Scientists have detected what they believe to be a neutron star spinning at an unprecedented speed, slower than any of the more than 3,000 radio-emitting neutron stars measured to date. This discovery challenges our current understanding of these cosmic objects, revealing a rotation that takes 54 minutes to complete.
Neutron stars, the ultra-dense remnants of a dead star, often rotate at astonishing speeds, completing a spin in a matter of seconds or even fractions of a second. However, this newly discovered star by an international team of astronomers breaks this norm.
What is a neutron star?
At the end of their lives, large stars use up all their fuel and explode in a spectacular 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, 1.4 times that of the Sun, It is contained within a radius of only 10 km.
Neutron stars have extremely strong magnetic fields and can spin at incredibly fast speeds, in some cases several times per second. This rapid spin, along with their powerful magnetic fields, can turn them into pulsars, that emit beams of electromagnetic radiation from their magnetic poles. When these beams pass the Earth, they can be detected as regular pulses of radio waves, visible light, x-rays or gamma rays, depending on the energy of the pulsar.
Could it be something else?
The unexpected radio signal coming from the stellar object traveled approximately 16,000 light years to reach Earth. The nature of the radio emission and the rate at which the rotation period changes suggest that it is a neutron star.
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The location of the ASKAP J1935+2148 in parameter space, which is frequently used to classify different types of pulsars, is consistent with other known long-period sources. It is located in the “valley of death” of pulsars, where no detectable radio signals are expected, challenging accepted theories of radio emission through rotation slowing.
However, researchers do not rule out the possibility that it is an isolated white dwarf with an extraordinarily strong magnetic field. The absence of other highly magnetic white dwarfs nearby makes the neutron star explanation more plausible.
Further investigation is required to confirm the nature of the object, But either scenario promises to provide valuable insights into the physics of these extreme objects.. The findings could make scientists reconsider their decades-old understanding of neutron stars, or white dwarfs; how they emit radio waves and what their populations are in our galaxy, the Milky Way.
ASKAP radio telescope
The discovery was made using CSIRO’s ASKAP radio telescope in the Wajarri Yamaji Territory in Western Australia, which can observe a large part of the sky at once, capturing things that researchers are not even looking for.
The research team was simultaneously monitoring a gamma ray source and looking for a fast radio burst when they detected the object slowly blinking in the data.
Manisha Caleblead author and member of the Institute of Astronomy at the University of Sydney, explained: “What is intriguing is how this object shows three distinct emission states, each with completely different properties. The MeerKAT radio telescope in South Africa played a crucial role in the distinction between these states. If the signals did not come from the same point in the sky, we would not have believed that it was the same object producing these different signals.”
