An international team of astronomers has used the James Webb Space Telescope (JWST) to observe the exoplanet WD 1856 b as it transited its host star, a white dwarf. They have successfully measured the planet's mass and temperature, and for the first time, detected its atmosphere. This finding provides the first direct insight into the fate of gas giant planets, similar to Jupiter, after their host star exhausts its nuclear fuel and becomes a white dwarf, a scenario awaiting our own solar system billions of years from now.

The researchers found that WD 1856 b is significantly warmer than anticipated. In addition to the atmospheric detection, the study has allowed for the determination of the most probable mechanism by which the planet reached its current, extremely close orbit around the white dwarf. This discovery is crucial for understanding planetary dynamics in post-main-sequence stellar systems and offers clues about the potential habitability of such worlds in the distant future of the universe.