The world of astrophysics has been shaken by the discovery of the exoplanet PSR J2322-2650b, as it does not fit any known formation models recorded so far. Located 2,055 light-years away, this world orbits a millisecond pulsar and has a molecular carbon atmosphere that rotates in the opposite direction of its spin.
Thanks to JWST’s infrared technology, scientists have been able to observe a shape that appears to have been distorted by gravity, similar to that of a lemon, and extreme temperatures that exceed expectations for its orbit. The results of this research, published in The Astrophysical Journal Letters, reveal that this “hot Jupiter” was not born as a planet but could be the remnant of a star whose characteristics blur the boundary between stellar and planetary bodies.
PSR J2322-2650b
Despite the multiple investigations and findings that have been conducted on the bodies residing in the Milky Way, the discovery of the system PSR J2322-2650b by NASA has left researchers completely stumped, unable to fully solve the mystery. “This was an absolute surprise,” says astronomer Peter Gao of the Carnegie Earth and Planets Laboratory. “I remember that after obtaining the data, our collective reaction was ‘What the hell is this?'” It was first detected in 2017, when irregularities were reported in the radio pulses of its host star, PSR J2322-2650: a millisecond pulsar that rotates every 3.46 milliseconds.
These alterations revealed the presence of a mass equivalent to 80% of Jupiter that completes an orbit every 7.8 hours. It was when the James Webb Space Telescope came into play that they were able to observe that, by operating in the infrared spectrum, the telescope could block the radio and gamma glare from the star to capture a “pristine” spectrum of the planet. According to astronomer Maya Beleznay from Stanford University, “This system is unique because we are able to see the planet illuminated by its host star, but we don’t see the host star at all. So we get a truly pristine spectrum. And we can study this system in greater detail than normal exoplanets”.
Why is it so characteristic?
The gravitational force of the pulsar has caused its mass to stretch into an elliptical shape, similar to a football or a lemon. Its atmosphere has been heated by gamma radiation to a scorching 1,900 Kelvin (1,630 degrees Celsius), and it displays a phenomenon never seen before: winds circulating to the west, opposite to the planet’s eastward rotation.
On the other hand, its chemical composition is also striking. Instead of water or methane, the air contains molecular carbon vapor (C2 and C3). According to astronomer Michael Zhang from the University of Chicago, “it is very difficult to imagine how such an extremely carbon-rich composition is obtained. It seems to rule out all known formation mechanisms”.
What is the final verdict?
The answer to the entire enigma surrounding this discovery might lie in the system’s past. Zhang and his team theorize that PSR J2322-2650b was originally a helium star. In a process similar to that of “black widow” pulsars, the neutron star would have devoured its companion until reducing it to an inert core.
On the other hand, astrophysicist Roger Romani from Stanford University and the Kavli Institute for Particle Astrophysics and Cosmology explains that “As the companion cools, the mixture of carbon and oxygen inside begins to crystallize. Pure carbon crystals float upwards and mix with helium, and that’s what we see. But then something has to happen to preserve oxygen and nitrogen. And that’s where the controversy lies.” Faced with this scenario of doubts and open questions, he added “It’s nice not to know everything. I am eager to learn more about the strangeness of this atmosphere. It’s great to have a puzzle to explore”.
Frequently asked questions
Why does the planet PSR J2322-2650b look like a lemon?
Because of the immense gravitational force of its star (a millisecond pulsar). Being so close and orbiting every 7.8 hours, gravity stretches the planet’s mass, giving it an elliptical shape similar to a football.
What anomalies does its atmosphere have?
Its atmosphere is made of molecular carbon vapor instead of water or methane, and it heats up to 1,900 Kelvin. Additionally, its winds travel westward, opposite to the planet’s own rotation, a phenomenon never seen before.
What is the origin of this strange world?
Scientists believe it is not a real planet, but the remnants of a helium star devoured by the pulsar. According to Roger Romani, as it cooled, the carbon inside crystallized and floated to the surface, creating this strange astronomical ‘puzzle.’