A research team from Ohio State University discovered one of the smallest black hole located approximately 1,500 ly from planet Earth, and that makes it, according to an official statement issued by the university on April 21, the closest black hole to Earth discovered Until now, they nicknamed it ‘the Unicorn’.
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.
To reach those results, which were accepted for publication in the Monthly Notices of the Royal Astronomical Society, this team examined a red giant orbiting the unicorn black hole with 3 telescopes, which are the Kelt Observatory in the state of Arizona, USA, the “ASAS” observatory in Chile, and the “TESS” satellite of NASA.
When researchers analyzed that data, they noticed something they couldn’t see appeared to be orbiting the red giant, causing the light from that star to change in intensity and appearance at various points around the orbit.
Something, they realized, was tugging at the red giant and changing its shape. That pulling effect, called a tidal distortion, offers astronomers a signal that something is affecting the star.
One option was a black hole, but it would have to be small – less than five times the mass of our sun, falling into a size window that astronomers call the “mass gap.” Only recently have astronomers considered it a possibility that black holes of that mass could exist.
“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, chair of Ohio State’s astronomy department and university distinguished scholar. “The simplest explanation is that it’s a black hole – and in this case, the simplest explanation is the most likely one.”
The most striking in these results is the mass of this new black hole, it is only equal to 3 times the sun mass, which means that it is also the smallest black holes discovered so far, and it falls into a completely new class of black holes that requires further study.
Since the discovery of the first black hole in our Milky Way galaxy, which was called Chicken X-1, a large number of researchers have been interested in searching for these strange objects in the aspects of our galaxy and studying them, and now we know that there are tens of them, and astronomers think that the Milky Way contains 10 Millions to a billion black holes.