First images from the James Webb Space Telescope: reaction of Michaël Gillon, astrophysicist

"These images are a powerful demonstration of the extraordinary instrumental potential of JWST. JWST is not just another space telescope, but a whole new window on the universe. Never before has man seen the heavens in this way. I was blown away by the image of thegalaxy cluster SMAC 0723 whose gravitational lensing effect allows us to see galaxies located at the edge of the observable Universe, as they were shortly after their birth. The images of the "Southern Ring Nebula" -a dying star that has ejected its outer layers- and of Stephan's "quintet -a compact group of galaxies- are equally splendid. But the image that touched me the most was the Carina Nebula, a "nursery" of stars that appears in all its splendor. This image of stars (and their planetary systems) in formation is simply overwhelming. It is a demonstration of the power of human intelligence, curiosity and ingenuity as well as the magnificence of the Universe.

And then, alongside these beautiful images, the NASA revealed measurements of the flux of two celestial objects taken at different wavelengths, what are called "spectra". The first is of a galaxy at the edge of the universe, and its accuracy and resolution are stunning. This spectrum demonstrates that JWST will be able to study the chemical composition of the most distant galaxies, and thus give us precious information on the first phases of the physico-chemical evolution of the Universe and of its large structures.

The second spectrum concerns me directly, because it is that of a giant exoplanet in the detection of which my team and I participated directly. This planet named WASP-96b "transits", that is to say that it passes in front of its star at each orbit. JWST observed one of these transits, and was able to measure with unprecedented precision and in a much wider spectral range than before the filtration of a tiny portion of the light emitted by the star in our direction by the planet's atmosphere, giving us valuable information about the chemical composition of this atmosphere. This spectrum leaves no doubt that JWST will revolutionize our understanding of exoplanets. Among other things, it should allow us to study the atmospheric properties of rocky - and even potentially habitable - exoplanets orbiting nearby small stars, including (and especially) the seven planets that my team and I discovered around the star TRAPPIST-1.

These images clearly mark the beginning of a new era for our study of the Universe and for understanding our place in it."

Michaël Gillon, astrophysicist, FNRS research fellow, director of the EXOTIC Lab of the Unité de Recherches en Astrobiologie of the University of Liege. Francqui Prize 2021.


Michael Gillon JWST

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