New observations suggest that the “super-chubby” exoplanet is spewing a lot of helium into space – and may be in the process of losing much of its atmosphere.
A large plume of helium gas was seen evaporating from the giant planet, known as WASP-107b, according to a study based on observations from a space telescope. James Webb Space Telescope (JWST).
Planet puff ball
WASP-107b was discovered in 2017 near a star approximately 210 light-years from Earth. (For comparison, the closest planets to us are about 4 light years away.) WASP-107b is almost the same size as Jupiteris 94% of the diameter of the gas giant, but its mass is only 12% of the mass of Jupiter. Its extremely low density and large size classify WASP-107b as a “super plump” exoplanet.
Besides its unusual density, WASP-107b is in an interesting location: it is seven times closer to its star than Mercury is to the Sun. In contrast, in the Earth's vicinity, rocky planets are closer to the Sun, and gas giants such as Jupiter are further away. This means scientists must come up with models to explain the difference.
They believe that WASP-107b, like Jupiter and Saturn, formed much further from its star, but something in the system – perhaps another planet – caused WASP-107b to migrate closer to its star over time.
“WASP-107c, which was much further away than WASP-107b, may have played a role in this migration,” study co-author. Caroline Piolet-Goraebexoplanet researcher, now at the University of Chicago, who received her Ph.D. at the University of Montreal in 2024, the release said.
The researchers explained that once the planet got close enough to its star, the intense heat in its new orbit began to destroy the exoplanet's gaseous atmosphere. New JWST observations confirmed the extent of the damage: the powerful telescope spotted a helium cloud in the exoplanet's atmosphere, passing in front of the system's host star about 1.5 hours before WASP-107b itself.
Researchers have discovered several elements in WASP-107b's atmosphere that reveal additional clues about the planet's complex history. For example, the planet had more oxygen in its atmosphere than would be predicted if it formed close to its star, providing more evidence that its migration was relatively recent.
JWST also detected water in the planet's atmosphere, confirming previous observations from Hubble Space Telescope — along with traces of carbon monoxide, carbon dioxide and ammonia. But methane, which was assumed to be part of the planet's atmosphere due to its chemical composition, was strangely absent.
Because JWST's instruments are sensitive enough to detect methane from afar, the researchers speculate that other low-methane gases must instead have been pulled up from deep in the planet's atmosphere due to “vigorous vertical mixing” caused by the star's heat, Piaule-Goraeb added.
Although planets like Earth also experience some atmospheric loss, it is not that extreme. Studying worlds like WASP-107b could help us understand how atmospheric escape occurs on planets like Venus. lost water over thousands of yearsthe research team said in a post. statement from the University of Geneva.
