Webb finds traces of water vapor, but is it from an exoplanet or from a star?

about the episode

Astronomers studied the rocky exoplanet GJ486b using the James Webb Telescope. The planet, which is about 30 percent more massive than Earth, is too close to its star to inhabit. With surface temperatures of around 430 degrees, it’s way too hot for us.

However, near the planet, researchers discovered traces of water vapor. If this water vapor is coming from the planet, it indicates that the planet has an atmosphere, despite the enormous temperatures.

Water vapor has previously been found near gaseous exoplanets, but so far no atmosphere has been found around a rocky exoplanet. The researchers immediately add that water vapor could also come from the star, and not from the planet.

More observations are needed, along with other instruments aboard the telescope, to know for sure where the water vapor is coming from. If there really was an atmosphere, it would likely need to be continually fueled by steam from the planet’s interior.

The planet also has a fixed day side and a fixed night side. This aspect of today will be studied, among others, in a later study. How hot the warmest point is out there and where that is in relation to the star can say something about how the atmosphere circulates heat, among other things.

Read more about the discovery here: Webb finds water vapor, but from a rocky planet or its star?