James Webb Space Telescope Feed Post

NASA’s Webb Identifies Methane In an Exoplanet’s Atmosphere

Catch a whiff of this. Webb made a definitive detection of methane gas in the atmosphere of “warm Jupiter” WASP-80 b. Like the name suggests, the planet is similar in size to Jupiter, but with much warmer temperatures. At 163 light-years away, WASP-80 b is very far from us. But it orbits very close to its parent star, with a year of only 3 Earth-days! To study the planet’s atmosphere, Webb observed how the combined light from the star and the planet was affected as WASP-80 b moved in front of and behind its star. The science team then created spectra, or measurements of how much light was blocked or emitted by the planet's atmosphere at different wavelengths. These measurements inform scientists of the chemical composition of the exoplanet, as well as what that tells us about the planet’s birth, growth and evolution. Hear directly from the researchers about their discovery in the latest Webb blog post: blogs.nasa.gov/webb/2023/11/22/nasas-webb-identifies-meth... This image: The measured transit spectrum (top) and eclipse spectrum (bottom) of WASP-80 b from NIRCam’s slitless spectroscopy mode on NASA’s James Webb Space Telescope. In both spectra, there is clear evidence for absorption from water and methane whose contributions are indicated with colored contours. During a transit, the planet passes in front of the star, and in a transit spectrum, the presence of molecules makes the planet’s atmosphere block more light at certain colors, causing a deeper dimming at those wavelengths. During an eclipse, the planet passes behind the star, and in this eclipse spectrum, molecules absorb some of the planet’s emitted light at specific colors, leading to a smaller dip in brightness during the eclipse compared to a transit. Image Credit: BAERI/NASA/Taylor Bell. Image description: Graphic titled “Atmospheric Composition, WASP-80 b. Data from Webb’s NIRCam instrument.” Next is a short blurb: “Webb observed the warm gas giant exoplanet WASP-80 b using two different methods. Its spectra (below) shows a clear detection of methane gas throughout the planet’s atmosphere.” Then there are two graphs. The first graph generally slopes down, while the second graph slopes up. Their data were taken using the transit method for the top graph and the eclipse method for the bottom graph. The x-axis for both is labeled “Wavelength of light (microns).” It runs from 2.4 to 4.0 microns in increments of 0.2. The y-axis for the transit graph is labeled “Amount of starlight blocked,” and it runs from 2.88% to 3.00%. The eclipse graph’s y-axis is “Amount of planetary light emitted” and goes from 0.00% to 0.12%. Both graphs are plotted with white dots that have error bars running through them. There are clear signatures of water vapor (highlighted in green) and methane (highlighted in purple). Image & Description by NASA