James Webb Probes WD 1856 b, Finding Jupiter-Size Planet Skims White Dwarf at 0.02 AU
Updated
Updated · Ars Technica · Jul 10
James Webb Probes WD 1856 b, Finding Jupiter-Size Planet Skims White Dwarf at 0.02 AU
3 articles · Updated · Ars Technica · Jul 10
Summary
WD 1856 b’s transits dim its white dwarf host by only about 50%, leading astronomers to conclude the Jupiter-size planet likely clips only the star’s edge in a rare grazing orbit.
James Webb provided the first close look at the system, sharpening a puzzle first spotted in 2020 when TESS surveyed roughly 2,000 white dwarfs and unexpectedly found a gas giant.
At just 0.02 AU, the planet sits far closer to the white dwarf than standard models predict after a Sun-like star swells into a red giant, engulfs inner planets and then loses about half its mass.
The system remains the only confirmed case of a planet surviving the death of a Sun-like star, making WD 1856 b a key test for theories of planetary migration after stellar collapse.
Could this 'zombie' planet orbiting a dead star reveal the ultimate fate of Jupiter and Saturn in our own solar system?
How does a giant planet survive its star's fiery death, only to spiral into an impossibly close orbit billions of years later?
JWST Reveals Methane-Rich Atmosphere on WD 1856 b, a Jupiter-Sized Exoplanet Orbiting a White Dwarf
Overview
The James Webb Space Telescope (JWST) made a historic breakthrough by detecting an atmosphere around the exoplanet WD 1856 b, which orbits a white dwarf star. Using JWST's NIRSpec PRISM instrument, astronomers captured the planet's brief transit and revealed a complex atmosphere rich in methane, carbon compounds, and aerosols. Surprisingly, the atmosphere is much warmer than expected, with temperatures between 117–139°C. This discovery marks a pivotal step in understanding how planetary systems can survive and evolve after their host stars become white dwarfs, offering new insights into the resilience and transformation of planets in extreme environments.