The atmospheric composition of the hot gas giant exoplanet WASP-39 b has been revealed by NASA’s James Webb Space Telescope. This graphic shows four transmission spectra from three of Webb’s instruments operated in four instrument modes. At upper left, data from NIRISS shows fingerprints of potassium (K), water (H2O), and carbon monoxide (CO). At upper right, data from NIRCam shows a prominent water signature. At lower left, data from NIRSpec indicates water, sulfur dioxide (SO2), carbon dioxide (CO2), and carbon monoxide (CO). At lower right, additional NIRSpec data reveals all of these molecules as well as sodium (Na). Credits: NASA, ESA, CSA, J. Olmsted (STScI)
Key Points:
- The James Webb telescope has detected multiple molecular and chemical ingredients in the atmosphere of an exoplanet.
- For the first time, the telescope detected sulfur dioxide.
- The data gives scientists a better idea of how the exoplanet, and maybe others, formed.
NASA's James Webb Telescope has revealed new findings of an exoplanet’s molecular and chemical profiles. The new readings reveal a full menu of atoms and molecules around the planet's atmosphere, and even signs of active chemistry and clouds.
The suite of discoveries is detailed in a set of five new scientific papers, three of which are in press and two of which are under review.
Setting the telescope’s sights on WASP-39 b, a “hot Saturn”, Webb detected sulfur dioxide (SO2) in the exoplanet’s atmosphere—for the first time. SO2 is produced from chemical reactions triggered by high-energy light from the planet’s parent star.
"This is the first time we see concrete evidence of photochemistry – chemical reactions initiated by energetic stellar light – on exoplanets," said Shang-Min Tsai, a researcher at the University of Oxford and lead author of the paper explaining the origin of sulfur dioxide in WASP-39 b's atmosphere.
Other atmospheric constituents detected by the Webb telescope include sodium (Na), potassium (K), and water vapor (H2O), confirming previous space and ground-based telescope observations as well as finding additional fingerprints of water, at these longer wavelengths, that haven’t been seen before.
Webb also saw carbon dioxide (CO2) at higher resolution, providing twice as much data as reported from its previous observations. Meanwhile, carbon monoxide (CO) was detected, but obvious signatures of both methane (CH4) and hydrogen sulfide (H2S) were absent from the Webb data. If present, these molecules occur at very low levels.
WASP-39 b’s chemical inventory suggests a history of smashups and mergers of smaller bodies called planetesimals to create an eventual goliath of a planet.
Having such a complete roster of chemical ingredients in an exoplanet atmosphere gives scientists a glimpse of the abundance of different elements in relation to each other. That, in turn, provides insight into how this planet—and perhaps others—formed out of the disk of gas and dust surrounding the parent star in its younger years.
“We had predicted what [the telescope] would show us, but it was more precise, more diverse, and more beautiful than I actually believed it would be,” said Hannah Wakeford, an astrophysicist at the University of Bristol.
Information provided by NASA.