About 15,000 light years away, in the constellation , a perplexing object is emitting signals into space. It pulses in both X-ray and radio frequencies every 44 minutes, a behavior unlike anything astronomers have previously observed. This object could be a , the remnant of a star after it has used all of its nuclear fuel. Alternatively, it could be a , which is a neutron star possessing an extremely strong magnetic field. However, it might be neither of those.
“Astronomers have observed countless stars using various telescopes, but none have exhibited this behavior,” stated astronomer Ziteng Wang from Curtin University in Australia, in a that accompanied the May 28 release of a detailing the object. Wang was the lead author of the study. “Discovering a new type of stellar behavior is truly exciting.”
What exactly is this mysterious object, known technically as ASKAP J1832, and how common are such objects?
ASKAP J1832 is not the only object in the universe to emit regular energy flashes. also do this. However, pulsars flash much more rapidly than ASKAP J1832, typically in milliseconds to seconds. In 2022, astronomers identified a category of objects called , which, like ASKAP J1832, emit radio wave flashes on the order of tens of minutes. To date, 10 such objects have been discovered, but none are identical to ASKAP J1832, which is also the first to emit X-rays.
Furthermore, ASKAP J1832’s emissions have changed over time. During an observation using NASA’s orbiting in February 2024, the object was generating substantial X-rays and radio waves. However, during a follow-up observation six months later, the radio waves were 1,000 times weaker, and no X-rays were detected. This presented a puzzle.
“We considered various possibilities involving neutron stars and white dwarfs, either alone or with companion stars,” said co-author Nanda Rea from the Institute of Space Sciences in Barcelona, Spain, . “Currently, nothing perfectly aligns, but some ideas seem more promising than others.”
One of these ideas is the magnetar, but this doesn’t entirely fit due to ASKAP J1832’s bright and variable radio emissions. The white dwarf remains a possibility, but to generate the energy it does, ASKAP J1832 would need to be orbiting another body in a binary system. So far, this second body has not been found. From Earth, ASKAP J1832 appears to be located in a , which is a cloud of hot gas and high-energy particles remaining after a star’s explosive death. However, the paper’s authors concluded that the remnant is merely in the foreground, with ASKAP J1832 in the background, similar to a cloud drifting in front of the sun.
For now, the object remains an enigma that will be further investigated. “Discovering a mystery like this is not frustrating,” said co-author Tong Bao from the Italian National Institute for Astrophysics, in a statement. “It’s what makes science exciting.”
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