James Webb Telescope Discovers Water Vapor, Sulfur Dioxide, and Sand Clouds on Nearby Exoplanet

A team of European astronomers, including researchers from KU Leuven’s Institute of Astronomy, utilized the James Webb Space Telescope for recent observations on the atmosphere of the nearby exoplanet WASP-107b. Peering deep into its cloudy atmosphere, they identified water vapor, sulfur dioxide, and even silicate sand clouds. These elements exist within a dynamic atmosphere that shows active material transport.

Scientists globally are utilizing JWST’s Mid-Infrared Instrument (MIRI) for groundbreaking studies of exoplanets, such as WASP-107b. This unique gas planet orbits a slightly cooler, less massive star than our Sun, possessing a mass similar to Neptune but a much larger size, nearing that of Jupiter. This makes WASP-107b notably ‘fluffy’ compared to gas giants in our solar system, allowing astronomers to explore its atmosphere roughly 50 times deeper than that of Jupiter.

Leveraging the exoplanet’s fluffiness, European astronomers delved deeply into its atmosphere, unraveling its intricate chemical composition. The lower density of its atmosphere enhances the visibility of signals or spectral features compared to denser atmospheres. Their recent Nature publication highlights the presence of water vapor, sulfur dioxide (SO₂), and silicate clouds, notably lacking methane (CH₄), a greenhouse gas.

A dynamic atmosphere

These findings offer crucial insights into the behavior and chemical makeup of this intriguing exoplanet. Firstly, the lack of methane suggests a potentially warm interior, providing an intriguing glimpse into how heat energy circulates within the planet’s atmosphere.

Secondly, the detection of sulfur dioxide, typically associated with the smell of burnt matches, was an unexpected revelation. Earlier models had predicted its absence, yet newly developed climate models of WASP-107b’s atmosphere indicate that the exoplanet’s unique fluffiness supports the presence of sulfur dioxide.

Despite its cooler host star emitting a relatively small amount of high-energy photons, the exoplanet’s airy nature allows these photons to penetrate deeply, enabling the necessary chemical reactions for sulfur dioxide formation.

However, the observations don’t stop there. Both the spectral characteristics of sulfur dioxide and water vapor are notably reduced compared to what they would be in a scenario without clouds. Upper-atmosphere clouds partially mask the presence of water vapor and sulfur dioxide.

While clouds have been suggested on other exoplanets, this marks the first instance where astronomers have definitively identified the chemical composition of these clouds. In this case, the clouds comprise tiny silicate particles, a familiar substance on Earth, primarily found as the main constituent of sand in various parts of the world.

“JWST is transforming how we study exoplanets, offering unparalleled insights with exceptional speed,” stated Prof. Leen Decin of KU Leuven, the lead author. “The identification of sand, water, and sulfur dioxide clouds on this ‘fluffy’ exoplanet by JWST’s MIRI instrument is a pivotal breakthrough. It reshapes our comprehension of planetary origins and development, casting new illumination on our Solar System.”

Webb spots exoplanet elements: Earth’s atmosphere

Unlike Earth’s atmosphere, where low temperatures cause water to freeze, in gaseous planets with temperatures soaring around 1000 degrees Celsius, silicate particles can solidify, forming clouds.

However, in the case of WASP-107b, with an outer atmosphere temperature around 500 degrees Celsius, conventional models predicted these silicate clouds to form deeper, where temperatures are much higher. Additionally, sand clouds at high altitudes precipitate. How, then, do these sand clouds persist at such heights?

According to Dr. Michiel Min, the lead author, “The presence of these sand clouds high in the atmosphere implies that the sand raindrops vaporize in deeper, extremely hot layers, and the resulting silicate vapor efficiently ascends, where it recondenses to form silicate clouds again. This parallels Earth’s water vapor and cloud cycle but with droplets composed of sand.” This continuous process of evaporation and condensation via vertical transport maintains the enduring existence of sand clouds in WASP-107b’s atmosphere.

This groundbreaking study not only illuminates the exotic environment of WASP-107b but also pushes the boundaries of our comprehension of exoplanetary atmospheres. It signifies a significant leap in exploring exoplanets, uncovering the intricate interplay of elements and climatic conditions on these distant worlds.

“JWST allows for a comprehensive study of the atmosphere of an exoplanet that has no equivalent in our Solar System. We are uncovering new worlds!” expressed Dr. Achrène Dyrek, the lead author at CEA Paris.

Webb spots exoplanet elements: Design and development of the MIRI instrument

Thanks to funding provided by the Belgian federal science policy office BELSPO through the ESA PRODEX program, Belgian engineers and scientists have played a pivotal role in designing and developing the MIRI instrument. This involvement included contributions from the Centre Spatial de Liege (CSL), Thales Alenia Space in Charleroi, and OIP Sensor Systems in Oudenaarde.

At KU Leuven’s Institute of Astronomy, instrument scientists extensively tested the MIRI instrument in specialized chambers, simulating the space environment, within laboratories in the UK, NASA Goddard, and NASA Johnson Space Centers.

“With collaborators across Europe and the United States, we’ve been involved in constructing and testing the MIRI instrument for nearly two decades. Witnessing our instrument unveil the atmosphere of this fascinating exoplanet is truly gratifying,” remarked instrument specialist Dr. Bart Vandenbussche from KU Leuven.

“This research consolidates findings from numerous independent analyses of JWST observations and represents the culmination of years of effort not just in building the MIRI instrument but also in calibrating and analyzing the observational data obtained through MIRI,” added Dr. Jeroen Bouwman from the Max-Planck-Institut für Astronomie in Germany.

Read the original article on sciencedaily.

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