LIFE CYCLE AND DEATH OF A STAR

In my previous blog, I have written about the birth of a star. So if you guys are reading this blog then you should read that blog first for better understanding.

Link – BIRTH OF A STAR

In the last blog, we have learnt how star take birth and where? Now we have to understand about the life cycle and death of a star.

Let’s begin

When a star is born, some star has more mass compared to our sun and some star has a lot more mass. So lets divided into three parts – Low mass star, Average or medium mass star and massive or higher mass star.

Stars death depend on their mass. The more mass a star has, the more material it has. But due to the gravitational force of star with higher mass, its core temprature is higher. So the material of that star burns quickly and they die quickly compared to low mass star.
A star with a low mass dies differently and a star with a higher mass dies differently.

Low mass star –


Stars which are (0.08 to 8) times more massive than our sun, they are considered low mass stars. When these low-mass stars fuse their entire material, then nuclear fusion stops in them. Due to this, the force due to the nuclear energy of the star which is facing outwards and the gravitational force which is facing inwards cannot keep balance and Star leaves up to 50% of its mass in space as Planetary Nabula and survives only the bright core of the shape of the earth which is called as white dwarf. These white dwarf end after glowing for thousands of years. Now the ball that remains as its residue is called black dwarf. Although the white dwarf is much smaller than the burning star. But still their mass is quite large. Their mass can also be equal to at least 1.4 solar mass. White dwarf is as big as our earth. So How can you find this star in the night sky? We can see this white dwarf with the help of telescope. As we know, the brightest star in the night sky is Sirius and the sirius also has a white dwarf which we know as sirius B.

Average or medium mass star –


Stars which are (8 to 20) times more massive than our sun, they are considered average or medium mass star. After the nuclear fusion is over, When the star of the average mass is over 1.4 times the mass of the sun, the electron and the proton inside its core react together to form the core of the neutron. Now the supernova explosion outside the core leaves only a very dense circle of neutron (almost 25 km in diameter) which is called as neutron star (mass = almost 3 times of our sun). The gravitational force of these stars is very high. The gravitational force of these stars is 2,000,000,000,000 times more than Earth. According to law of conservation of angular momentum, these stars spin very fast. Due to such fast rotation, these stars form a very strong magnetic field. These stars constantly emit radiations, due to which they seem to be blinking from the earth. Their energy dissipates after many years and this star becomes just the normal neutron star. Astronomer DR FRITZ ZWICKY & WALTER BAADE first told about the origin of neutron star after supernova. The neutron star was first discovered in 1932. The name of the nearest neutron star of our Earth is calvera. It is located in the ursa minor constellation. It can be at least 250 – 1000 light years away from us.

Massive or higher mass star –


Stars which are (over 20 ) times more massive than our sun, they are considered massive or higher mass star. Like a star with medium mass, supernova explosion also occurs in a star with higher mass and their core collapses to form black holes and their whole mass is absorbed in singularity and time does not exist here. According to the theory of einstein’s theory of relativity, an observer standing at the target range away from the black hole will have a very slow time and the time there will be very slow. That is, the time that is going on earth will be faster or less than anywhere in the Universe.
There are many types of black holes present in the universe and every black hole have their own property.


• Stellar mass black hole


• Super massive black hole

• primordial or small black hole

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