The James Webb Space Telescope (JWST) has just scored another first: It reveals an exoplanet’s atmosphere as never seen before. For this occasion, Webb shows us the first molecular and chemical profile in the skies of a distant world, beyond the solar system.

(The James Webb Space Telescope (JWST) has just scored another first: the first molecular and chemical profile in the skies of a distant world, beyond the solar system.) (Credit NASA).
Earlier, NASA’s Spitzer and Hubble Space Telescope have revealed ingredients isolated from the atmosphere of this scorching planet dubbed WASP-39 b. Now, the new JWST readings provide a full menu of atoms, molecules, and even signs of chemical activity and clouds.

WASP-39 b is a hot exoplanet 700 light-years away, it orbits its star in a smaller orbit than Mercury, but it is almost as massive as Saturn. Thanks to the telescope’s highly sensitive instrument suite, he trained in the atmosphere of WASP-39 b. Once again he makes it clear to us that his abilities are not only based on data that translates as beautiful and extremely detailed images, but also on spectra. And the spectra, humbly, bring us some of the most intriguing discoveries in astronomy.

The findings have been collected in 5 scientific articles, three of which will be published soon, and two are under review. According to NASA collaborators , among the unprecedented revelations is the first detection in an exoplanet’s atmosphere of sulfur dioxide (SO2), a molecule produced from chemical reactions triggered by high-energy light from the star. hostess of this planet. On Earth, the protective ozone layer in the upper atmosphere is created in a similar way.

“Other atmospheric constituents detected by the Webb telescope are sodium (Na), potassium (K) and water vapor (H2O), confirming previous observations from space and ground-based telescopes, as well as the finding of additional signs of water, in these longer wavelengths, which have not been seen before.”

This plot shows four transmission spectra of three of Webb’s instruments operated in four of the instrument’s modes. At the top left, data from the NIRISS instrument shows signals for potassium (K), water (H2O), and carbon monoxide (CO). At the top right, the NIRCam data shows a prominent water signal. At the bottom left, NIRSpec data indicates water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO). At the bottom right, additional NIRSpec data reveals all of these molecules, as well as sodium (Na). (Credits: NASA, ESA, CSA, J. Olmsted (STScI)).
“This is the first time we’ve seen concrete evidence of photochemical activity — chemical reactions initiated by energetic starlight — on exoplanets, ” Shang-Min Tsai , a researcher at the University of Oxford in the UK and lead author of the paper, said in a statement. which explains the origin of sulfur dioxide in the atmosphere of WASP-39 b. “I see this as a really promising prospect for advancing with [this mission] our understanding of the atmosphere of exoplanets.”

Earlier the James Webb had marked a first by detecting carbon dioxide (CO2 ) for the first time in WASP-39 b. For this occasion, the new telescope took another look at CO2, only with a higher resolution, providing twice as much data as reported in its previous observations. “Meanwhile, carbon monoxide (CO) was detected, but obvious traces of methane (CH4) and hydrogen sulfide (H2S) were absent from Webb’s data. If present, these molecules would occur at very low levels.”

By using a precise subtraction method, known as transmission spectroscopy, researchers can measure the content of an exoplanet’s atmosphere. Transmission spectroscopy with Webb works as follows: You will first look at the star itself to get its spectrum. Next, Webb will wait until the exoplanet passes in front of its star, and then he will measure another spectrum.

“We had predicted what [the telescope] would show us, but this was more accurate, more diverse and more beautiful than I really thought it would be,” said Hannah Wakeford , an astrophysicist at the University of Bristol in the UK who researches the exoplanet atmospheres.