Webb telescope helps solve longstanding mystery of why some planets appear so “puffy”
Astronomers believe they’ve solved a peculiar and well-established cosmic mystery, NASA announced this week. Mainly using observations from the James Webb Space Telescope, two groups of researchers may have discovered what causes certain planets to appear “puffy” or inflated far beyond the sizes their remarkably low densities would suggest.
It’s a phenomenon that seems to boil down to the surprising internal composition of exoplanets like WASP-107b, a “warm Neptune” gas giant identified in 2017 that orbits a star about 200 light-years from Earth. Although scientists have already identified thousands of low-density exoplanets, this one was different from the “hot Jupiters” and even the uncommon “hot Neptunes” studied before.
Astronomers looked at the makeup of WASP-107b in hopes of understanding how it could be so massive while weighing so little, since they assumed based on features like its size and the distance from its star that it was cooler internally than it turned out to be.
WASP-193b, which was discovered last year and also noted for its extraordinarily low density.
While there was no evidence-based explanation for the puffiness of larger, hotter exoplanets, either, scientists said that WASP-107b was particularly hard to explain, because it doesn’t glean enough energy from the star it orbits for the gases composing it to inflate so much. But new data from Webb, combined with older data from the Hubble Space Telescope, revealed another cause for its expansion.
The telescope observations detected only a tiny fraction of the methane gas that astronomers expected to find in WASP-107b’s atmosphere, which “tells us that the interior of the planet must be significantly hotter than we thought,” said David Sing of Johns Hopkins University, who led a second new study on WASP-107b.
That supports a theory astronomers previously proposed about why WASP-107b is “puffy,” suggesting that a process called tidal heating is responsible for both its warmer internal temperature and inflated size. Learning about the atmosphere of WASP-107b may also give crucial insight into dozens of other “puffy” low-density planets and what makes them expand, potentially helping to clear up what NASA called a “longstanding mystery in exoplanet science.”
Emily Mae Czachor
Source: cbsnews.com