Neutron stars, the dense remnants of a dead star, typically rotate at extremely high speeds, taking just seconds or even less to fully spin on their axis. However, the newly discovered neutron star, identified by an international team of astronomers, emits radio signals at an interval of 54 minutes.
The team was led by Dr. Manisha Caleb at the University of Sydney and Dr. Emil Lenc at CSIRO, Australia's national science agency, and includes scientists at The University of Manchester and the University of Oxford. The results, published in the journal Nature Astronomy, provide new insights into the life cycles of stellar objects.
Ben Stappers, Professor of Astrophysics at The University of Manchester, said, "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. 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 supernova. What remains is a stellar remnant called a neutron star, composed of trillions of neutrons packed into a ball so dense that its mass is 1.4 times that of the Sun within a radius of just 10 km.
The unexpected radio signal from the stellar object detected by the scientists 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. However, the researchers have not ruled out the possibility of it being an isolated white dwarf with an extraordinarily strong magnetic field. The absence of other nearby highly magnetic white dwarfs makes the neutron star explanation more plausible.
Further research is required to confirm the object's nature, but either scenario promises to provide valuable insights into the physics of these extreme objects.
The findings could lead scientists to reconsider their understanding of neutron stars or white dwarfs, how they emit radio waves, and what their populations are like in our Milky Way galaxy.
Dr. Kaustubh Rajwade, an Astronomer at the University of Oxford, said, "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! Such synergies are allowing us to shed new light on how these compact objects evolve."
The discovery was made using CSIRO's ASKAP radio telescope in Western Australia, which can see a large part of the sky at once, allowing it to capture unexpected phenomena. The research team was monitoring a source of gamma rays and seeking a fast radio burst when they spotted the object slowly flashing in the data.
Lead author Dr. Manisha Caleb from the University of Sydney Institute for Astronomy said, "What is intriguing is how this object displays three distinct emission states, each with properties entirely dissimilar from the others. 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."
The origin of such a long-period signal remains a mystery, with white dwarfs and neutron stars being the prime suspects. Further investigations will continue to deepen our understanding of these enigmatic objects.
Research Report:An emission state switching transient with a 54-minute period
Related Links
University of Manchester
Stellar Chemistry, The Universe And All Within It
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