'The Unicorn': One of the smallest and closest black holes to Earth has been discovered

Illustration of the Unicorn and its companion red giant star. (Lauren Fanfer/Ohio State/Handout)

TORONTO — Scientists have discovered one of the smallest black holes in our galaxy - and the closest one to Earth – and have named it “the Unicorn.”

Astronomers found the Unicorn approximately 1,500 light years away and gave it that nickname because of its rarity and its discovery amongst the Monoceros constellation, according to a release from Ohio State University. Monoceros is Greek for unicorn.

The findings, published in the April edition of journal Monthly Notices of the Royal Astronomical Society, outlines how the Unicorn is about three times the mass of our sun, considered small for a black hole, and appears to be the companion to a red giant star. “Companion” means the two are connected by gravity.

“When we looked at the data, this black hole – the Unicorn – just popped out,” said lead author Tharindu Jayasinghe in the release.

The red giant star the Unicorn is the companion of was previously well-documented by telescopes run by Ohio State and NASA, but its data had not been analyzed thoroughly, the release said.

When Jayasinghe and other researchers examined the red giant’s data, they noticed something appeared to be orbiting the star, causing the light from the star to change in intensity and appearance at various points around the orbit. The pulling effect, which is called “tidal distortion,” is usually a signal that something is affecting the star – in this case, a small black hole.

“Just as the moon’s gravity distorts the Earth’s oceans, causing the seas to bulge toward and away from the moon, producing high tides, so does the black hole distort the star into a football-like shape with one axis longer than the other,” said Todd Thompson, co-author of the study and chair of Ohio State’s astronomy department, in the release.

Studying black holes and neutron stars allows scientists to learn more about the way stars form and die.

“I think the field is pushing toward this, to really map out how many low-mass, how many intermediate-mass and how many high-mass black holes there are, because every time you find one it gives you a clue about which stars collapse, which explode and which are in between,” Thompson said.