James Webb Finds Carbon Dioxide in Exoplanet Atmosphere

For the first time in the history of exoplanet observations, NASA's James Webb Space Telescope has detected clear traces of carbon dioxide in the atmosphere of a planet outside the solar system. This planet is a Sun-like star 700 light-years away, called WASP-39 b.

WASP-39 b is a hot gas giant with a mass about a quarter of that of Jupiter (similar to Saturn) and a diameter 1.3 times larger than Jupiter, located 700 light years away. Unlike the gas giants in our solar system, the planet is very close to its star, eight times closer than Mercury is to the sun, so its atmosphere is heated to 900 degrees centigrade.

Previous observations from other telescopes, including NASA's Hubble and Spitzer space telescopes, have shown the presence of water vapour, sodium and potassium in the planet's atmosphere. Now Webb's unrivalled infrared sensitivity has confirmed the presence of carbon dioxide in the planet's atmosphere.

According to NASA, determining the chemical composition of planets' atmospheres is important because it provides data on their origins and how they evolved. Mike Lyne of Arizona State University, a member of the research team said:

Carbon dioxide molecules are sensitive tracers of the story of planet formation. By measuring this carbon dioxide feature, we can determine how much solid versus how much gaseous material was used to form this gas giant planet. In the coming decade, JWST will make this measurement for a variety of planets, providing insight into the details of how planets form and the uniqueness of our own solar system.