The James Webb Telescope reveals new details about WASP-107b, an inflated exoplanet with a surprising atmosphere. (University of Montreal)
He exoplanet WASP-107b It has been an object of intrigue for astronomers since its discovery. With a mass less than a tenth that of Jupiter, but almost equivalent in size, this gas giant has baffled researchers because of its inflated, spongy nature.
Discovered in 2017 by a team led by DR Anderson through the WASP-South telescope, over the years it has earned the nickname of “pochoclo or popcorn planet” due to its low density and swollen appearance, as if it had “exploded” under its own heat.
However, thanks to the latest advances provided by the James Webb Space Telescope (JWST), the scientific community has been able to obtain new details about the structure and atmosphere of this exoplanet, revealing crucial data about its formation and internal dynamics.
Artist’s illustration of exoplanet WASP-107 b in orbit around its host star. This illustration is based on transit observations made with the NIRCam instrument on NASA’s James Webb Space Telescope, as well as other space and ground-based telescopes. (Credit: Rachel Amaro, University of Arizona)
WASP-107b orbits a star at a distance of only 8 million kilometers, a seventh of the distance that separates Mercury from the Sun. Despite its proximity to the star, the exoplanet does not receive enough energy to justify its inflated state, which has been a constant source of questions for astronomers.
Luis Welbanks, scientist at Arizona State University, explained that previously WASP-107b was believed to have an extremely small core surrounded by a huge mass of gas. However, new JWST data has led scientists to reconsider that hypothesis.
One of the keys to the mystery of WASP-107b is its extremely low density, a feature that makes it significantly different from other known gas giants. With more than three-quarters the volume of Jupiter, but less than a tenth of its mass, this planet has proven difficult to explain under traditional models of planetary formation.
A team of European astronomers has discovered deep in the spongy atmosphere of WASP-107b not only water vapor and sulfur dioxide, but even clouds of siliceous sand. Credits: Illustration: LUCA School of Arts, Belgium/ Klaas Verpoest (visuals), Johan Van Looveren (typography). Science: Achrène Dyrek (CEA and Université Paris Cité, France), Michiel Min (SRON, Netherlands), Leen Decin (KU Leuven, Belgium) / MIRI EXO GTO European Team / ESA / NASA
According to Welbanks, researchers initially assumed that WASP-107b’s small rocky core absorbed a large amount of hydrogen and helium, which would have inflated its atmosphere enormously. However, this explanation did not seem sufficient to justify its size.
“Based on its radius, mass, age, and assumed internal temperature, we think that WASP-107 b had a very small rocky core surrounded by a huge mass of hydrogen and helium. “But it was difficult to understand how such a small core could absorb so much gas and then not grow into a planet with the mass of Jupiter,” explained Welbanks, lead author of a paper published in Nature.
The JWST, with its unprecedented ability to analyze light passing through exoplanetary atmosphereshas allowed scientists to obtain a much more detailed view of WASP-107b.
Transmission spectroscopy detected a lack of methane in WASP-107b’s atmosphere, suggesting a much hotter interior.
Through the transmission spectroscopy technique, researchers have been able to measure the abundance of various molecules in the exoplanet’s atmosphere, such as water vapor, carbon dioxide, sulfur dioxide, and carbon monoxide. These data, combined with previous observations from the Hubble telescope, have revealed a surprising lack of methane (CH4) in their atmosphereindicating that its core is much more massive and its interior significantly hotter than previously thought.
According to David Sing, from Johns Hopkins University, the almost complete absence of methane in WASP-107b’s atmosphere is a clear sign that Hot gas from deep inside the planet is mixing with colder layers higher up. This phenomenon also suggests that the interior of the exoplanet is at much higher temperatures than initial estimates indicated. Since methane is unstable at high temperatures, its absence could explain why WASP-107b has maintained its swelling.
“WASP-107 b is a very interesting target for Webb because it is significantly colder and more Neptune-like in mass than many of the other low-density planets, the hot Jupiters, that we have been studying,” Sing said.
The “pochoclo or popcorn planet” presents a surprising atmospheric asymmetry between its east and west sides.
Recent studies have revealed that WASP-107b’s core is at least twice as massive as originally estimated. This has important implications for our understanding of the formation of gas giant planets.
Apparently, instead of being born with a very small nucleus and having absorbed a large amount of gas during its formation, WASP-107b might have started out with a structure more similar to that of Neptune, with a higher proportion of rock material. Subsequently, the planet’s internal warming and other factors, such as tidal heating, would have allowed its atmosphere to remain inflated.
Tidal heating, caused by WASP-107b’s elliptical orbit around its star, is one of the main explanations for why the planet is in its current state. As its distance from the star changes throughout its 5.7-day orbit, so does the gravitational pull, stretching the planet and generating an internal heat source. This process would have helped maintain the inflated state of the planet, which would otherwise have contracted over time as it cooled.
Analysis from the Webb telescope suggests that WASP-107b has a core more similar to that of Neptune, but much more inflated by its internal heat. (Credit: NASA/JPL-Caltech/R. Hurt)
Another of the Key findings provided by JWST is the identification of an asymmetry in WASP-107b’s atmosphere. Observations have revealed significant differences between the east and west sides of the planet, something that was not expected for an exoplanet like this.
According to the associate professor at Arizona State University, Michael Linethis asymmetry could be due to one side of WASP-107b being cloudier than the other, or to the way heat is transported through its atmosphere. “It’s like one side of the planet is cooking faster than the other.”Line explained.
WASP-107b is tidally locked, meaning it always has one side facing its star, in constant daylight, while the other side remains in perpetual darkness. This situation, Combined with the planet’s low gravity and inflated state, it creates an ideal environment for studying complex atmospheric processes. that take place on gas giant exoplanets.
Recent discoveries about WASP-107b have not only helped unravel the mysteries of this particular exoplanetbut have also shed light on the internal dynamics of other low-density exoplanets.
WASP-107b’s low density makes it one of the fluffiest planets known, despite its giant size. (SWRI)
The JWST data could be key to understanding why many inflated planets have characteristics similar to those of WASP-107b. As Luis Welbanks points out, “thanks to these observations, we are beginning to answer questions that we could not previously resolve with traditional observation techniques.”
As researchers continue to analyze the data obtained by JWST, they plan to conduct additional observations to better understand what drives WASP-107b’s atmospheric asymmetry and how heat is distributed within it. Ongoing studies will help astronomers reveal how inflated exoplanets maintain their structure, and how factors such as heat, winds, and atmospheric chemistry interact to create the unique conditions observed in WASP-107b.
Thanks to the advances of the James Webb telescope, WASP-107b is no longer the enigma it once was. Although its inflated state and low density remain surprising, it is now understood that its core is much more massive than previously thought, and that tidal heating and the mixing of gases in its atmosphere are key factors in explaining its unique nature. . What was once perceived as a planet with strange characteristics is now beginning to make more sense under the magnifying glass of advanced science.
The “popcorn planet” has revealed a new facet, and future studies promise to continue unraveling the secrets of the most exotic exoplanets in the universe.
