NEW YORK. – The Earth is not a perfect sphere. Due to the rotation of our planet, it bulges slightly at the equator and is 0.3 percent wider there than from pole to pole.
But that’s nothing compared to this PSR J2322-2650ban object with a Mass comparable to that of Jupiter recently studied by the James Webb Space Telescope. This planet’s equatorial diameter is 38 percent larger than its polar diameter, giving it the strange appearance of a lemon and a very strange atmosphere.
“It is the most elastic planet that we have confirmed to be expanding,” he said. Michael Zhangan exoplanet scientist at the University of Chicago and lead author of a paper about the planet published Tuesday in The Astrophysical Journal Letters.
PSR J2322-2650b was discovered by Australia’s Parkes radio telescope in 2011. It lies more than 2,000 light-years from Earth. As a Jupiter-sized gas giant orbiting a pulsar, a dense, rapidly spinning star formed from a supernova, it was immediately interesting. Pulsars are so named because they emit beams of radiation from their poles. The planet is only a million kilometers from the star and takes about eight hours to complete one orbit. It is the only known gas giant orbiting a pulsar.
This proximity gives the planet its unusual shape as the star’s gravity pulls on it. “It’s close enough that everything is directed from the object to the pulsar,” said Peter Gao, an exoplanet scientist at the Carnegie Institution for Science in Washington and author of the paper. “They have a literal tip, like a point where material leaves the planet and spirals in.”
Using the Webb Telescope’s infrared capabilities, the team was able to study the planet’s atmosphere. This was the first time this had been done for a planet orbiting a pulsar. Such observations indicated the strange shape of the world. And they also revealed something extremely strange: the planet lacks hydrogen, oxygen and nitrogen, elements found on other planets, including gas giants. Instead, it consists mostly of helium and molecular carbon. “We have never seen a world dominated by helium and carbon before,” Gao said.
Its carbon atmosphere could give it “clouds of graphite” and diamonds at its core, Zhang said. Storm bands would paint the world’s lemon-like, W-shaped exterior, while it would most likely be red in color due to dust and soot-like particles formed by carbon.
“It’s a strange, bizarre thing,” said Emily Rauscher, a theoretical astrophysicist at the University of Michigan who was not involved in the work. “It didn’t form like any other normal planet.”
The strange properties of PSR J2322-2650b could mean that it is not actually a planet, but rather the remnant of a star that orbited the pulsar and was slowly swallowed up. “We’re leaning toward the stellar hypothesis,” Gao said, which could make it a type of system known as a Black Widow pulsar, in which we see a star being engulfed by a pulsar.
It could be the final moments of such a system, as PSR J2322-2650b is on the verge of complete exhaustion. “It would have lost 99.9 percent of its mass, and we only discovered it at the end,” Gao said.
Alternatively, Zhang said, it could be “an entirely new type of object that we don’t have a name for,” with PSR J2322-2650b remaining in a stable orbit around its pulsar for billions of years rather than being immediately devoured. He hopes to search for more such worlds in the future to find out.
“I hope we have a brother to compare this object to,” he said. “If it continues to lose mass, we had to be very lucky to see it in its final breath before it disappeared.”
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