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JWST spots 260°F gas giant orbiting dead star.

7/3/2026

Summary

Astronomers Observe WD1856b

Astronomers led by Dr. Christopher O’Connor used the James Webb Space Telescope to observe WD 1856 b, a gas giant that orbits its dwarf star every 34 hours.
The planet, discovered in 2020 by NASA’s TESS and Spitzer, shows methane, particles and a temperature of about 260 °F (127 °C), implying internal heating.
Researchers estimate its mass at four-to-11 Jupiter masses and argue it migrated inward after the star died, from gravitational interactions with outer stars.

Summary

JWST Images Planet

JWST images of WD 1856 b show a planet orbiting a white dwarf, confirming a system after a Sun-like star dies.
At 80 light-years, WD 1856 b is among the nearest white-dwarf planets.
The Sun will engulf inner rocky planets, including Earth, when it becomes a red giant, while outer giants may survive altered.
The finding implies future surveys may uncover more post-mortem systems, improving predictions of long-term habitability and the solar system’s fate.

Summary

JWST Tracks Planet

JWST captured transits of planet WD 1856 b across white dwarf WD 1856+534 to measure its mass, temperature and atmosphere.
Its temperature exceeds predictions for a gas giant so close to a cooling white dwarf.
Researchers propose a post-red-giant migration that moved the Jupiter-size world into a 34-hour orbit.
The team led by Ryan MacDonald, University of St Andrews team leader, will launch a systematic JWST search for additional white-dwarf planets using transit-spectroscopy.

Summary

JWST Detects Methane

JWST required custom atmospheric models because WD 1856b’s grazing transit only partially covers its faint white dwarf.
The transit dims the star by a record 56 % and lasts only eight minutes.
Researchers treated the atmosphere as a thin annulus rather than a full disc, enabling detection of methane and tiny cloud particles.
Four additional JWST transits are scheduled to refine the new analysis methods.

History

Historical Context

In 1992 Aleksander Wolszczan and Dale Frail confirmed three Earth-mass planets around the millisecond pulsar PSR B1257+12 using the Arecibo Observatory, the first extrasolar worlds discovered. Their rarity—only about half a dozen pulsar planets known, roughly one per 200 pulsars—prompted continued searches for planets that survive stellar death, and inform modern habitability models.

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Astronomers Observe WD1856b

Astronomers led by Dr. Christopher O’Connor used the James Webb Space Telescope to observe WD 1856 b, a gas giant that orbits its dwarf star every 34 hours.
The planet, discovered in 2020 by NASA’s TESS and Spitzer, shows methane, particles and a temperature of about 260 °F (127 °C), implying internal heating.
Researchers estimate its mass at four-to-11 Jupiter masses and argue it migrated inward after the star died, from gravitational interactions with outer stars.

1 / 5