A lot of amazing things happen in space, as a result of which new stars appear, old ones disappear and black holes form. One of the magnificent and mysterious phenomena is the gravitational collapse that ends the evolution of stars.
Star evolution is a cycle of changes that a star goes through during its existence (millions or billions of years). When the hydrogen in it ends and turns into helium, a helium core is formed, and the space object itself begins to turn into a red giant - a star of late spectral classes, which has a high luminosity. Their mass can be 70 times the mass of the Sun. Very bright supergiants are called hypergiants. In addition to high brightness, they are distinguished by a short period of existence.
Essence of collapse
This phenomenon is considered the end point of the evolution of stars whose weight is more than three solar masses (the weight of the Sun). This value is used in astronomy and physics to determine the weight of other space bodies. Collapse occurs when gravitational forces cause huge cosmic bodies with large masses to collapse very quickly.
Stars weighing more than three solar masses haveenough material for long-term thermonuclear reactions. When the substance ends, the thermonuclear reaction also stops, and the stars cease to be mechanically stable. This leads to the fact that they begin to shrink towards the center at supersonic speed.
Neutron stars
When stars contract, it causes internal pressure to build up. If it grows strong enough to stop the gravitational contraction, then a neutron star appears.
Such a cosmic body has a simple structure. A star consists of a core, which is covered by a crust, and it, in turn, is formed from electrons and atomic nuclei. About 1 km thick, it is relatively thin compared to other bodies found in space.
The weight of neutron stars is equal to the weight of the Sun. The difference between them is that their radius is small - no more than 20 km. Inside them, atomic nuclei interact with each other, thus forming nuclear matter. It is the pressure from its side that does not allow the neutron star to shrink further. This type of star has a very high rotation speed. They are capable of making hundreds of revolutions in one second. The birth process begins from a supernova explosion, which occurs during the gravitational collapse of a star.
Supernovae
A supernova explosion is a phenomenon of a sharp change in the brightness of a star. Then the star begins to slowly and gradually fade away. Thus ends the last stage of the gravitationalcollapse. The whole cataclysm is accompanied by the release of a large amount of energy.
It should be noted that the inhabitants of the Earth can see this phenomenon only after the fact. The light reaches our planet long after the outbreak occurred. This caused difficulties in determining the nature of supernovae.
Neutron star cooling
After the end of the gravitational contraction that formed the neutron star, its temperature is very high (much higher than the temperature of the Sun). The star is cooling due to neutrino cooling.
Within a couple of minutes, their temperature can drop 100 times. Over the next hundred years - another 10 times. After the luminosity of a star decreases, the process of its cooling slows down significantly.
Oppenheimer-Volkov limit
On the one hand, this indicator displays the maximum possible weight of a neutron star, at which gravity is compensated by neutron gas. This prevents the gravitational collapse from ending in a black hole. On the other hand, the so-called Oppenheimer-Volkov limit is also the lower limit of the weight of a black hole, which were formed during stellar evolution.
Due to a number of inaccuracies, it is difficult to determine the exact value of this parameter. However, it is assumed to be in the range of 2.5 to 3 solar masses. At the moment, scientists claim that the heaviest neutron staris J0348+0432. Its weight is more than two solar masses. The weight of the lightest black hole is 5-10 solar masses. Astrophysicists claim that these data are experimental and concern only currently known neutron stars and black holes and suggest the possibility of the existence of more massive ones.
Black holes
A black hole is one of the most amazing phenomena that can be found in space. It is a region of space-time where the gravitational pull does not allow any objects to escape from it. Even bodies that can move at the speed of light (including quanta of light itself) are not capable of leaving it. Until 1967, black holes were called "frozen stars", "collapsers" and "collapsed stars".
A black hole has an opposite. It's called a white hole. As you know, it is impossible to get out of a black hole. As for the whites, they cannot be penetrated.
In addition to the gravitational collapse, the collapse in the center of the galaxy or the protogalactic eye can be the reason for the formation of a black hole. There is also a theory that black holes appeared as a result of the Big Bang, like our planet. Scientists call them primary.
There is one black hole in our Galaxy, which, according to astrophysicists, was formed due to the gravitational collapse of supermassive objects. Scientists claim that such holes form the core of many galaxies.
Astronomers in the United States suggest that the size of large black holes may be significantly underestimated. Their assumptions are based on the fact that in order for the stars to reach the speed with which they move through the M87 galaxy, located 50 million light years from our planet, the mass of the black hole in the center of the M87 galaxy must be at least 6.5 billion solar masses. At the moment, it is generally accepted that the weight of the largest black hole is 3 billion solar masses, that is, more than half as much.
Black hole synthesis
There is a theory that these objects can appear as a result of nuclear reactions. Scientists have given them the name quantum black gifts. Their minimum diameter is 10-18 m, and the smallest mass is 10-5 g.
The Large Hadron Collider was built to synthesize microscopic black holes. It was assumed that with its help it would be possible not only to synthesize a black hole, but also to simulate the Big Bang, which would make it possible to recreate the process of formation of many space objects, including the planet Earth. However, the experiment failed because there was not enough energy to create black holes.
