Carbon Giant by a Dead Star ✛

Original: "A carbon-rich atmosphere on a windy pulsar planet"

arXiv:2509.04558 · 2025-09-04 · CC BY 4.0 · 1 min

JWST spotted a soot planet orbiting a pulsar: its carbon-rich atmosphere turns theories upside down.

Using the James Webb Space Telescope, astronomers peered at the pulsar PSR J2322-2650b — the superdense core of an exploded star. Orbiting it is a gas giant the size of Jupiter, heated to a glow of molten steel. This pair has been dubbed the 'black widow': the dead star siphons material from its companion.

The first pulsar was discovered by Jocelyn Bell Burnell in 1967, while neutron stars were predicted by Fritz Zwicky as early as 1933.

The planet's spectrum delivered a shock: instead of water vapor, the atmosphere turned out to be soot — chains of two and three carbon atoms. Carbon is a hundred times more abundant than oxygen compared to normal, and ten thousand times more than nitrogen. Such carbon riches don't fit the 'black widow' model, where the companion should be a molten metallic core. Apparently, world-building around dead stars is far more mysterious than we thought.

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Planet PSR J2322-2650b completes a full orbit around the pulsar in 3.3 hours — faster than any human-made satellite in low Earth orbit.

Scientists

Christian Doppler D. B. McLaughlin Didier Queloz Michel Mayor R. A. Rossiter David Charbonneau

Concepts

hot jupiter atmospheres jwst exoplanet atmospheres jupiter mass exoplanet atmosphere sulfur dioxide europa super earth earth mass pulsar companion neptune pulsar wind carbon dioxide mercury hydrogen atmosphere red dwarf planets titan exoplanets around red dwarfs gas giant carbon monoxide wolf rayet star

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Carbon Giant by a Dead Star ✛