Black holes are the sharks of the universe. People suffer from an unjustified fear of them, although you really need to try to get closer to at least one of them. Space is vast, and black holes, thousands of light years distant from our planet, are nothing more than small islands in the vast ocean of the universe. Therefore, those who wish to look at them will need a large telescope.
Sagittarius A
When it comes to black holes in the Milky Way galaxy, the first thing any astronomer would mention would be Sagittarius A (Sagittarius A). It lies at the very core of the Milky Way. Sagittarius A weighs 4 million times more than our Sun, but only 6,000 times more. But it's not the closest black hole to Earth. It is located at a distance of 26 thousand light years from our planet, therefore, in fact, it cannot be called our neighbor.
It is mentioned more often than others due to the fact that Sagittarius A is the closest black hole to Earth among supermassive stars, besides it is the only one of its kind within the Milky Way galaxy. Amongof all the other black holes in our galaxy, there is not one that would be heavier than the Sun by more than 15 times.
V616 Monocerotis
The closest black hole to Earth is V616 Monocerotis. It is located at a distance of 3 thousand light years from the Earth, its mass is about 9-13 times the mass of the Sun. The second closest to us is Cygnus X-1. It is located 6 thousand light years from Earth, its mass is 15 times that of the Sun. In third place is GRO J0422 +32. It's 7,800 light-years away from us, and it's also the smallest black hole ever discovered.
These three space monsters have something else in common besides being the three closest black holes to Earth. All three have satellites. It was thanks to the satellites that they were discovered. The black hole, pulling on the planet more and more, gradually begins to absorb it, but before the victim plunges beyond the event horizon, it heats up and begins to emit x-rays. X-ray tracking is the most efficient way to find black holes. Telescopes like NASA's Chandra are the ultimate black hole hunters. It was Chandra who first discovered V616 Monocerotis, the closest black hole to Earth.
Search difficulties
Black holes, as their name implies, are completely black. The gravitational field of a black hole is so powerful that it attracts and draws even light into itself. Given the overall blackness of space, this factor becomes significant.an obstacle when searching for sharks of the universe.
They distort space and time, so ideally one could look for them by the effect of microlensing - subtle deviations in the light of distant stars. But the chances of success are almost nil. This method will only work if the distant star and the black hole line up.
How many black holes are there?
Currently, we can estimate the number of black holes based on the number of supernovae. According to researchers, over the past million years, about 20 thousand star explosions have occurred in the Milky Way. With no tangible change in the number of stellar explosions over the past 12 billion years, there must be tens of millions of black holes lurking in the Milky Way.
The Milky Way is 100,000 light-years long and 1,000 light-years wide. This is approximately 7.86 trillion cubic light years. If we assume that there are only 1 million black holes in our galaxy, this means that there is one shark of the universe for every 125 light years. Obviously, this is a very rough assumption. In addition, black holes are far from being so evenly distributed in space.
Nevertheless, there are a huge number of black stars that have not yet been discovered. They won't be found overnight, but new amazing observations will undoubtedly give us the opportunity to learn a lot of interesting facts about black holes. It is quite possible that soonIn the future, V616 Monocerotis will lose its title as the closest black hole to Earth to some other terrible giant.
