Astronomy: The atmosphere of a white dwarf planet (Nature)
2 July 2026
JWST observations of a planet orbiting a white dwarf reveal details of the planet’s atmosphere, which may offer insights into the fate of our own Solar System when the Sun dies. The findings are published in Nature.
Most stars, including our Sun, will eventually die leaving behind a white dwarf. How this stellar evolution process might affect the planets orbiting these stars is not fully understood. Some planet candidates have been found orbiting white dwarfs, indicating that planets can survive the phase where stars evolve into red giants before becoming a white dwarf. However, little is known about the atmospheric composition of such planets.
Ryan MacDonald and colleagues report the detection of an atmosphere of WD 1856 b, a planet orbiting a white dwarf in a roughly 10-billion-year-old system located 25 parsecs from Earth, as measured by a spectrograph on the JWST. They find that the atmosphere is rich in methane and aerosols. The mass of WD 1856 b is estimated to be around 4.3–10.9 times the mass of Jupiter (MJ). The atmosphere was reheated in its migration to its currently close orbit of just 0.02 astronomical unit (approximately 3,000,000 km from its star). The authors also calculate the temperature of the planet’s atmosphere to be around 390–412 K, which exceeds temperatures expected for giant planets (160 K). This finding indicates that planetary reheating took place billions of years after the end of the red giant phase.
WD 1856 b represents the first well-characterized transiting planet orbiting a white dwarf, the authors propose. The observations of this planet’s migration, and evolution of the composition and temperature of its atmosphere, may help scientists to determine the fate of planetary systems after the death of their star.
- Article
- Open access
- Published: 01 July 2026
MacDonald, R.J., O’Connor, C.E., Boehm, V.A. et al. Aerosols and hydrocarbons in the atmosphere of a white dwarf planet. Nature 655, 76–80 (2026). https://doi.org/10.1038/s41586-026-10514-7
© 2026 Springer Nature Limited. All Rights Reserved.
