“He’s the one who did most of the work,” laughs Eric Lagadec, astrophysicist, assistant astronomer at the Lagrange laboratory of the Côte d'Azur Observatory. With one finger, he points to Guy Libourel. “No, no, I will be fierce about this, it’s teamwork”thunders, smiling, the “cosmochemist”. He also has a profession that makes you travel and dream: he searches for, studies, analyzes meteorites, to understand the solar system.
Collective work
With researchers from Mines Paris-PSL, Université Côte d'Azur, ENS de Lyon and CNRS, they “made” stardust. A first! “A superb first,” reacts Eric Lagadec, on the social network
Meteorites from the Sahara
It was in 2018 that they carried out the experiment. 15 days of preparation to set up the manipulation. And about three hours to create the stardust. “Usually, the first time, it never works. And there, bingo, it worked the first time,” jokes the cosmochemist. The “collective” collected 200 “studyable” grams of this precious material…
But concretely, how did they do it? Guy Libourel obtained meteorites. “I bought 5kg from a meteorite researcher, Luc Labenne”, he said. NWA chondrite meteorites from the Sahara. He still has a few pieces in one of his drawers. “For a philistine, it’s a stone”quips the researcher. “If we analyze the electromagnetic spectrum of the sun [qui est une étoile, Ndlr] and if we compare it with the chemical composition of a meteorite, apart from the light elements, it is the same composition”, deciphers Guy Libourel.
A tank, 5000 degrees… and the dust was
On D-Day, everything happened in Sophia-Antipolis, in the Min Paris premises. Mission: reproduce the stellar environment. “This dust forms around stars at the end of their life, like the sun in 5 billion years. These stars eject gas, which, as it moves away, cools, and following shocks, can become quite cold and dense to become solid: dust!”argues the astrophysicist.
They only used one “device”: a plasma torch. May the God of researchers forgive us for this trivial description: a sort of large cylindrical tank to which electrodes are “connected”. This is where the condensation will take place, thanks to temperatures raised to more than 5000 degrees at the top of the tank. “Cold” at the bottom… meaning only 1500 degrees.
The power of 40 kettles
Into this tank, scientists injected NWA meteorites from the Sahara reduced to dust. And this “dust” in contact with the extremely hot gases vaporized instantly, then condensed as the temperature dropped in the tank: to give another dust, that of stars. “It can be very black or whiter, the color is linked to the size of the grain and its chemical composition which can have either a reflective power or absorb light”, explains Guy Libourel. “ The power used is the equivalent of 40 kettles”, says Eric Lagadec.
“Stellar Factory”
Then came the long time of analyses. And publishing. Building on their successful experiment, the “collective” wishes to launch this operation at the national or international level. “We checked a first box, why not go further”, asks Guy Libourel. Create a “Stellar factory”.
1. This work is the result of a collaboration between Nice laboratories: PERSEE de Mines Paris-PSL specialized in energy storage and conversion, CRHEA (CNRS/Université Côte d'Azur) specialized in materials for devices photonics, optoelectronics, microelectronics, Géoazur (Université Côte d'Azur/Observatoire de la Côte d'Azur/CNRS, IRD) specialized in Earth Sciences, Lagrange (Université Côte d'Azur/Observatoire de la Côte d'Azur/CNRS ) specialized in astrophysics and the Lyonnais LGL-TPE laboratory (ENS de Lyon/CNRS/Université Lyon I/UJM) specialized in Earth Sciences. The scientist-researchers: Guy Libourel, Laurent Fulcheri, Vandad-Julien Rohani, Bernard Bourdon, Marwan Mokhtari, Clément Ganino and Eric Lagadec.
