JWST just found water vapor, sulfur dioxide, and sand clouds in the atmosphere of a nearby exoplanet

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A team of European astronomers, co-led by researchers from the Institute of Astronomy, KU Leuven, has made a groundbreaking discovery using the James Webb Space Telescope (JWST).

Artist impression of WASP-107b and its parent star. Credit: 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, the Netherlands), Leen Decin (KU Leuven, Belgium) / European MIRI EXO GTO team / ESA / NASA

They have observed the atmosphere of the nearby exoplanet WASP-107b and found not only water vapor and sulfur dioxide but also silicate sand clouds. This discovery is significant as it provides insights into the dynamic and complex chemical composition of the exoplanet’s atmosphere.

Unveiling the Secrets of WASP-107b

WASP-107b is a unique gaseous exoplanet orbiting a star slightly cooler and less massive than our sun. Its mass is similar to Neptune’s, but its size is almost as large as Jupiter’s, making it unusually ‘fluffy’ compared to the gas giants in our solar system. This fluffiness allows astronomers to probe about 50 times deeper into its atmosphere than they could in a planet like Jupiter.

A Dynamic and Surprising Atmosphere

The team’s study, published in Nature, reveals the presence of water vapor, sulfur dioxide (SO2), and silicate clouds in WASP-107b’s atmosphere. Interestingly, there is no trace of methane (CH4), a greenhouse gas. The absence of methane suggests a potentially warm interior of the planet, hinting at the movement of heat energy within its atmosphere.

A transmission spectrum of the warm Neptune exoplanet WASP-107b, captured by the Low Resolution Spectrometer (LRS) of the Mid InfraRed Instrument (MIRI) on board JWST, reveals evidence for water vapour, sulfur dioxide, and silicate (sand) clouds in the planet’s atmosphere. Credit: Michiel Min / European MIRI EXO GTO team / ESA / NASA

The discovery of sulfur dioxide was unexpected, as previous models had predicted its absence. This finding indicates that the fluffiness of WASP-107b’s atmosphere allows for the formation of sulfur dioxide, despite the relatively small fraction of high-energy photons emitted by its cooler host star.

The Role of Sand Clouds

The presence of high-altitude sand clouds in WASP-107b’s atmosphere is particularly intriguing. These clouds consist of small silicate particles, similar to sand found on Earth. The study suggests that these sand clouds are formed through a continuous cycle of sublimation and condensation, driven by vertical transport within the planet’s atmosphere. This process is akin to the water vapor and cloud cycle on Earth but with droplets made of sand.

Implications for Exoplanetary Science

This research marks a significant milestone in the exploration of exoplanetary atmospheres. It not only sheds light on the exotic world of WASP-107b but also expands our understanding of the chemical and climatic conditions on distant worlds.

The JWST has enabled a deep atmospheric characterization of an exoplanet that does not have any counterpart in our solar system, opening new avenues for unraveling the mysteries of these distant worlds.

Belgian Contribution to MIRI Instrument

Belgian engineers and scientists played a crucial role in the design and development of the Mid-Infrared Instrument (MIRI) aboard the JWST, which was instrumental in this discovery. The MIRI instrument was extensively tested in special test chambers simulating the space environment in laboratories in the UK, at NASA Goddard, and NASA Johnson Space centers.
The discovery of water vapor, sulfur dioxide, and sand clouds in the atmosphere of WASP-107b by JWST’s MIRI instrument is a pivotal milestone in exoplanet research. It reshapes our understanding of planetary formation and evolution and sheds new light on our own solar system. This study represents years of work invested not only in building the MIRI instrument but also in the calibration and analysis tools for the observational data acquired with MIRI.

Reference(s): Research Paper

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