Ultra-Fast Pulsar Was Spotted Consuming its Pair in Distant Star Cluster Messier 92

China’s Five-hundred-meter Aperture Spherical Telescope (FAST) has captured fascinating images of Messier 92, a globular star cluster located about 27,000 light-years away from Earth in the constellation of Hercules.

The spinning and pulsating cosmic body, which has two other names, PSR J1717+4307A and M92A, forms one side of an eclipsing binary system in which it is pumping material from a stellar pair, as per a new study.

Another Kind of Pulsar

A research team led by Zhichen Pan and Li Di from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), which manages FAST, the world’s most massive radio telescope, has demonstrated that M92A rotates at a rapid speed of 316.5 rotations per second and co-orbits a star lighter than our Sun, with a weight of about 0.18 solar masses.

Using FAST, the team examined two eclipsing occurrences in the binary system, when one object flew in front of the other from Earth’s perspective. One eclipse took place for about 5,000 seconds, and the other one, which arrived between 1,000 and 2,000 seconds later, lasted for 500 seconds, the research says.

Messier 92 is known as a millisecond pulsar, a swollen version of the slower-moving pulsar. Millisecond pulsars are highly-magnetized neutron stars, which rotate at rapid speeds of less than 30 milliseconds, the Swinburne Astronomy Online Encyclopedia of Astronomy reports.

Globular cluster Messier 92, which resides 27,000 light-years away in Hercules constellation. [Image: ESA/NASA/Hubble]
Regular pulsars appear at the end of a large star’s life, springing into existence as a supernova explosion that leaves behind a stellar body called neutron star in its dusty shaping. These neutron stars are small, have little weight, and measure about 12.4 to 14.9 miles (120 to 24 kilometers). However, when it comes to speed, they manage to complete a few rotations per second.

If there is a magnetic field hidden around the neutron star, charged particles emitted by the star get hooked, making the star discharge electromagnetic radiation in a beam every few seconds. These flashes are known as pulsars.

Consuming its Companion

By comparison, millisecond pulsars move much more rapidly, completing hundreds of rotations per second by consuming gas from a pair star that survived the supernova explosion, emitting material into a disc around the neutron star before collapsing into it.

According to the National Radio Astronomy Observatory, The system is visible an X-ray binary throughout this process, with the neutron star ultimately appearing as a millisecond radio pulsar when the accretion completes.

In globular clusters like Messier 92, the mechanics are a bit different. Stars are so closely packed together that it’s easier for old neutron stars to engage with other stars, enabling regular stellar binary systems to form.

In the case of M92A, the pulsar had easily consumed material from its stellar pair, later on being likened to a ‘redback spider,’ which is a highly venomous Australian arachnid that usually eats their male partners, the scientists said in a statement.

Also known as Tianyan, FAST is located in the Dawodang depression, in the Pingtang County in southwest China’s province of Guizhou.

The research was published in The Astrophysical Journal Letters.

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