1st super-fast pulsar found snacking on its companion in far-flung star cluster

An artist's impression of a millisecond pulsar and its stellar companion.

Using FAST, the researchers observed two eclipsing events in the binary system, when one object passed in front of the other from Earth's point of view. One eclipse lasted around 5,000 seconds, and the second, which arrived between 1,000 and 2,000 seconds later, lasted for 500 seconds, according to the study. M92A is known as a millisecond pulsar, a souped-up version of the slightly slower-moving pulsar.

Ever since the discovery of the very first pulsar in 1967 by astronomer Jocelyn Bell Burnell, then a graduate student at the University of Cambridge, astronomers have uncovered thousands of these stellar speedsters in the Milky Way alone, with some clustering in the galactic plane — the region where the majority of a disk galaxy's mass lies — and others taking residence in the globular clusters that orbit our galaxy's center.

Ordinary pulsars spring into existence at the end of a massive star's life, peaking as a supernova explosion that leaves behind a stellar corpse known as a neutron star in its dusty wake. These neutron stars are small, weighing in at a mass that's equivalent to anywhere from one to several suns, crammed into a diameter of a mere 12.4 to 14.9 miles (20 to 24 kilometers). Yet what they lack in size, they make up for in speed, completing several rotations per second.

Millisecond pulsars, however, move much more quickly, powering hundreds of rotations per second by chewing on gas from a companion star that survived the supernova explosion, spilling material into a disk around the neutron star before falling onto it. During this process, the system is visible as an X-ray binary, according to the National Radio Astronomy Observatory. The neutron star then emerges as a millisecond radio pulsar when the accretion is over.

In globular clusters like Messier 92, things work a bit differently — stars are so tightly packed together that it's easier for ancient neutron stars to interact with other stars, allowing normal stellar binaries to be made. In the case of M92A, the pulsar hasn't found it too difficult to siphon material from its stellar companion, earning itself the reputation of being likened to a "redback spider" — a highly venomous Australian arachnid that often eats their male companions, the researchers said in a statement.

Also known as Tianyan, FAST is located in the Dawodang depression, a natural groove in the land of Pingtang County in southwest China's Guizhou. And this isn't the great radio telescope's first encounter with M92A, its 1,640-foot (500 meters) dish found tantalizing evidence for the pulsar on Oct. 9, 2017 — and with a light-collecting area that's twice that of the Arecibo Observatory in Puerto Rico, it's expected that FAST will improve our understanding of the pulsars that are kicking around the Milky Way galaxy, the researchers said in the statement.

Gemma was the former content director of Live Science, Space.com, science and space magazines How It Works and All About Space, history magazines All About History and History of War. She is the author of several books including "Quantum Physics in Minutes", "Haynes Owners’ Workshop Manual to the Large Hadron Collider" and "Haynes Owners’ Workshop Manual to the Milky Way". She holds a degree in physical sciences, a master’s in astrophysics and a PhD in computational astrophysics.