Surely when you think of a black hole, emptiness comes to mind, but in reality, black holes are the densest objects in the Universe. In this article we are going to reveal some of the mysteries of these celestial objects, such as what is inside a black hole and how it is formed. We’ll even find out how a supermassive black hole differs from the rest.
WHAT IS A BLACK HOLE?
First of all we must know what a black hole is. According to NASA, a black hole is an astronomical object that has such a strong gravitational pull that nothing, not even light, can escape from it. Hence its revealing name.
Because they do not emit light, black holes are invisible. However, it is possible to observe the radiation through the electromagnetic spectrum that is produced when matter is attracted to the black hole.
Furthermore, black holes are finite, that is, they have a certain size. The spherical surface of the black hole is called the “event horizon”. This is the one that surrounds the body of the hole and defines the limit from which the matter and radiation, which are inside the black hole, are trapped and cannot get out.
Black holes are normally quite small. Think that, after all, a black hole is formed with part of the remains of stars in extinction. However, appearances are deceiving because, due to its high density, a small black hole will have a much larger mass than stars of the same size.
HOW ARE BLACK HOLES FORMED?
As we said, in the past black holes were huge stars. In fact, they are considered to be 10 to 15 times larger than our Sun. As these giant stars reach the last phase of their lives, they explode in vast events known as supernovae.
In this explosion the star violently expels its outer layers into outer space. However, its core succumbs to gravitational pull.
And it is that these remains do not have enough strength to resist gravity, so the old star begins to fold back on itself, becoming more and more dense. After this process a black hole is formed.
It should be noted that not all stars become black holes, but only the most massive stars do. Many others end up becoming white dwarfs or neutron stars.
WHAT IS INSIDE A BLACK HOLE?
As we said, in the past black holes were huge stars. In fact, they are considered to be 10 to 15 times larger than our Sun. As these giant stars reach the last phase of their lives, they explode in vast events known as supernovae.
In this explosion the star violently expels its outer layers into outer space. However, its core succumbs to gravitational pull.
And it is that these remains do not have enough strength to resist gravity, so the old star begins to fold back on itself, becoming more and more dense. After this process a black hole is formed.
It should be noted that not all stars become black holes, but only the most massive stars do. Many others end up becoming white dwarfs or neutron stars.
TYPES OF BLACK HOLES
Black holes are normally classified based on the amount of mass. The most studied are: stellar-type black holes, with a mass between three and twelve times the mass of the Sun, and supermassive black holes.
One of the biggest differences between the two types of black holes is their evolution. Stellar-type black holes evolve rapidly. On the other hand, supermassive black holes, being larger, have a much slower evolution. This means that in order to achieve adequate monitoring of supermassive black holes, millions of years of study would be required, this being impossible for human life.
A supermassive black hole
The name of supermassive black hole is not chosen by chance, but these are really huge: they have a mass of between 10 and 100 billion suns. Its origin remains unclear, but what physicists suspect is that supermassive black holes inhabit the centers of massive galaxies, and when two of these galaxies merge, their central black holes merge, giving rise to a supermassive black hole.
The dimensions of this type of black hole is due to the fact that in the galaxy where they are found there is a lot of matter, which the black hole is trapping. This happens, for example, with the gas released by surrounding stars or other black holes. Added to this is that supermassive black holes have the ability to accumulate unlimited amounts of matter.
In the case of our Milky Way we can find a supermassive black hole, known as Sagittarius A*, which is located in the constellation Sagittarius, in the center of our galaxy. Lucky for us, this black hole is around 27,000 light-years from Earth. In 2022, scientists have managed to photograph this black hole for the first time, thus proving its existence.
Also recently, it has been possible to detect the pair of supermassive black holes closest to Earth, located specifically 89 million light years from our planet. Although it may seem like a long way, it far exceeds the previous record, which was 470 million light years from our planet.