A lot of amazing things happen in spaceas 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, which ends the evolution of stars.
Stellar evolution is a cycle of change,traveled by a star during its existence (millions or billion years). When 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 have a short period of existence.
Essence of Collapse
Это явление считается конечной точкой эволюции 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 cosmic bodies. Collapse happens when gravitational forces force huge cosmic bodies with a large mass to shrink very quickly.
In stars weighing more than three solar masses, there areenough material for long-term thermonuclear reactions. When the substance ends, the thermonuclear reaction stops, and the stars cease to be mechanically stable. This leads to the fact that with supersonic speed they begin to shrink to the center.
Neutron stars
When the stars shrink, this results in internal pressure. If it grows with enough force to stop the gravitational contraction, then a neutron star appears.
Such a cosmic body has a simplestructure. The star consists of a core that covers the core, and it, in turn, is formed from electrons and atomic nuclei. Its thickness is about 1 km and is relatively thin when compared with other bodies found in space.
The weight of neutron stars is equal to the weight of the sun.The difference between them is that they have a small radius - no more than 20 km. Inside them, atomic nuclei interact with each other, thus forming nuclear matter. It is the pressure from her side that prevents the neutron star from shrinking further. This type of stars has a very high rotational speed. They are able to make hundreds of turns in one second. The process of birth begins from a supernova explosion, which arises during the gravitational collapse of a star.
Supernovae
Supernova explosion is a phenomenonsharp changes in star brightness. Further, the star begins to slowly and gradually fade away. So ends the last stage of gravitational collapse. The entire cataclysm is accompanied by the release of a large amount of energy.
It should be noted that the inhabitants of the earth can seethis phenomenon is only after the fact. Light reaches our planet after a long period after the outbreak. This has led to difficulties in determining the nature of supernovae.
Neutron star cooling
After the end of gravitational compression,which resulted in the formation of a neutron star, its temperature is very high (much higher than the temperature of the sun). The star cools due to neutrino cooling.
Within a couple of minutes their temperature maydrop 100 times. Over the next hundred years - another 10 times. After the star's luminosity decreases, its cooling process slows down significantly.
Oppenheimer-Volkov limit
On the one hand, this indicator displaysthe maximum possible weight of a neutron star, in which gravity is compensated by a neutron gas. This does not allow gravitational collapse to end with the appearance of a black hole. On the other hand, the so-called Oppenheimer-Volkov limit is at the same time the lower threshold of the weight of a black hole, which were formed in the course of stellar evolution.
Due to a number of inaccuracies it is difficult to determine the exactvalue of this parameter. However, it is assumed that it is in the range of 2.5 to 3 solar masses. At the moment, scientists say that the heaviest neutron star is 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
Черная дыра – это один из самых удивительных phenomena that occur in space. It is a region of space-time, where gravitational attraction does not allow any objects to leave it. Even bodies that can move at the speed of light (including the quanta of the light itself) are not able to leave it. Until 1967, black holes were called "frozen stars", "collapsars" and "collapsed stars."
The black hole has the opposite. It is called a white hole. As you know, it is impossible to get out of a black hole. As for whites, they cannot be penetrated.
Besides gravitational collapse, the causeblack hole formations can be a collapse in the center of the galaxy or the protogalactic eye. There is also a theory that black holes appeared as a result of the Big Bang, like our planet. Scientists call them primary.
In our galaxy there is one black hole, which,according to astrophysicists, it was formed due to the gravitational collapse of supermassive objects. Scientists claim that such holes form the nuclei of many galaxies.
Astronomers of the United Statessuggest 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 galaxy M87, located 50 million light years from our planet, the black hole mass in the center of the galaxy M87 must be at least 6.5 billion solar masses. At the moment, it is considered that the weight of the largest black hole is 3 billion solar masses, that is, more than two times less.
Black hole synthesis
There is a theory that these objects can appear as a result of nuclear reactions. Scientists gave them the name of quantum black gifts. Their minimum diameter is 10-18 m, and the smallest mass - 10-5 in
Для синтеза микроскопических черных дыр был built the Large Hadron Collider. It was supposed that with its help it would be possible not only to synthesize a black hole, but also to simulate the Big Bang, which would allow 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.
