[SevenNation]

Here's the part explaining the active chemistry:

> The team were also surprised to detect sulfur dioxide, which had appeared as a mysterious bump in early observation data. Its presence suggests a photochemical reaction is taking place in the atmosphere as light from the star hits it, similar to how our Sun produces ozone in Earth’s atmosphere. In WASP-39b’s case, light from its star, slightly smaller than the Sun, splits water in its atmosphere into hydrogen and hydroxide, which reacts with hydrogen sulfide to produce sulfur dioxide.

Wikipedia has this to say about sulfur dioxide in our solar system:

> On other planets, sulfur dioxide can be found in various concentrations, the most significant being the atmosphere of Venus, where it is the third-most abundant atmospheric gas at 150 ppm. There, it reacts with water to form clouds of sulfuric acid, and is a key component of the planet's global atmospheric sulfur cycle and contributes to global warming.[11] It has been implicated as a key agent in the warming of early Mars, with estimates of concentrations in the lower atmosphere as high as 100 ppm,[12] though it only exists in trace amounts. On both Venus and Mars, as on Earth, its primary source is thought to be volcanic. The atmosphere of Io, a natural satellite of Jupiter, is 90% sulfur dioxide[13] and trace amounts are thought to also exist in the atmosphere of Jupiter.

https://en.wikipedia.org/wiki/Sulfur_dioxide

This doesn't necessarily mean that the the exoplanet has active volcanism, but it could be an explanation.

[6177c40f]

Isn't WASP-39b a gas giant? Is it even possible for such a planet to have active volcanism?