The cotton candy-like planet WASP-107 b has surprisingly low amounts of methane and a massive core. The findings, based on data from the James Webb Space Telescope, mark the first measurements of the mass of an exoplanet’s core and will likely inform future studies of planetary atmospheres and interiors, an important aspect of the search for habitable worlds outside our solar system. .

“Peering inside a planet hundreds of light-years away seems almost impossible, but when you know the mass, radius, composition of its atmosphere and how hot its interior is, you have everything you need to get an idea of ​​what it is. Lead author David Singh, Bloomberg Professor Emeritus of Earth and Planetary Sciences at Johns Hopkins University, talked about what’s inside and how heavy this core is. “We can now do this for many different gas planets in different systems.”

A published study Nature, showing that the planet contains a thousand times less methane than expected and that the core is 12 times larger than Earth’s. WASP-107 b, a giant planet surrounded by a cotton-soft, red-hot atmosphere, orbits a star about 200 light-years away. It is loose in nature: Earth is the size of Jupiter and its mass is only one-tenth that of that planet.

Although the planet contains methane, the building block of life on Earth, it is not considered habitable due to its proximity to its parent star and lack of a solid surface. However, it may hold important clues about the final stage of planetary evolution.

In a separate study published today NatureOther scientists also observed methane gas with the Webb telescope and provided similar information about the size and density of the planet.

“We want to look at planets in our solar system that are like gas giants with a lot of methane in their atmospheres,” Singh said. “This is where the story of WASP-107 b got really interesting, because we didn’t know why methane levels were so low.”

New measurements of methane show that the molecule breaks down into other compounds as it flows upward from the planet’s interior, interacting with a mixture of other chemicals and starlight in the upper atmosphere. The team also measured sulfur dioxide, water vapor, carbon dioxide and carbon monoxide and found that WASP-107 b contains more heavy elements than Uranus and Neptune.

Profiling the planet’s chemistry begins to reveal important pieces of the puzzle of how planetary atmospheres behave under extreme conditions, Singh said. His team will make similar observations of 25 more planets next year using the Webb telescope.

“We have never been able to study this mixing process in detail in the atmosphere of an exoplanet, so this will help us understand how these dynamic chemical reactions occur,” Singh said. “This is exactly what we need when we start looking at rocky planets and biomarker signatures.”

Scientists suggest that the planet’s extremely increased radius is the result of an internal heat source, said Zafar Rustamkulov, a Johns Hopkins planetary science doctoral student who led the study. By combining physical models of the atmosphere and interior with Webb’s data on WASP-107 b, the team elucidated how the planet’s thermodynamics affected its observed atmosphere.

“The planet has a hot core, and this heat source changes the chemistry of the gases more profoundly, but it also contributes to this strong, convective mixing coming from the inside,” Rustamkulov said. said. “We believe that this heat causes a change in the chemical composition of the gases, specifically destroying methane and producing increased amounts of carbon dioxide and carbon monoxide.”

The new findings also represent the clearest connection scientists have been able to establish between the exoplanet’s interior and its upper atmosphere, Rustamkulov said. Last year, the Webb telescope detected sulfur dioxide on another exoplanet called WASP-39 about 700 light-years away, providing the first evidence of an atmospheric compound formed by reactions caused by starlight.

The Johns Hopkins team is now focusing on what might sustain the hot core and expects forces similar to those that cause tides in Earth’s oceans to be at work. They plan to test whether the planet is being pulled by its star and how this might explain the high temperature of the core.