Webb Telescope Reveals ‘Lemon’ Planet Made of Helium and Carbon, Challenging Planetary Formation
A newly observed exoplanet, PSR J2322-2650b, is unlike anything astronomers have encountered, boasting a severely distorted shape and an atmosphere devoid of common planetary elements. The findings, published Tuesday in The Astrophysical Journal Letters, raise questions about its very nature – is it a planet, or the remnant of a star being consumed?
Our own Earth isn’t perfectly spherical, bulging slightly at the equator due to its rotation. But this distortion pales in comparison to PSR J2322-2650b, a gas giant comparable in mass to Jupiter, located over 2,000 light years away. Observations from the James Webb Space Telescope reveal that this distant world’s equatorial diameter is a staggering 38 percent wider than its polar diameter, giving it a distinctly lemon-like appearance.
Discovered in 2011 by Australia’s Parkes radio telescope, PSR J2322-2650b immediately intrigued scientists as the only known gas giant orbiting a pulsar – a rapidly spinning, incredibly dense star formed from a supernova. The planet whips around its star in a mere eight hours, at a distance of just one million kilometers. This extreme proximity, according to one exoplanet scientist, is the key to its bizarre form. “It’s close enough that everything is funneled from the object to the pulsar,” they explained. “You have a literal tip, like a point, where material leaves the planet and spirals in.”
The Webb telescope’s infrared capabilities allowed researchers to analyze the planet’s atmosphere for the first time. The results were astonishing. Unlike other gas giants, PSR J2322-2650b lacks hydrogen, oxygen, and nitrogen. Instead, its atmosphere is dominated by helium and molecular carbon. “A world dominated by helium and carbon is something we have never seen before,” stated another researcher involved in the study.
This unusual composition suggests even more extraordinary possibilities. The planet’s carbon-rich atmosphere could produce clouds of graphite and, potentially, a core of diamonds. Bands of storms would likely trace the planet’s W-shaped exterior, giving it a reddish hue from dust and soot-like carbon particles. “It’s a weird, bizarre thing,” remarked a theoretical astrophysicist at the University of Michigan, who was not involved in the research. “It hasn’t formed like any other normal planet.”
However, the planet’s strange properties have led scientists to consider a more radical hypothesis: that PSR J2322-2650b isn’t a planet at all, but the remains of a star slowly being devoured by the pulsar. This scenario would classify the system as a black widow pulsar, where a star is systematically stripped of its mass. “We’re leaning toward the star hypothesis,” said an exoplanet scientist at the Carnegie Institution for Science. “It would have lost 99.9 percent of its mass, and we have detected it right at the end.”
Alternatively, the object could represent a completely new class of celestial body, one that doesn’t fit neatly into existing astronomical categories. In this case, PSR J2322-2650b could remain in a stable orbit around its pulsar for billions of years. Researchers are eager to find similar objects to compare with PSR J2322-2650b. “I hope we have a brother to compare this object to,” one scientist said. “If it is continually losing mass, we have had to be very lucky to see it in its last breath before disappearing.”
The discovery underscores the vastness of the universe and the potential for worlds beyond our imagination, challenging our fundamental understanding of planetary formation and the very definition of a planet.
