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Mysterious object found in Milky Way: Black hole or neutron star?

An artist’s impression of the system assuming that the massive companion star is a black hole. The brightest background star is its orbital companion, the radio pulsar PSR J0514-4002E. The two stars are separated by 8 million km and circle each other every 7 days. (Credit: Daniëlle Futselaar)

(NewsNation) — A team of astronomers have found a new and unknown object in the Milky Way galaxy that could shed light on the formation of black holes.

The object could be an actual black hole, or it might not. Its mass is heavier than the heaviest known neutron star while simultaneously lighter than the lightest known black hole.


Whatever the object is, it’s living in what’s known as the “black hole mass gap,” researchers wrote in the study published Thursday in the journal Science. It was found orbiting a radio pulsar, a type of neutron star that spins rapidly and shines beams of radio light.

“Either possibility for the nature of the (object) is exciting,” Ben Stappers, professor of astrophysics at the University of Manchester, said in a news release. “A pulsar–black hole system will be an important target for testing theories of gravity and a heavy neutron star will provide new insights in nuclear physics at very high densities.”

Researchers concluded the object was formed by the merger of two other neutron stars, the collapsed cores of supergiant stars.

Neutron stars themselves can collapse, and when they do, it’s believed they can become black holes — objects with such gravitational force that not even light can escape them. The mass of most observed black holes is about five times the mass of the Sun, but they can be as light as 2.2 times the mass of the Sun.

The newly identified object, discovered by the MeerKAT Radio Telescope, is between 2.09 and 2.71 solar masses. The nature of objects within this so-called “mass gap” is unknown, and the discovery could help astronomers learn more about such objects.

“The ability of the extremely sensitive MeerKAT telescope to reveal and study these objects is a enabling a great step forward,” Stappers said.

Astronomers found the object while looking at a cluster of stars known as NGC 1851, an incredibly dense collection of old stars. They detected those beams of light coming from the radio pulsar, which spins more than 170 times a second and produces a rhythmic pulse like ticks on a clock.

The mass of both objects was calculated by measuring those ticks.

“Observations … showed that the (object) has a mass that was simultaneously bigger than that of any known neutron star and yet smaller than that of any known black hole, placing it squarely in the black-hole mass gap,” the news release states.

While astronomers were not able to definitely classify the object as either a neutron star or black hole, its discovery should open the door to studying the properties of extremely dense objects in the universe.

“We’re not done with this system yet,” said Arunima Dutta, one of the study’s co-authors. “Uncovering the true nature of the (object) will (be) a turning point in our understanding of neutron stars, black holes and whatever else might be lurking in the black hole mass gap.”