This Hot Saturn’s Atmosphere Lacks Any Trace of Clouds

Researchers have discovered that a distant planet from the “hot Saturn” class of gas giant exoplanets is completely cloudless. The discovery could mark a turning point in exoplanet research.

University of Exeter’s Nikolay Nikolov and his team used the Chile-based 8.2m Very Large Telescope to make the discovery. The imagery revealed that WASP-96b, a large planet beyond our solar system, is cloud-free.

Astronomers analyzed the planet’s features when it crossed above the surface of its host star. The team measured the variation in the alien star’s light caused by the transiting hot Saturn to better understand the planet’s atmosphere.

The team explained that molecules and atoms have a unique blueprint which researchers can look for to detect their presence in distant celestial bodies. An analysis of WASP-96b’s atmosphere revealed high levels of sodium, which can only appear in an environment with no clouds.

A research paper about the discovery appeared Monday (May 7) in the journal Nature.

A Hot Saturn with a Cloud-Free Atmosphere

The hot gas giant is dubbed a “hot Saturn” because it is similar in size with our solar system’s Saturn. The planet periodically transitions its host star in the direction of the constellation Phoenix.

Past studies had predicted that sodium must be present in large quantities in the atmospheres of hot gas giants from alien solar systems. Cloud-free atmospheres produce unique transit spectra that can be easily spotted by researchers.

Lead author Nikolov explained that the team analyzed over 20 transit spectra from as many exoplanets, but WASP-96b is the only exoplanet that lacks clouds. Nikolov described the hot Saturn as a benchmark for characterization in exoplanet research due to its clear sodium signature and features.
Image Source: Wikimedia