Scientists studying the puffed-up atmosphere of exoplanet WASP-107b say the advanced instruments of NASA’s James Webb Space Telescope are helping them create a three-dimensional map of the unusual atmosphere in stunning detail.
Originally spotted in 2017 by researchers from the Wide Angle Search for Planets (WASP-South) international consortium, the warm-Neptune gas giant has perplexed astronomers due to its puffy atmosphere.
“Our previous findings showed that WASP-107b is extraordinarily puffed up, almost as if the planet had popped like a kernel of popcorn under its own heat,” explained study co-author Luis Welbanks, a 51 Pegasi b Fellow at Arizona State University’s School of Earth and Space Exploration.
WASP-107b orbits a relatively small, cool star roughly 210 light years from Earth. The planet also has about 80% of the volume of Jupiter but only 10% of its mass, making it an unusual find for exoplanet hunters.
Due to its proximity to its host star, WASP-107b completes an orbit every 5.72 days. It is also tidally locked, meaning half of the planet is in permanent sunlight while the other is in permanent darkness. WASP-107b made headlines in 2023 when researchers detected water vapor, sand clouds, and sulfur dioxide in its atmosphere.
Led by Matthew Murphy, a graduate student at the University of Arizona’s Steward Observatory, the research team trained JWST’s robust suite of instruments on the planet’s atmosphere. Several observations were conducted when the planet passed between Earth and its host star, allowing scientists to measure and characterize the starlight as it passed through its atmosphere and create a three-dimensional atmospheric map.
“With JWST, we are getting a clearer picture of what’s happening in its atmosphere in three dimensions, and it turns out there’s even more to munch on!” said Welbanks.
Perhaps the team’s most significant finding is a pronounced asymmetry in the atmosphere between the eastern and western halves of the planet. According to the study, this variance “suggests differences in the properties between the two sides of the exoplanet.”
“The source of this asymmetry is intriguing,” said Associate Professor Michael Line from Arizona State University, who contributed to the research. “While our initial analysis suggests that the asymmetries may be due to one limb of the planet being more cloudy than the other, this could also be linked to how heat is transported across the planet’s atmosphere.”
“It’s as if one side of WASP-107b is cooking faster than the other!” he added.
Before JWST, this finding would have been virtually impossible. However, the sophisticated nature of the telescope’s instruments allowed the researchers to isolate and examine the light spectrum data from the eastern and western edges of the planet’s atmosphere separately. According to the researchers, this feat has never been achieved in this detail.
“The high precision of JWST’s instruments is like having a magnifying glass for planets,” said Welbanks. “We can now look at specific processes happening on each side of WASP-107b’s atmosphere, giving us valuable insights into how climate works in these extreme conditions.”
Murphy agreed, noting the difficulty in studying ‘intermediate’ planets whose size rests somewhere between the planets in our solar system and the hottest, most massive exoplanets ever discovered has resulted in very little data.
“Traditionally, our observing techniques don’t work as well for these intermediate planets, so there’s been a lot of exciting open questions that we can finally start to answer,” he said. “For example, some of our models told us that a planet like WASP-107b shouldn’t have this asymmetry at all – so we’re already learning something new.”
The study “Evidence for morning-to-evening limb asymmetry on the cool low-density exoplanet WASP-107 b” was published in Nature Astronomy.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.