Not only is it rare in its genre, it’s the closest. The smallest hole recorded has just been discovered. They called it the “unicorn”. In part because the unicorn is in the constellation. But also because it is rare and unique.
It is roughly three times the mass of the sun. While it sounds like a lot, it’s a tiny size for a black hole. There are very few black holes of this mass in our universe. Another feature that makes it special is its location. It is 1,500 light years from Earth, still in the Milky Way.
It was discovered by Tharindu Jayasinghe, a graduate student in astronomy at Ohio State University. Until then, the black hole was hiding in sight.
“That black hole, the unicorn, just appeared,” said Jayasinghe. He is the lead author of research published by the Royal Astronomical Society on the subject.
Scientists cannot see the black hole. They are dark and invisible to the tools astronomers use to measure light. What you can see in this case is the star that accompanies it. The red giant, attached to the hole by gravity, is a well-documented star.
The astronomers noticed that something appeared to be orbiting the red giant. And the light of this star changed in intensity and appearance. So detailed Ohio University.
‘The moon’s gravity distorts the Earth’s oceans. The seas bulge towards and away from the moon, creating high tides. It’s similar: the black hole distorts the star much like a soccer ball. Produces one wave longer than the other. The simplest explanation is that it is a black hole. In this case, the simplest explanation is the most likely, ”said Todd Thompson. He is the chairman of the university’s astronomy department.
The smallest hole in history surprised science. No black hole with less than five solar masses was known.