In a significant breakthrough, two independent teams of researchers have unraveled the mystery behind the unusually puffy nature of the warm gas-giant exoplanet WASP-107 b. Utilizing data from NASA’s James Webb Space Telescope (JWST) and the Hubble Space Telescope, the teams have revealed new insights into the planet’s internal structure and atmospheric composition.

The findings, detailed in a report by NASA on Monday, indicate that the interior of WASP-107 b may be hotter and its core much more massive than previously estimated. This conclusion was drawn from the observed scarcity of methane (CH4) in the planet’s atmosphere.

“It is expected that the rise in temperature might be because of tidal heating caused by the planet’s non-circular orbit,” NASA stated.

Luis Welbanks from Arizona State University (ASU), in a paper published in *Nature*, explained, “Based on its radius, mass, age, and assumed internal temperature, we thought WASP-107 b had a very small, rocky core surrounded by a huge mass of hydrogen and helium. But it was hard to understand how such a small core could sweep up so much gas and then stop short of growing fully into a Jupiter-mass planet.”

NASA posted this on X and wrote, ""Puffy planets" like WASP-107 b, an exoplanet 200 light-years from Earth, are helping unravel an interstellar mystery—thanks to data from our orbiting 
@NASAWebb telescope."

By combining observations from Webb’s NIRCam (Near-Infrared Camera), Webb’s MIRI (Mid-Infrared Instrument), and Hubble’s WFC3 (Wide Field Camera 3), the team was able to construct a comprehensive spectrum of light absorbed by WASP-107 b’s atmosphere, spanning 0.8 to 12.2 microns.

Additionally, the researchers used Webb’s NIRSpec (Near-Infrared Spectrograph) to build an independent spectrum covering 2.7 to 5.2 microns. The high precision of the data allowed them to detect and measure the abundances of various molecules, including water vapor (H2O), methane (CH4), carbon dioxide (CO2), and ammonia (NH3).

David Sing, the lead author of a parallel study also published in *Nature*, stated, "The fact that we detected so little [methane], even though we did detect other carbon-bearing molecules, tells us that the interior of the planet must be significantly hotter than we thought.”

Previously, tidal heating was suggested as a possible explanation for the puffiness of WASP-107 b, but there was no concrete evidence to support this hypothesis until the recent results from Webb. With the determination that the planet has sufficient internal heat to significantly churn its atmosphere, the research teams recognized that the spectral data could provide a novel method for estimating the core size.

These groundbreaking observations not only shed light on the enigmatic characteristics of WASP-107 b but also open new avenues for understanding the formation and evolution of gas-giant exoplanets.