HOW BLACK HOLES ARE FORMED
Lets suppose a star like the Sun that is draining its nuclear fuel by transforming its hydrogen into helium and this one into carbon, oxygen and finally, iron arriving at a point in which the heat produced by the nuclear reactions is little in order to produce a dilation of the sun and thus to compensate the force of the gravity. Then the sun collapse, its density increases, this collapse just being braked only by the repulsion between the atomic electronic layer in the atoms. But if the mass of the Sun is high enough, this repulsion will be defeated (when exceeding the Chandrasekar limit) and could become to merge the protons and electrons in the atoms, forming neutrons and decreasing the volume of the star and so not remaining hardly any space between the atomic nuclei. The sun would become a neutrons sphere and therefore it would have a very high density. It would be what is denominated "neutrons star".
Naturally the neutrons stars are not formed so easily, since when the star collapse the gravitational energy become heat quickly causing a great explosion. It would be formed a nova or supernova expelling great part of their material, and thus the gravitational pressure would diminish in the explosion, and the collapse could stop. Thus it could became to what is denominated white dwarfs, when the distance between the atomic nuclei is diminished in a form that the electrons circulate freely in all the material, and it is the velocity of these electrons what impedes a greater collapse. Therefore the density is very high but not like in a neutrons star. But the speed of the electrons has a limit: the speed of light; and when the stellar balance demands a speed of the electrons greater than the speed of light, the collapse to neutrons is inevitable (the Chandrasekhar limit for this collapse is 1.44 solar masses).
It is calculated that above 2.5 solar masses, a neutron star would be collapsed even more, being fused its neutrons. This is possible because the Pauli's exclusion principle for which the strength of repulsion in neutrons have a limit when the speed of neutrons vibration reaches the speed of light.
This is the "TOV", the Tolman-Oppenheimer-Volkof limit, which is not clear because it is not yet known exactly the equations of state of the extremely dense matter.
Because we dont knows any force that would stop the collapse, this collapse would continue until convert the star in a point, creating a black hole. This is the way of how a black hole is formed. This punctual volume would imply an infinite density, for this reason the scientific community initially rejected this idea, but later S. Hawking proved that this singularity was compatible with the Einstein's general relativity theory.
Once the quantum pressure of degenerate neutrons was overcome, these neutrons could be merged into a point, but also is posible to exist a pressure of degenerate quarks and a new limit not yet calculated.
(© Angel Torregrosa Lillo)
[black holes index]
INTRODUCTION / HOW THE BLACK HOLES ARE FORMED / SPECIAL RELATIVITY AND BLACK HOLES / GENERAL RELATIVITY AND BLACK HOLES / BLACK HOLES DETECTION / The NON- PUNCTUAL BLACK HOLE / SPACE-TIME graphics on STAR COLLAPSE / HOLES In ETERNAL FORMACION, ETERNAL BLACK HOLES And OTHER MATHEMATICAL CONCEPTS
[prensa y libros][Cosmología][minigamesfree]