JWST Finds Methane and Silicon Monoxide on WASP-121b, Challenging 3,000°C Exoplanet Models
Updated
Updated · spacedaily.com · Jun 19
JWST Finds Methane and Silicon Monoxide on WASP-121b, Challenging 3,000°C Exoplanet Models
2 articles · Updated · spacedaily.com · Jun 19
Summary
Thomas Evans-Soma’s team used JWST’s NIRSpec to track WASP-121b through a full orbit and found abundant methane on the planet’s nightside alongside silicon monoxide on its dayside.
At roughly 3,000°C on the dayside, methane should not survive, and even the cooler nightside appears too hot to sustain it without constant replenishment from deeper atmospheric layers.
The team proposes strong vertical mixing on the nightside—upward winds lifting methane-rich gas from cooler depths—but says that mechanism was not predicted by standard ultra-hot Jupiter models, which emphasize horizontal circulation.
Silicon monoxide was also identified on the dayside, making WASP-121b the first planet with that molecule detected in any atmosphere and pointing to vaporized silicate material at observable altitudes.
Published in Nature Astronomy, the results suggest atmospheric models for ultra-hot Jupiters may need revision to explain how such planets maintain sharply different day-night chemistries.
Recent observations by the James Webb Space Telescope have revealed groundbreaking details about the atmosphere of the ultra-hot Jupiter WASP-121b. For the first time, scientists have conclusively detected silicon monoxide in a planetary atmosphere, alongside methane. These discoveries are remarkable because WASP-121b orbits extremely close to its star, causing dramatic temperature differences between its dayside and nightside. The presence of these molecules not only highlights the planet’s exotic chemistry but also provides important clues about how such gas giants form and evolve, reshaping our understanding of planetary atmospheres beyond our Solar System.