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Scientists discover ‘highly unusual’ slow-spinning star

The star, identified using a unique telescope, challenges existing models of neutron star behavior.

(CN) — Scientists discovered what they believe could be a neutron star spinning slower than any previously measured, providing new insights into the mysterious life cycles of stellar objects.

Australian scientists from the University of Sydney and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) detected what is likely a neutron star with an unprecedentedly slow spin. They describe their findings in research published Monday in Nature Astronomy.

According to lead author Manisha Caleb from the University of Sydney, no other radio-emitting neutron star — among the over 3,000 discovered so far — has been found rotating so slowly.

“It is highly unusual to discover a neutron star candidate emitting radio pulsations in this way,” Caleb said in a press release accompanying the research. “The fact that the signal is repeating at such a leisurely pace is extraordinary.”

This star emits radio light at a rate too slow to fit with current models of radio neutron star behavior, providing new insights into the complex life cycles of stellar objects.

According to the research, neutron stars form when massive stars, about 10 times the mass of the sun, use up their fuel and explode in a supernova. The remnants are incredibly dense, packing 1.4 times the mass of Earth's sun into a sphere just 20 kilometers across.

These stars typically rotate rapidly, taking just seconds or fractions of a second to complete a spin. However, the newly discovered neutron star repeats its signal in a period just shy of one hour.

The scientists made their discovery using CSIRO’s ASKAP radio telescope on Wajarri Yamaji Country in Western Australia. ASKAP’s wide field of view allows it to capture unexpected phenomena.

“We were simultaneously monitoring a source of gamma rays and seeking a fast radio burst when I spotted this object slowly flashing in the data,” CSIRO scientist and co-lead author Emil Lenc said in the release.

According to Lenc, ASKAP’s unique design was a critical factor in making this discovery possible.

“ASKAP is one of the best telescopes in the world for this sort of research, as it is constantly scanning so much of the sky, allowing us to detect any anomalies," he said.

The origin of such a long-period signal has yet to be confirmed. Two types of stars are prime suspects: white dwarfs and neutron stars. 

“What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others,” Caleb said in the release.

The MeerKAT radio telescope in South Africa played a crucial role in distinguishing 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.”

According to the research, while a highly magnetic isolated white dwarf could produce the observed signal, it is surprising that no such nearby white dwarfs have been discovered.

A neutron star with extreme magnetic fields would also explain the emissions. But researchers haven’t ruled out the possibility that the object is part of a binary system with a neutron star or another white dwarf.

More research is needed to confirm whether the object is a neutron star or white dwarf. Regardless, it will provide valuable insights into the physics of these extreme objects.

“It might even prompt us to reconsider our decades-old understanding of neutron stars or white dwarfs–how they emit radio waves and what their populations are like in our Milky Way galaxy,” Caleb said in the release.

Professor Tara Murphy, head of the School of Physics at the University of Sydney, highlighted the significance of the slow-spinning star, which challenges existing theories and opens new avenues for understanding cosmic objects.

“Until the advent of our new telescopes, the dynamic radio sky has been relatively unexplored,” Murphy said in a statement. “Now we're able to look deeply, and often, we are seeing all kinds of unusual phenomena.”

Categories / Science

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