JWST and VLT reveal super-solar metallicity and photochemical signs in WASP-96b's atmosphere

Star system: WASP 96 | Distance from the Sun: 1141 light years

WASP-96b is a hot Saturn-like planet whose atmosphere has been studied using both the James Webb Space Telescope and ground-based telescopes. The combined data show clear signs of water vapor, carbon dioxide, and sodium in the planet's atmosphere. While carbon monoxide could not be confirmed, the results suggest that the atmosphere contains two to six times more heavy elements than its star, a property known as super-solar metallicity.

The planet's carbon-to-oxygen ratio is similar to that of its star, which hints that WASP-96b may have formed far from its star and later collected material rich in volatile elements. The analysis also found a moderate preference for the presence of sulfur dioxide, a molecule that can be produced by photochemical reactions driven by the star's light. The spectrum shows a slope in the optical range, which could be caused by small particles in the atmosphere, such as clouds or hazes, or possibly by sodium or effects from the star itself.

These findings highlight the complexity of exoplanet atmospheres and the need for further observations to better understand the roles of photochemistry, clouds, and possible differences between the planet's limbs.

Key findings
- WASP-96b's atmosphere has super-solar metallicity (2–6 times stellar)
- Water vapor, carbon dioxide, and sodium detected
- Possible presence of sulfur dioxide from photochemistry
- Optical slope may be due to clouds, hazes, or sodium
- More data needed to confirm limb asymmetry and disentangle atmospheric effects

Scientific study

Super-Solar Metallicity and Tentative Evidence for Photochemistry on WASP-96b from JWST and Ground-Based VLT Transmission Spectroscopy (external link)