large optical and infrared interferometry instruments, in particular AMBER, MIDI, and MATISSE on ESO’s Very Large Telescope Interferometer (VLTI) in Chile, as well as the VEGA instrument installed at the focus of the CHARA interferometric network on Mount Wilson (United States), for which he was co-investigator. In particular, he developed a numerical code simulating the circumstellar environment of hot active stars, highlighting their near-critical rotation which, combined with the radiative pressure of the stellar wind, forms an ejection disk as opposed to the accretion disks that form around young stars.

Beyond his scientific activities, Philippe Stée has been heavily involved in collective and governance responsibilities. His experience as director of the Lagrange Laboratory and scientific delegate at the CNRS’s National Institute for Sciences of the Universe (INSU) has led him to manage multidisciplinary teams, oversee major international projects, and lead organizational transformations in a highly demanding scientific environment.

Philippe Stée will take up his position on March 13, 2026, for a five-year term.