Using the James Webb Space Telescope (JWST), researchers from the National Aeronautics and Space Administration (NASA) discovered an unprecedented "weird planet" - PSR J2322-2650b. It not only orbits a pulsar, but also has an almost "pure carbon" atmosphere and a material structure that may be crystallizing into diamonds internally. It is described as "a completely unexpected planet type."
The James Webb Telescope is currently the most powerful infrared space telescope in the world. It was jointly developed by NASA, the European Space Agency and the Canadian Space Agency. It mainly studies cooler planets, diffuse dusty areas and extremely distant galaxies by observing the infrared band. These targets are often difficult to be directly seen by ordinary optical telescopes. In this observation, the Webb Telescope locked onto an exoplanet named PSR J2322-2650b, which is roughly the same mass as Jupiter but orbits a pulsar, which is extremely rare in known planetary systems.
The so-called pulsar is a type of rapidly rotating neutron star. It is the dense core left after the supernova explosion of a massive star. It can be larger than the sun in mass, but only the size of a city. Pulsars emit beams of electromagnetic radiation along the direction of their magnetic poles. As they rotate, these radiation beams sweep across the sky like a lighthouse, thus showing periodic pulse signals in observations. Currently, only a handful of planets known to the astronomical community have been discovered orbiting pulsars, and PSR J2322-2650b is completely different in composition and structure from similar targets previously recorded.
Observation results show that the planet's atmosphere is mainly composed of helium and carbon, rather than water, methane and other molecules common in most exoplanets. The scientific research team detected molecular carbon in its atmospheric spectrum, especially C₂ and C₃. This type of molecules composed of carbon atoms directly bonded is extremely rare in planetary atmospheres, because usually, carbon prefers to combine with oxygen or hydrogen to form compounds such as carbon dioxide or methane. Researchers pointed out that the planet's atmospheric carbon-to-oxygen ratio exceeds 100, and the carbon-to-nitrogen ratio is even higher than 10,000, far exceeding most known exoplanets, which means that its atmosphere can almost be regarded as a "highly carbon-rich environment."
Peter Gao, a scientist at the Carnegie Earth and Planetary Laboratory who participated in the study, said that when the team saw the data for the first time, they "could hardly believe their eyes" and lamented that "this is not the kind of planetary atmosphere we expected at all." Michael Zhang of the University of Chicago pointed out that the pulsar that the planet orbits is extremely special in itself - "close to the mass of the sun but only the size of a city", and the type of atmosphere of PSR J2322-2650b "is a new category that has never been seen before."
Under extreme conditions of temperature and pressure, the planet takes on an even more bizarre aspect. Research shows that there is a huge temperature difference between day and night: the temperature on the night side is about 1,200 degrees Fahrenheit (about 650 degrees Celsius), and the temperature on the day side is as high as about 3,700 degrees Fahrenheit (about 2,000 degrees Celsius). In such an environment, there are soot-like carbon dust clouds floating in the atmosphere. Researchers speculate that under the huge pressure inside the planet, these carbon dust clouds may gradually transform into crystal structures such as diamonds, and the crystallization process of carbon may be occurring deep in the planet.
Roger Romani of Stanford University explained that as the companion star cools, the carbon-oxygen mixture inside it begins to crystallize, and pure carbon crystals "float" to the upper layers and mix with helium, which is the source of the atmospheric features seen in observations. He also pointed out that it is still a huge mystery to explain why oxygen and nitrogen are excluded from this process. "There must be some key mechanism to 'block aside' them. This is a problem that has not yet been solved."
From the perspective of track structure, this system also carries an "extreme label". PSR J2322-2650b is only about 1 million miles away from its pulsar. By comparison, the average distance between the Earth and the sun is about 100 million miles, which is a hundred times that distance. In such a tight orbit, the planet only takes about 7.8 hours to complete one revolution (its year), which is far shorter than an Earth year.
Strong gravitational tidal effects cause the planet to be "pulled" into a lemon-like shape rather than an approximate sphere. Gravity is the basic force that causes objects with mass to attract each other. When a dense celestial body is very close to its companion star and has a huge disparity in mass, the tidal force will produce a significant stress difference inside the companion star, leading to overall deformation. This phenomenon is particularly obvious in PSR J2322-2650b.
The scientific research team believes that this system may be somehow related to the so-called "black widow" system in astronomy. "Black Widow" systems are usually composed of a pulsar and a close companion star. The pulsar continuously "cannibalizes" the companion star material through intense radiation and high-energy particle flow, and eventually only a highly dense remnant core may be left. However, in this discovery, PSR J2322-2650b has a mass lower than 13 Jupiter masses, so it is officially classified as an exoplanet, not a "companion" in the sense of a stellar debris.
In terms of its formation mechanism, it is also difficult to apply existing theoretical models to this planet. Zhang pointed out that judging from the currently observed composition, this celestial body is obviously not formed by gradually aggregating in the protoplanetary disk gas and dust around a young star like an "ordinary planet", because its atmospheric chemical composition is completely different from that of ordinary planets. At the same time, there are problems in treating it as the remnant core of a star that has been denuded in the "Black Widow" system, because the existing nuclear physics processes do not support the formation of almost "pure carbon" objects, which means that our understanding of its origin is still very preliminary.
This discovery was made possible thanks to the Webb Telescope's keen vision in the infrared band. Infrared light can penetrate dust clouds in the universe and help astronomers observe cooler and darker targets. The pulsar itself mainly emits gamma rays and high-energy particles. These radiations are outside Webb's working band and therefore will not interfere with infrared spectroscopic measurements of planetary atmospheres.
By analyzing a planet's spectral fingerprint at different wavelengths, scientists can infer which atoms and molecules are present in its atmosphere and further estimate key parameters such as temperature, chemical composition and pressure structure. Maya Beleznay of Stanford University pointed out that in this system, researchers can "only see the spectrum of the planet illuminated by the pulsar, and almost never directly see the pulsar itself." This provides rare conditions for obtaining clean and clear spectral signals, giving this system unique advantages in exoplanet research.
The total number of confirmed exoplanets is about 6,000. Among this large sample, PSR J2322-2650b is the only target that forms such a peculiar combination between the orbital characteristics of a "hot Jupiter" and the properties of a "pulsar companion". Its unusual carbon-rich atmosphere, extreme chemical composition, lemon-shaped shape stretched by gravity, and unusually compact dynamic structure together constitute an unprecedented planetary sample, which raises new questions about how planets form, evolve and even survive in extreme cosmic environments. It also opens up new observation directions for future planetary science and high-energy astrophysics research.