Astronomers have detected a peculiar signal from deep within our galaxy, leaving scientists perplexed and searching for answers. The origin of this mysterious signal is a neutron star named ASKAP J193505.1+214841.0 (ASKAP J1935+2148 for short), situated approximately 15,820 light-years from Earth within the Milky Way’s plane.

Despite identifying the source, the signals themselves remain unlike any observed before. This neutron star exhibits alternating periods of intense pulses, weak pulses, and complete silence, presenting a puzzling scenario for astronomers. According to a team led by astrophysicist Manisha Caleb from the University of Sydney, the enigmatic behavior of ASKAP J1935+2148 challenges our current understanding of neutron star evolution.

Neutron stars are the remnants of stars with a mass range between eight and thirty times that of our Sun. Following a supernova explosion, the star’s outer layers are expelled, leaving behind a core that collapses under gravity into an extremely dense object. This remnant, up to 2.3 times the mass of the Sun but only about 20 kilometers (12 miles) across, can manifest in several forms.

Varieties of Neutron Stars

Neutron stars can appear in various states. Some remain relatively inactive, while others, known as pulsars, emit beams of radio waves from their poles, rotating and flashing like cosmic lighthouses. Magnetars, another type, possess exceptionally strong magnetic fields that can cause the star to jerk and erupt due to the magnetic tension.

In some rare instances, neutron stars can exhibit characteristics of more than one type, indicating potential evolutionary stages among these celestial objects. However, pulsars, magnetars, and basic neutron stars usually display relatively consistent behaviors.

The Case of ASKAP J1935+2148

ASKAP J1935+2148 defies these norms. Initially discovered by chance during unrelated observations, further studies using the Australian Square Kilometre Array Pathfinder (ASKAP) and the MeerKAT radio telescope in South Africa provided more insight. The team also analyzed prior ASKAP data covering the same region of the sky.

They uncovered that ASKAP J1935+2148 exhibits a consistent pulsation period of 53.8 minutes, yet this regularity is the only typical aspect of its behavior. One pulsation mode is extraordinarily bright and highly polarized, while another phase shows no measurable pulsations at all. When the pulsations resume, they are 26 times dimmer and circularly polarized.

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Similar Mysterious Objects

This discovery adds to a growing list of strange objects emitting repeating signals in the southern sky. Each object behaves uniquely, yet they might share a connection. For instance, GLEAM-X J162759.5-523504.3, near the galactic center, emitted bright flashes for three months before becoming silent. Another object, GPM J1839-10, acts like an unusually slow pulsar with five-minute bursts every 22 minutes. Additionally, GCRT J1745-3009, located near the galactic center, pulses every 77 minutes.

While the exact nature of these objects remains uncertain, neutron stars are a likely explanation. Caleb and her team propose that ASKAP J1935+2148 might act as a bridge between these various states, with differences in pulsation modes potentially linked to magnetospheric changes. This suggests these objects could form a new class of magnetars, possibly evolving into pulsars.

Insights into Neutron Star Evolution

“ASKAP J1935+2148 is probably part of an older population of magnetars with long spin periods and low X-ray luminosities, yet magnetized enough to produce coherent radio emission,” the researchers noted in their study.

Understanding these previously unexplored aspects of neutron stars could provide a more comprehensive picture of their evolution. Studying ASKAP J1935+2148 and similar objects may unlock critical insights into the lifecycle and behavior of neutron stars, further expanding our knowledge of these enigmatic cosmic entities.

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