Overview
- A University of St Andrews–led team published a Nature paper on July 1, 2026, reporting Webb transmission spectroscopy of WD 1856 b that revealed the first confirmed atmosphere on a planet transiting a white dwarf.
- The JWST grazing‑transit data show cloud particles and hydrocarbons, most likely methane, and place the planet’s temperature at about 400 K (≈126°C), far hotter than white‑dwarf irradiation alone would allow.
- Analysis of the transit spectrum also constrains WD 1856 b’s mass to roughly 4–11 times Jupiter’s mass and confirms its extremely tight orbit around the Earth‑sized white dwarf about 80 light‑years away.
- Cooling and orbital models reconstructed from the measured mass and temperature indicate extra heating began roughly 3–5.5 billion years after the star became a white dwarf, a timing that favors inward migration long after stellar death over immediate post‑engulfment survival.
- Researchers have collected additional JWST transits to refine the atmospheric chemistry and test the migration and heating scenarios, and the result expands how astronomers think gas giants can survive and change after a star’s death.