In my recent post I have been talking about the universe and the several forces and objects that inhabit the universe and that are constantly a motive of study and curiosity among scientists, however there is no doubt that the most curious things that generate curiosity and theories are the black holes; extremely mysterious objects that have triggered all kinds of theories, objects that recently we could see in a photograph that brought us much closer to understand how these universal voids are able to suck everything in their path and where a lot of forces converge.
So, don't waste more time and let's begin
A black hole is essentially a region of space, inside which there is a concentration of mass so high that generates a gravitational field so immense that no material particles can escape, not even light can.
As I mentioned in my post about the Pulsars, black holes are also formed from the gravitational collapse of a star.
This collapse occurs as a result of the consumption of fuel in the core of a star. To understand it better we must understand that in a star it compresses matter and raises its temperature to the point where a nuclear fusion reaction begins. In this fusion reaction the hydrogen atoms are colliding forming helium and releasing a lot of energy, this energy maintains a balance between gravity and radiation, and therefore the star remains stable, but when it reaches the point where it is no longer possible to perform the process of nuclear fusion the star will simply explode and become something else.
As a curious fact, it should be noted that stars whose mass is larger than the sun's pressure can fuse heavier elements such as iron, but since the fusion of iron does not release energy, the levels of this element will increase in the nucleus of the star until the gravity increases exponentially and the balance between radiation and gravity is broken so that consequently it will cause the nucleus to collapse causing the star to implode creating a supernova.
After a supernova occurs, depending on the mass of the star, a white dwarf, a neutron star or if the star had a huge mass a black hole.
A remarkable fact about black holes is that according to Stephen Hawking
Black holes are not totally "black" because they emit small amounts of radiation in an effect that he calls Hawking radiation and in which he also conclude that the smaller the black hole, the greater the amount of radiation.
Types of black holes
After being clear about how black holes are essentially born, the next thing to know is that black holes are classified mainly according to their mass and that these can be:
- Black holes of stellar mass, these black holes are formed by the gravitational collapse of a massive star whose mass is between 20 to 70 solar masses.
- Supermassive black holes, These black holes are the largest. The mass of these black holes would far exceed one million solar masses. In fact, according to various studies, it is believed that in the center of the Milky Way there is a black hole called Sagittarius A, and that like the Milky Way, all galaxies would have a supermassive black hole in the center.
- Medium black holes, In this case, this type of black holes originates mainly from the supernova experienced by a giant or supergiant star, however, the size of the resulting black hole would be approximately similar to that of the earth but with a mass infinitely greater than from the earth.
- Small black holes, Not all black holes necessarily have to be gigantic and it is believed that black holes may exist as small as atoms, but that nevertheless, they could have a mass as big as a mountain.
In a certain way until now, observing a black hole is impossible because if hypothetically we could know exactly where to look, what we would see would really be the event horizon. Because the event horizon is a kind of border where there is a gravitational field so large that the only way out of it is to overcome the speed of light, in short everything that crosses the events horizon never comes out again.
This is why, when we refer to a black hole we refer to a singularity, since we don't know exactly how it looks, but theoretically it is a place where the density is infinite, that is to say, that the whole mass of the black hole is in an area of space that does not occupy any surface or volume. This fact is the reason why the black holes absorb everything that is close to them, due to the immense gravity field that covers them.
The black hole closest to the earth.
Maybe you, like many people at some point, have wondered what is the risk of the earth being swallowed by a black hole at some point, let me clarify that at least for now that is unlikely to happen since the black hole more close to the earth is believed to be the Cygnus X-1, a black hole of approximately 15 solar masses and which is in a binary system, that's mean that it orbits around a blue supergiant star.
A curious fact about this black hole is that the matter expelled by the star forms an accretion disk that orbits around the black hole and reaches temperatures of millions of degrees Kelvin.
The system of Cygnus X-1 is about 8,124 light-years from Earth, so as I mentioned earlier it is unlikely that the earth is affected by it in the near future.