Those Bordelais who exploit what the James Webb telescope “sees”.

These questions are so elusive so far, people from Bordeaux are working to answer them. And they are at the forefront, being among the researchers chosen to benefit as a priority from the results of the James Webb Space Telescope (JWST), which will be launched at the end of 2021. With the results already.

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These questions are so elusive so far, people from Bordeaux are working to answer them. And they are at the forefront, being among the researchers chosen to benefit as a priority from the results of the James Webb Space Telescope (JWST), which will be launched at the end of 2021. With the results already.

Jeremy Leconte work in Purdue Astrophysical LaboratoryMixed unit CNRSPurdue University. It is part of a global consortium of 300 exoplanet scientists selected to obtain the first JWST observations under the Early Launch Science (ERS) program.

Why this honor? “We don’t ‘see’ the exoplanet itself: only that the light of its star diminishes as it passes in front of it,” explains the 37-year-old researcher. And when it passes in front of it, its atmosphere, depending on the particles it contains, blocks this or that wavelength of light emitted by the star. »

CO₂, in infrared we find this “signature”. “Compared to Hubble, it is precisely these spectral ranges that promise JWST ahead. Therefore, our request made it possible to verify that the telescope is licensed to do what it was designed to do. And from first observation, we saw a huge signal on WASP-39b, in the constellation Virgo, where we expected find it.”

Results fell on July 12th. The Union of Scientists has been “reducing” this data one by one and quickly Found consistent results. who was the subjectPublished in the journal “Nature” on September 2.

“We’ve focused our communication on having a CO₂which we expected. But paradoxically, we were more excited about the presence of another molecule that wasn’t necessarily expected: sulfur dioxide (SO).₂). Yes, it smells like a rotten egg on the WASP-39. “But we’re not nearly there: it’s several thousand degrees. On the one hand, this discovery allows us to see in action, for the first time, photochemical phenomena: SO₂ WASP-39b forms the Earth’s equivalent of the ozone layer, as photons scatter oxygen molecules (O₂) of our atmosphere, which combine into the ozone layer (0₃). »

As on Earth…but there is no plan on the comet. Exoplanets are known to the general public because they would likely host life, if it existed elsewhere. “But that’s not what motivates me,” Jeremy Leconte said. “Wanting so much to find life, we risk seeing bacteria everywhere.”

We also find the beginnings of life far beyond planets. This is part of Joëlle Mascetti, which also benefits from the ERS program. You can meet her on the chemistry side of campus, atInstitute of Molecular Sciencesanother joint UB-CNRS unit.

“You don’t have to imagine it’s like organic chemistry, with benches and balloons and things that explode,” warns the sixty-year-old. Replete with cables and tubes, the Molecular Spectroscopy Group’s laboratory looks like a mad inventor’s lair. “Here, we’re trying to reproduce the conditions that prevail in interstellar space: a very high vacuum and 10 degrees Kelvin (-263.15 degrees Celsius).”

The spatial “void” is not completely empty. When stars die and explode, they throw out all the atoms they produced through a nuclear reaction. Astrochemistry studies how they recombine “at low energy” in dust clouds that are nebulae.

In her laboratory, Joëlle Mascetti simulates these reactions and analyzes them with infrared spectroscopy: “In the interstellar ice, we can observe the formation of complex molecules that are the first building blocks of life,” the researcher continues. “Among these, I am interested in polycyclic aromatic hydrocarbons, whose first observations from JWST highlighted their presence in the Orion Nebula thanks to their infrared signature.”