Printing of Askap artist J1839-0756, a neutron star emitting radio beams from his magnetic posts
James Josephides
A star collapsed at around 13,000 light years is so unusual that researchers who discovered it say that it should not exist.
It was detected for the first time in January 2024 by the ASKAP radiotelescope in Western Australia and is probably a kind of pulsar that has never been seen before.
When supermassive stars reach the end of their lives and explode in a supernova, the remains form a super dense object called neutron star. The pulsars are neutron stars that turn quickly, emitting radio waves from their magnetic poles when they turn. Most pulsars run at speeds of more than one revolution per second and we receive an impulse at the same frequency, each time a radio bundle points to us.
But in recent years, astronomers have started to find compact objects that have raised radio wave pulses at a much slower pace. This was disconcerted by scientists, who had thought that the flashing of radio waves should stop when the rotation slows over a minute for each rotation.
These slow skid objects are known as long -time radio transients. Last year, a team led by Manisha Caleb At the University of Sydney, Australia, announced the discovery of a transient with a 54 -minute period.
Now, Caleb and his colleagues say that a new object they found a year ago, named Askap J1839-0756, runs at a new record rate of 6.45 hours by rotation.
It is also the first transitional that has ever been discovered with an interpulce: a lower impulse halfway between the main pulses, coming from the opposite magnetic pole.
At first, the team thought that Askap J1839-0756 could be a white dwarf, a smaller star like our sun that is dead. “But we have 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,” said Joshua Leemember of the team at the University of Sydney.
Then, the team thought it could be a magnetar, a neutron star with a huge magnetic field – up to 10 billions of times more powerful than the strongest MRI machines of the earth.
A magnetar with a similar period of rotation of 6.67 hours has been found before, but so far, it has not emitted X -rays, not radio waves.
Caleb says that if the star is an isolated magnetar, it would be the first which emits in the frequency of radio waves with a slow period.
“This new object completely rewrites what we thought we knew about the radio emission mechanisms of neutron stars of the last 60 years,” explains Caleb. “It is certainly one of the strangest objects of recent times, because we did not think that these things existed. But now we find them. If it is a magnetar, it is certainly unique among the population of neutron stars.”
She says that the idea that pulsars stop emitting radio waves when they turn too slowly must be reconsidered.
“We have seen objects in recent years that seem to cross this death line, but they always emit on the radio (frequency),” explains Caleb. “So, they are like zombie stars where you do not expect them to be alive, but they are still alive, and they pulse.”
