JWST Creates First Chemical Profile of Exoplanet Atmosphere • The Register

The James Webb Space Telescope keeps opening the world up to new science. This time, it’s the first molecular and chemical profile of an exoplanet’s atmosphere, complete with evidence of active photochemical reactions.

As part of the full chemical profile of exoplanet Wasp 39b — where Webb found clear evidence of carbon dioxide in an exoplanet atmosphere earlier this summer — NASA said the telescope picked up more CO₂as well as carbon monoxide, sodium, potassium and water vapor.

Sulfur dioxide (SO₂) was also discovered, which according to Oxford University researcher Shang-Min Tsai is concrete evidence of photochemistry – chemical reactions triggered by light hitting a planet’s atmosphere. For example, the earth’s ozone layer was created by photochemistry.

“I see this as a really promising perspective to advance our understanding of exoplanet atmospheres,” Tsai said.

As in the detection of CO₂ In Wasp 39b’s atmosphere, the JWST relied on the planet’s transit around its star and how chemicals in its atmosphere affected the wavelengths of light captured by the telescope. When light hits different elements, they reflect different wavelengths, which the JWST can detect with extreme precision.

Three of Webb’s four scientific instruments were used to create Wasp 39b’s atmospheric profile: the Near-Infrared Image and Slitless Spectrograph (NIRISS), the Near-Infrared Camera (NIRCam), and the Near-Infrared Spectrograph (NIRSpec), which was used in two configurations.

The full atmospheric profile of Wasp 39b as recorded by the JWST

Why Atmospheric Profiles Matter

Great: We know what’s in the atmosphere of a gas giant eight times closer to its star than Mercury is to the Sun. So?

For one, the list of chemicals in an atmosphere provides researchers with ratios between them, which NASA says is a fundamental part of determining planet formation. Kazumasa Ohno, an exoplanet researcher at the University of California at Santa Cruz who worked with the JWST data, said Wasp 39b’s chemical composition gives researchers some clues.

“The abundance of sulphur [relative to] Hydrogen indicated that the planet was likely experiencing a significant accumulation of planetesimals,” Ohno said. “The data also show that the oxygen is much more abundant than the carbon in the atmosphere. This may indicate that WASP-39 b originally formed far from the host star.”

The discovery of photochemistry also led to another first, NASA said, where “scientists apply computer models of photochemistry to data that require a full explanation of this physics.”

It was this application that NASA said led to improvements in its modeling capabilities that “will help build the technological know-how to interpret potential signs of habitability on other exoplanets.”

University of Bristol astrophysicist Hannah Wakeford said the Webb team predicted how well the observatory would work, “but it was more precise, diverse and beautiful than I expected.”

With a long, hard look at Wasp 39b out of the way, and Webb’s instruments performing above expectations, NASA is poised for additional exoplanet surveys. It could start looking at rockier worlds like those in the TRAPPIST-1 system – some of which lie in the star’s habitable zone.

Laura Flagg, a researcher at Cornell University and a member of the international Webb team, said the future looks bright for JWST. “We will be able to see the full picture of exoplanet atmospheres… It’s incredibly exciting to know that everything is being rewritten.” ®