what are the three end stages of stars ?
Answers
1)stars having initial mass less than 8times the mass of the sun ultimately becomes white dwarfs .
2)star having initial mass between 8to 25 times the mass of sun ultimately becomes neutron star .
3) star having initial mass larger than 25 times the mass of the sun ultimately turn into black hole .
Answer:
There are three ways of evolution of stars depending on their initial mass.
1. End stages of stars having initial mass less than 8 times the mass of the Sun (Mstar < 8 MSun): Stars in this group undergo huge expansion and their radius increases by a factor of 100 to 200. In this stage they are called red giant stars. This name is given because of the large size and because of the fact that the stars look reddish due to their lower temperature. At the end of its evolution, these stars explode and their outer gas envelope is thrown out. The inner part contracts and its size becomes similar to the size of the earth. As the mass of the star is much higher than that of the earth and the size is similar to that of the earth, the density in the star becomes very high. In this state, the pressure due to the electrons in the star becomes independent of temperature and is able to balance the gravitational force forever. In this state, the star looks white and due to its small size it is called a white dwarf. After this its temperature keeps decreasing but its size and mass remain unchanged for ever and so white dwarf is the end stage of stars in this mass range.
2. End stages of stars having mass between 8 and 25 time the mass of the Sun (8 MSun < MStar < 25 MSun) : These stars also go through the red giant stage and later through the supergiant stage during which their size may increase 1000 times. The huge explosion, called the supernova explosion, which occurs at last is very powerful and so much energy is given off that we can see the star during the day also. The central portion which is left behind after the explosion, contracts and its size becomes as small as about 10 km. In this state, the stars are completely made up of neutrons and are called neutron stars. The pressure of these neutrons is independent of temperature and is capable of balancing the gravitational force forever. Neutron star is the end stage of these stars.
3. End stages of stars having mass larger than 25 times the mass of the Sun (Mstar > 25 MSun): These stars evolve like the stars in the second group but after the supernova explosion, no pressure is capable of balancing their huge gravitational force and they continue contracting forever. As their size becomes smaller, their density and their gravitational force increase tremendously. All nearby objects get attracted towards these stars and nothing can come out of them, not even light. Also, any light falling on these stars does not get reflected and gets absorbed inside the star. Thus, we cannot see the star at all but can probably see a minute black hole at its place. This end stage of the star is therefore called a black hole. Thus, we have seen that, depending on mass, there are three paths of evolution and three end stages of stars.