The rotating space object, which was discovered in March 2018, radiated radiation three times an hour. In those moments, it became the brightest source of radio waves in our sky, and served as a celestial lighthouse.
Astronomers believe it could be the remnant of a collapsed star, either a dense neutron star or a dead white dwarf star, with a strong magnetic field – or it could be something completely different.
“This object appeared and disappeared within a few hours during our observations,” study lead author Natasha Hurley-Walker, an astrophysicist at Curtin University’s hub at the International Center for Radio Astronomy Research, said in a statement.
“It was completely unexpected. It was a little creepy for an astronomer because there’s nothing known in the sky that does. And it’s actually pretty close to us – about 4,000 light-years away. It’s in our galactic backyard.”
Curtin University PhD student Tyrone O’Doherty made the unusual discovery while using the Murchison Widefield Array telescope in the outback of Western Australia.
“It’s exciting that the source I identified last year has proven to be such a peculiar object,” O’Doherty said in a statement. “The MWA’s wide field of view and extreme sensitivity are perfect for overseeing the entire sky and discovering the unexpected.”
What’s left of the death of a massive star
Flattening space objects that appear to turn on and off are known as transients.
“When you study transients, you see the death of a massive star or the activity of the remnants it leaves behind,” study co-author Gemma Anderson, ICRAR-Curtin astrophysicist, said in a statement. “‘Slow transients’ – like supernovae – can appear within a few days and disappear after a few months. ‘Fast transients’ – like a type of neutron star called a pulsar – flash on and off within milliseconds or seconds.”
However, this new, incredibly bright object only lit for about one minute every 18 minutes. The researchers said their observations could match the definition of an ultra-long-period magnetar. Magnets usually flare up with the second, but this object takes longer.
“It’s a type of slowly rotating neutron star that has been predicted to exist theoretically,” Hurley-Walker said. “But no one directly expected to detect such one because we did not expect them to be so bright. Somehow, it converts magnetic energy into radio waves much more efficiently than anything we’ve seen before.”
The researchers will continue to monitor the object to see if it lights up again, and in the meantime, they are looking for evidence of other similar objects.
“Several demonstrations will tell astronomers whether this was a rare one-time event or a huge new population we had never noticed before,” Hurley-Walker said.