The black hole is the closest to Earth, among the smallest ever discovered

Scientists have discovered one of the smallest black holes recorded – and the closest to Earth found to date.

Researchers have named it “Unicorn”, partly because it is so far unique and partly because it was found in the constellation Monoceros – “Unicorn”. The findings are published in the journal Today, April 21 Monthly notifications from the Royal Astronomical Society.

“When I looked at the data, this black hole – the unicorn – just came out,” said lead author Tharindu Jayasinghe, a doctoral student in astronomy at Ohio State University and a presidential member in Ohio.

The unicorn is about three times the mass of our sun – small for a black hole. Very few black holes in this mass have been found in the universe. This black hole is 1,500 light-years away from Earth, still inside the Milky Way galaxy. And until Jayasinghe began to analyze it, it was essentially hiding from view.

The black hole appears to be a companion of a huge red star, which means that the two are connected by gravity. Scientists cannot see the black hole – they are, by definition, dark, not only visually, but also the instruments that astronomers use to measure light and other wavelengths.

But in this case, I can see the accompanying star of the black hole. That star had been well documented by telescope systems, including KELT, outside of Ohio; ASAS, the forerunner of ASAS-SN, now without Ohio, and TESS, a NASA satellite looking for planets outside our solar system. Data on this had been widely available, but had not yet been analyzed in this way.

When Jayasinghe and the other researchers analyzed this data, they noticed that something they could not see seemed to orbit the red giant, causing the light from that star to change in intensity and appearance at various points around the orbit.

They realized that something was pulling at the red giant and changing its shape. This firing effect, called tidal distortion, gives astronomers a signal that something is affecting the star. One option was a black hole, but it should be small – less than five times the mass of our sun, falling into a window of dimensions that astronomers call the “mass gap.” Only recently have astronomers considered it possible for black holes in that mass to exist.

“When you look at what we do differently, you find different things,” said Kris Stanek, co-author of the study, a professor of astronomy at Ohio State and a distinguished researcher. “Tharindu looked at this so many other people looked at it and instead of dismissing the possibility that it was a black hole, he said, ‘Well, what if it could be a black hole? ””

This interruption of the tides is produced by the tidal force of an unseen companion – a black hole.

“Just as the moon’s gravity distorts the Earth’s oceans, causing the sea to swell to and from the moon, producing high tides, so the black hole distorts the star in a football-like shape, with one axis longer than the other.” said Todd Thompson, co-author of the study, president of the Ohio State Department of Astronomy and a scholar. “The simplest explanation is that it’s a black hole – and in this case, the simplest explanation is the most likely.”

The speed of the red giant, the period of its orbit, and how the tidal force distorted the red giant told them the mass of the black hole, leading them to conclude that this black hole was about three solar masses, or three times that of the sun.

Over the past decade, astronomers and astrophysicists have wondered if they would find these black holes because the systems and approaches they used were not sophisticated enough to find them. Or, they wondered, did they simply not exist?

Then, about 18 months ago, many members of this research team in the state of Ohio, led by Thompson, published a scientific article in the journal Science, providing strong evidence that these types of black holes existed. This discovery motivated Jayasinghe and others, both in the state of Ohio and around the world, to seriously look for smaller black holes. And that assessment led them to Unicorn.

Finding and studying black holes and neutron stars in our galaxy is crucial for scientists studying space because it tells them about how stars form and die.

But finding and studying black holes is, almost by definition, difficult: individual black holes do not emit the same type of rays that other objects emit in space. As for scientific equipment, it is silent and electromagnetically dark. Most known black holes have been discovered because they interacted with an accompanying star, which created a lot of X-rays – and those X-rays are visible to astronomers.

In recent years, several large-scale experiments have been launched to try to locate smaller black holes, and Thompson said he expects to discover more “mass” black holes in the future.

“I think the field is heading towards this, to really identify how many small masses, how many intermediate masses and how many black holes with large masses, because every time you find one it gives you an idea of ​​what stars the collapse, which explodes and which are between them, “he said.

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