Neutron stars typically rotate at fast speeds, taking just seconds or even a fraction of a second to fully spin on their axis. However, a neutron star labeled ASKAP J1935+2148 defies this rule, emitting radio signals on a comparatively leisurely interval of 53.8 minutes.
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An artist’s impression of a neutron star. Image credit: Sci.News.
“In the study of radio emitting neutron stars we are used to extremes, but this discovery of a compact star spinning so slowly and still emitting radio waves was unexpected,” said University of Manchester’s Professor Ben Stappers.
“It is demonstrating that pushing the boundaries of our search space with this new generation of radio telescopes will reveal surprises that challenge our understanding.”
At the end of their life, large stars use up all their fuel and explode in a spectacular blast called a supernova.
What remains is a stellar remnant called a neutron star, made up of trillions of neutrons packed into a ball so dense that its mass is 1.4 times that of the Sun is packed into a radius of just 10 km.
The unexpected radio signal from ASKAP J1935+2148 detected by the astronomers traveled approximately 16,000 light-years to Earth.
The nature of the radio emission and the rate at which the spin period is changing suggest it is a neutron star.Further research is required to confirm what the object is.
“This discovery relied on the combination of the complementary capabilities of ASKAP and MeerKAT telescopes as well as the ability to search for these objects on timescales of minutes while studying how their emission changes from second to second,” said Dr. Kaustubh Rajwade, an astronomer at the University of Oxford.
“Such synergies are allowing us to shed new light on how these compact objects evolve.”
ASKAP J1935+2148 was detected CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country in Western Australia.
“What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others,” said Dr. Manisha Caleb, an astronomer at the University of Sydney.
“The MeerKAT radio telescope in South Africa played a crucial role in distinguishing between these states.”
“If the signals didn’t arise from the same point in the sky, we would not have believed it to be the same object producing these different signals.”
“Until the advent of our new telescopes, the dynamic radio sky has been relatively unexplored,” said University of Sydney’s Professor Tara Murphy.
“Now we’re able to look deeply, and often, we are seeing all kinds of unusual phenomena.”
“These events give us insights into how physics works in extreme environments.”
The discovery is described in a paper in the journal Nature Astronomy.
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M. Caleb et al. An emission-state-switching radio transient with a 54-minute period. Nat Astron, published online June 5, 2024; doi: 10.1038/s41550-024-02277-w
