Artist’s impression of ASKAP J1839-0756, a neutron star emitting beams of radio waves from its magnetic poles
James Josephides
A collapsed star round 13,000 gentle years away is so uncommon that the researchers who’ve found it say it shouldn’t exist.
It was first detected in January 2024 by the ASKAP radio telescope in Western Australia and is prone to be a type of pulsar that has by no means been seen earlier than.
When supermassive stars attain the top of their lives and explode in a supernova, the remnants kind a super-dense object known as a neutron star. Pulsars are neutron stars that spin quickly, emitting radio waves from their magnetic poles as they rotate. Most pulsars spin at speeds of a couple of revolution per second and we obtain a pulse on the identical frequency, every time a radio beam factors in the direction of us.
However in recent times, astronomers have begun to seek out compact objects that emit pulses of radio waves at a a lot slower fee. This has baffled scientists, who had thought that radio wave flashes ought to stop when the rotation slows to greater than a minute for every spin.
These slow-spinning objects are referred to as long-period radio transients. Final 12 months, a workforce led by Manisha Caleb on the College of Sydney, Australia, introduced the invention of a transient with a interval of 54 minutes.
Now, Caleb and her colleagues say a brand new object they discovered a 12 months in the past, named ASKAP J1839-0756, is rotating at a brand new report gradual tempo of 6.45 hours per rotation.
It’s also the primary transient that has ever been found with an interpulse: a weaker pulse midway between the principle pulses, coming from the other magnetic pole.
At first, the workforce thought that ASKAP J1839-0756 could be a white dwarf, a smaller star like our solar that has died. “But we’ve never seen an isolated white dwarf emitting radio pulses and our calculation suggests that it is too big to be an isolated white dwarf based on the properties of the pulse,” says Joshua Lee, a workforce member on the College of Sydney.
Subsequent, the workforce thought it could be a magnetar, a neutron star with an immense magnetic subject – as a lot as 10 trillion instances extra highly effective than the strongest MRI machines on Earth.
A magnetar with an identical rotation interval of 6.67 hours has been discovered earlier than, however, to this point, it has solely emitted X-rays, not radio waves.
Caleb says that if the star is an remoted magnetar, it could be the primary that emits within the radio wave frequency with a interval that’s this gradual.
“This new object is completely rewriting what we thought we knew about radio emission mechanisms from neutron stars of the last 60 years,” says Caleb. “It is definitely one of the weirdest objects in recent times, because we didn’t think these things existed. But now we’re finding them. If it is a magnetar, it is certainly unique amongst the neutron star population.”
She says the concept that pulsars stop emitting radio waves after they spin too slowly must be reconsidered.
“We’re seeing objects in recent years which seem to cross this death line, but they’re still emitting in the radio [frequency],” says Caleb. “So they’re like zombie stars where you don’t expect them to be alive, but they’re still alive, and they’re pulsing away.”
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