Our Sun is an average star in the Universe. Each star has a life cycle and all the stars evolve with time.
Stars are generating enormous amounts of energy by the fusion reactions taking place at their core. Once the material needed for fusion gets exhausted at the center, the star becomes unstable and explodes. This is called a NOVA or a SUPERNOVA depending on the intensity of the explosion.
Whether a star turns into a Nova or a Supernova depends on the mass of the star. The Indian Nobel laureate Subramanian Chandrasekhar has postulated that for a star to turn into a Supernova it has to have a mass that is more than 1.4 times that of our Sun. This is known as the “Chandrasekhar’s Limit”.
This was later modified by the Tolman-Oppenheimer-Volkoff limit to over 3 times the Sun's mass.
Black holes are formed by stars with masses that are 10 to 15 times more massive than the Sun. When the star totally burns itself out slowly the gravitational forces take over and it starts contracting and finally implodes on itself. This finally collapses to what is known as singularity which has zero volume and infinite density. At this point, the gravitational attraction is so strong that even light cannot escape from it. As light cannot come out of it we cannot see a Black hole.
When a Black hole passes through interstellar matter that is present all over the Universe, it starts attracting the matter towards it. As that matter nears the Black hole it moves faster and faster and this heats it up to a point where the matter starts emitting X rays. We can identify a Black hole by these x ray emissions.
No comments:
Post a Comment