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JWST Detects Hydrocarbons, 7% Methane on WD 1856b

7/7/2026

Summary

JWST Finds Hydrocarbons

U.S. astronomers using the James Webb Space Telescope detected hydrocarbons, aerosols and about 7 % methane in exoplanet WD 1856 b’s atmosphere on 27 April 2023.
Nightside thermal emission shows an atmospheric temperature of 390–412 K, hotter than heating from the white dwarf alone.
Models suggest the planet migrated inward 3–5.5 billion years after the star became a white dwarf, likely due to the dwarf’s gravity or triple-star interactions.

Summary

WD 1856 b Case Study

Authors say WD 1856 b is a case study, not a direct forecast for the Sun’s future.
The Sun will become a white dwarf in five billion years, likely swallowing Mercury, Venus and Earth.
Cooling-model places heating 3–5.5 billion years after the star became a white dwarf, favoring late migration.
Boehm’s team secured four extra James Webb transits to refine WD 1856 b’s atmosphere.
Methane-like signatures rely on a single two-hour transit and remain provisional.

History

Historical Context

In 1995 Michel Mayor and Didier Queloz announced 51 Pegasi b, the first hot-Jupiter around a Sun-like star, revealing a 4.2-day orbit and prompting migration theories. Decades later, the James Webb Space Telescope’s 2023 spectroscopy of the white-dwarf planet WD 1856 b detected methane and a 390–412 K atmosphere, extending planetary survival studies beyond the main sequence and building on earlier white-dwarf detections such as WD 0806-661 B (2011).

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JWST Finds Hydrocarbons

U.S. astronomers using the James Webb Space Telescope detected hydrocarbons, aerosols and about 7 % methane in exoplanet WD 1856 b’s atmosphere on 27 April 2023.
Nightside thermal emission shows an atmospheric temperature of 390–412 K, hotter than heating from the white dwarf alone.
Models suggest the planet migrated inward 3–5.5 billion years after the star became a white dwarf, likely due to the dwarf’s gravity or triple-star interactions.

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