The James Webb Space Telescope has for the first time detected the presence of CO2 in the atmosphere of an exoplanet, a planet outside our solar system, demonstrating its enormous potential and exciting scientists for further observations.
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The planet in question is a hot gas giant where we know life is impossible, but the discovery supports the idea that such observations could be made on rocky planets as well — with the ultimate goal of determining whether one of them harbors favorable conditions. for life.
“For me, this opens the door to future studies of super-Earths, Earths,” Pierre-Olivier Lugage, astrophysicist at the Atomic Energy Commission (CEA), told AFP on Thursday. and is one of several co-authors of the work, which will be published in the scientific journal Nature.
“My first reaction: Wow, we have a chance to detect the atmospheres of Earth-sized planets,” Natalie Batalha, a professor of astrophysics at the University of California, Santa Cruz, commented on Twitter.
By detecting CO2, NASA said it could learn more about the formation of the planet, named WASP-39 b and discovered in 2011. Located 700 light-years away, it is a quarter of Jupiter’s mass and the closest to its Sun.
At a time when scientists are still assessing the telescope’s capabilities, it was chosen because several criteria made it easy to monitor, and it revealed its first images within two months.
WASP-39 b passes in front of its Sun very regularly (it orbits it in four days), and its atmosphere is stretched.
For his observations, James Webb uses the transit method: when the planet passes in front of its star, he captures the resulting slight variation in luminosity.
He then analyzed the light “filtered” through the planet’s atmosphere. Different molecules in the atmosphere leave specific signatures that help determine their composition.
The Hubble and Spitzer telescopes had already detected water vapor, sodium and potassium in the planet’s atmosphere, but James Webb was able to go further thanks to his extraordinary sensitivity to infrared.
In a NASA press release, Zafar Rustamkulov of Johns Hopkins University described his feelings when the presence of CO2 became apparent: “It was a special moment, a milestone in the science of exoplanets.”