File:Exoplanet WASP-39 b (Transmission Spectra) (52517481568).jpg

Webb has revealed an exoplanet atmosphere as never seen before!

The telescope has revisited gas giant WASP-39 b to give us the first molecular and chemical profile of an exoplanet’s atmosphere, revealing the presence of water, sulfur dioxide, carbon monoxide, sodium and potassium, as well as signs of clouds. This builds on Webb’s initial look at the planet back in August, which showed the first clear evidence of carbon dioxide in a planet outside our solar system. The latest findings bode well for Webb’s capability to investigate all types of exoplanets, including the atmospheres of smaller, rocky planets like those in the TRAPPIST-1 system.

We learn about exoplanet atmospheres by breaking their light into components and creating spectra. Think of a spectrum as a barcode. Elements and molecules have characteristic signatures in that “barcode” we can read.

This planet is what is known as a “hot Saturn” — a planet about as massive as Saturn but eight times closer in orbit around its star than Mercury is around the Sun. The data shown here is taken from 3 of Webb’s science instruments. Together, they mark a series of firsts in science, including the first detection of sulfur dioxide in an exoplanet atmosphere. This, in turn, is the first concrete evidence of photochemistry — chemical reactions initiated by high-energy light, which are fundamental to life on Earth — on an exoplanet. Understanding the ratio of different elements in relation to each other also offers clues as to how the planet was formed.

Want to see the data in more detail and learn more? Head to the feature here: www.nasa.gov/feature/goddard/2022/nasa-s-webb-reveals-an-...

Download different versions of this graphic (and individual spectra) here: webbtelescope.org/contents/media/images/2022/060/01GJ3Q66...

Image credit: Credits: NASA, ESA, CSA, J. Olmsted (STScI)

Image description:

Graphic of the atmospheric composition of exoplanet WASP-39 b, showing 2 graphs and a background illustration of the planet and its star.

(Left side) The top graph shows data from Webb’s NIRISS instrument, the bottom graph data from NIRSpec. Both graphs show the amount of light blocked on the y axis versus wavelength of light on the x axis. The y axes range from 2.00 percent (less light blocked) to 2.35 percent (more light blocked). The x axes range from less than 0.1 microns to 5.5 microns. Data points are plotted as white circles with gray error bars. A curvy blue line represents a best-fit model. The NIRISS data covers a range of about 0.5 to 3.0 microns and highlights the signatures of potassium, water and carbon monoxide in semi-transparent bars of varying colors. Potassium is gray, water is blue, and carbon monoxide is red. The NIRSpec data covers a range of about 2.5 to 5.25 microns. It highlights water and carbon monoxide in addition to sulfur dioxide in green and carbon dioxide in yellow.

(Right side)