NASA's James Webb Space Telescope (JWST) has discovered a rare exoplanet, whose extraordinary composition has stunned scientists as it defies all possible explanations that we have so far. This Jupiter-sized planet, named PSR J2322-2650b, is outside our solar system and orbits a pulsar, a rapidly spinning neutron star, at a distance of just 1 million miles, making its year a mere 7.8 hours.
According to a paper published on Tuesday in The Astrophysical Journal Letters, the planet's atmosphere is dominated by helium and molecular carbon (C3 and C2), with clouds of soot and possible diamond formation deep within.
This composition is unprecedented among the 150 planets studied in detail, with no oxygen or nitrogen present.
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"This was an absolute surprise," study co-author Peter Gao of the Carnegie Earth and Planets Laboratory in Washington said as quoted in NASA's report.
"I remember after we got the data down, our collective reaction was 'What the heck is this?' It's extremely different from what we expected."
The distant planet appears to be in the shape of a lemon as the pulsar's intense gravity stretches the planet. It is just 1 million miles away from the pulsar. To give a perspective, Earth's distance from the Sun is about 100 million miles. This extremely tight orbit results in this bizarre shape.
As per NASA's blog, the surface temperatures range from 1,200 degrees F to 3,700 degrees F.
The molecular carbon dominates the atmosphere, unlike typical exoplanets with water, methane or carbon dioxide.
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"This system is unique because we are able to view the planet illuminated by its host star, but not see the host star at all," Maya Beleznay, a third-year PhD candidate at Stanford University in California, said as quoted.
"So we get a really pristine spectrum. And we can study this system in more detail than normal exoplanets," added Beleznay, who worked on modeling the shape of the planet and the geometry of its orbit.
This exoplanet is extremely unique, as no other planets have any detectable molecular carbon out of the approximately 150 planets that astronomers have studied inside and outside the solar system.
"The planet orbits a star that's completely bizarre - the mass of the Sun, but the size of a city," said Michael Zhang of the University of Chicago's, who is the principal investigator on this study.
"This is a new type of planet atmosphere that nobody has ever seen before. Instead of finding the normal molecules we expect to see on an exoplanet - like water, methane, and carbon dioxide - we saw molecular carbon, specifically C3 and C2."
Scientists are puzzled by PSR J2322-2650b's formation, as it doesn't fit known planetary formation mechanisms. Theories include crystallisation of carbon and oxygen in the planet's interior, but the absence of oxygen and nitrogen remains unexplained.
