Massive surprise from NASA’s Webb telescope: a Jupiter-mass exoplanet with a atmosphere shaped by chemistry nobody expected.
But here’s where it gets controversial: this world, officially named PSR J2322-2650b, orbits a pulsar and appears to be dominated by helium and carbon in its atmosphere. Webb’s infrared eyes detect soot-like clouds and carbon particles that could even crystallize into diamonds deep inside the planet. The origin of such an atmosphere remains a mystery, and the team plans to publish their findings in The Astrophysical Journal Letters.
The planet orbits a pulsar, a rapidly spinning neutron star that beams regular pulses toward Earth. These pulses, typically gamma rays and other high-energy particles, don’t affect Webb’s infrared observations, allowing scientists to study the planet across its entire orbit without the glare of a visible host star.
As one researcher, Maya Beleznay of Stanford, explains, the system is unusual because we can see the planet illuminated while the host star itself stays invisible. This setup yields a unusually clean spectrum, enabling a more detailed study than is possible for most exoplanets.
Michael Zhang of the University of Chicago, the study’s principal investigator, highlights the novelty: the star is Sun-like in mass but tiny in size, and the planet’s atmosphere lacks the familiar molecules like water, methane, and carbon dioxide. Instead, the observations reveal molecular carbon, including C3 and C2, a configuration that is unprecedented at the observed temperatures. At these temperatures, carbon typically bonds with other elements, so a carbon-dominant atmosphere implies extremely low levels of oxygen or nitrogen.
PSR J2322-2650b sits extraordinarily close to its star—about 1 million miles away, versus Earth’s 93 million miles from the Sun. Its orbital period is a mere 7.8 hours, and the intense gravity from the massive pulsar distorts the planet into a lemon-like shape.
The system resembles a “black widow” setup, where a fast-spinning pulsar gradually erodes a smaller companion. However, this companion is an exoplanet, not a star, and the International Astronomical Union defines exoplanets as bodies below 13 Jupiter masses that orbit a star, brown dwarf, or stellar remnant such as a pulsar.
Among roughly 6,000 known exoplanets, this is the only hot-Jupiter–like planet found in such a pulsar system with this kind of carbon-rich atmosphere. Only a handful of pulsars are known to host planets.
Zhang notes the core mystery: did this world form in a conventional planetary manner, or did an unusual process strip material from a star in a way that produced pure carbon? The observed abundance of carbon makes many standard formation scenarios unlikely.
Co-author Roger Romani from Stanford and the Kavli Institute offers a vivid possibility: as the planet cools, interior carbon and oxygen might crystallize, causing pure carbon crystals to rise and mix into the helium-rich outer layers. Yet keeping oxygen and nitrogen out—and sustaining this extreme carbon enrichment—remains an open puzzle.
Romani adds a note of scientific excitement: it’s valuable to have a puzzling atmosphere to chase, and he looks forward to more data to unravel its odd chemistry.
An accompanying animation portrays an exotic planet orbiting a distant pulsar, stretched by tidal forces into a lemon shape at a distance of about one million miles.
Webb’s success here underscores the telescope’s unique capabilities. Positioned far from Earth with a large sunshield to keep instruments unusually cold, Webb can observe infrared signatures that ground-based telescopes cannot. Webb is an international collaboration led by NASA with partners ESA and CSA.
For more about Webb, visit: https://science.nasa.gov/webb
This article provides downloadable images and videos in multiple resolutions, along with related information, media contacts, and links to the research paper and a Spanish translation where available.
