A new black hole has very recently been discovered near the center of our galaxy, the Milky Way. This black hole is special because it is an intermediate sized black hole, only 30,000 times the mass of our Sun and concentrated in a region smaller than our Solar System, making it incredibly dense. The proximity of this black hole to the supermassive black hole in the center of our galaxy is what will prove to be the most exciting part of this discovery. When this black hole is eventually consumed by our supermassive black hole known as Sagittarius A, it will support the theory that black holes can combine to form even larger black holes.
The research team at the National Astronomical Observatory of Japan discovered the black hole by observing the strange movements of a gas cloud 20 light years away from the Sagittarius A. They used ALMA (Atacama Large Millimeter/submillimeter Array) to observe the cloud and found it swirling around a massive invisible object. They hope that this revelation will lead to more intermediate black hole discoveries in our local universe.
If all of this information sounds intriguing but also a little daunting, here’s a little run down on the facts about black holes to put it all in perspective. A black hole is space where gravity pulls so much that nothing can get out, including light. This is what makes them invisible to us on Earth. The way we discover black holes is by observing the gravitational effects on the stars surrounding them. When stars are close to black holes, they emit a high energy light. Scientists believe that the smallest black holes were formed when the universe began and can be as small as the size of an atom.
Another type of black hole, which most people are familiar with, are stellar black holes. Stellar black holes are formed when a star dies. When a star dies, it runs out of fuel and it collapses in on itself and forms a supernova. A supernova is a star which is being blasted apart and its parts are being propelled into space. It will continue to collapse on itself and compress until it becomes a stellar black hole. These black holes are typically twenty times the mass of our sun. And don’t worry, our Sun will never become a black hole. It’s just too small. When small stars collapse, they simply become a new star like a white dwarf or neutron star.
The final type of black hole that we’re aware of is the supermassive black hole. Scientists believe that these black holes were formed at the same time as the universe around them. Nearly every mature galaxy like our own has a supermassive black hole at its core. All black holes grow as it consumes more of the galaxy around it, just as Sagittarius A will eventually consume this new black hole that was just discovered. There is still a lot to learn about black holes. The first black hole wasn’t actually discovered until 1971 even though they had been predicted by Albert Einstein in 1916. Scientists hope that we will discover even more intermediate black holes lurking across our galaxy, possibly hundreds of millions of them.