Black Hole
A black hole is an object with such a strong gravitational field that even light cannot escape from its surface. A black hole may be formed when a massive object (very big object) undergoes uncontrolled contraction (collapse) because of the inward pull of its own gravity.
It is black because it has a strong gravitational field in which light cannot escape from its surface or even any light pass on its surface. A black hole in galaxy comes into the view when a star completes its entire life and dies that means when the star uses all its energy and lastly converts into a black hole with a strong gravitational pull.
The neutron stars shrink so much and become so dense that the resulting black holes do not allow any light to escape from its surface. This is because the black holes have a tremendous gravitational force. Since even light cannot escape from its surface, therefore, black holes are invisible so that they cannot be seen with naked eyes. The presence of a black hole can be felt only by the effect of its gravitational field on its neighboring objects in the sky.
A black hole in the galaxy is a place having the strongest gravitational pull which does not even allow light to pass through it. A black hole in galaxy appears when a star completes its life and dies, i.e. when the star consumes all its energy and finally turns into a black hole with a strong gravitational pull.
A black hole cannot be seen by the naked eyes, but with the use of a telescope with specialized techniques, a black hole can be and has been observed by the scientists. The theory of relativity or general relativity is given by Albert Einstein in 1915 explains the gravitational pull in the galaxy forming a black hole.
The astrophysical implication signifies that the space in the galaxy where time and space are deformed, giving no space for the light to escape. In other words, it can be termed as the end of the life a massive star.
The idea was first published in the paper by John Michell in 1783. He concluded that the formation of such a body would come into existence when the surface escape velocity will be more than the speed of the light. He also said that such a body would form when the diameter of a star will exceed that of the sun’s diameter.
The validity of the black hole was supported by many scientists, including John Michell, Albert Einstein, S. Chandrashekar, Karl Schwarzschild and others. The Indian scientist presented his theory of Chandrashekhar limit in regard to the black holes. The Chandrashekhar limit is the mass of the white dwarf. The value of the limit is equal to 1.4 solar mass (2.765 × 1030 kg).
The following are the stages, explaining how a star dies and converts into a black hole:
Nebula: A nebula is a combination of hydrogen gas and dust particles present in the space. There are different types of Nebula in the space. A nebula is considered as the birthplace of a star. The nebulas present in the space are Emission Nebula, Reflection Nebula, Planetary Nebula, and Dark Nebula.
Star: A star is a sparking mass formed by the nuclear fusion of hydrogen and helium gas. The fusion reaction generates energy giving it a luminous appearance. The color of a star varies from red to blue-white.
Red Giant: A Red Giant is formed when a star loses its hydrogen available at the center of the star. It is a star with cool surface and bright light. These are large stars also called as Super Giants.
Red Dwarf: These are small stars with a low temperature. Their life span is about 100 million years. Examples of Red Dwarf are Proxima Centauri and Barnard's Star.
White Dwarf: A tiny star having a high temperature. The mass of white dwarf is equal to the mass of the Sun. White Dwarf is the last stage in the life cycle of a star. The nuclear energy of the star is completely consumed by the star converting into a shrunk star.
Super Nova: Death of a star with an explosion. There are two types of a star: in type one, the light of the white dwarf falls on the Super Nova causing an explosion and in the type two, the nuclear energy is completely used which results into an explosion.
Neutron star: when a Super Nova explodes, a neutron star comes into formation. A neutron star, as the name suggests have neutron in it. The explosion combines the protons and electrons of the star resulting into a neutron star.
Black Hole: A black hole is formed with the end of the life a massive star. The density cannot be calculated, but it is assumed that the density of a black hole is more than that of Sun. it is believed that a black hole deforms the shape of the space.
The gravitational pull of the black hole captures the star and other planetary bodies near the black hole. A black hole is named as a black hole because light cannot pass through it which makes the color of the hole as black.
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