Overview
- A team led by the University of St Andrews published a Nature paper on July 1, 2026 reporting the first detailed transmission spectrum of a planet around a white dwarf, obtained with the James Webb Space Telescope.
- Webb detected a clear atmosphere on WD 1856b with small cloud particles and hydrocarbons such as methane, and the system’s grazing eight‑minute transit forced the development of new analysis models.
- Infrared data indicate WD 1856b is much hotter than expected at roughly 400 kelvin (about 126°C) and the transit analysis implies a large mass of about four to eleven times Jupiter’s mass.
- Cooling and tidal‑heating models reconstructed from the planet’s mass and temperature place a reheating event about 3 to 5.5 billion years after the host became a white dwarf, supporting a late inward migration scenario while leaving two migration hypotheses viable.
- Researchers have already taken additional JWST transits to improve atmospheric and dynamical constraints, and the result expands how scientists think gas giants like Jupiter could survive and change after their star dies.