The life cycle of a star.

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Since childhood, we all love the song Twinkle Twinkle little stars. But how are these not so little stars are formed? If you want to know the answer then you are at the right place. If you are in a hurry, then you can go through the map below or you can read the full article for full details.

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 LET'S BEGIN!

HOW IS A STAR BORN?

Stars are born just like any other mammal. OK! I am sorry.

So, what actually leads to the formation of stars? A one word answer is DUST. Since you all are my curious fellows, I will surely give my 100% to explain it in the easiest way possible.

A star is formed from an extremely dense cloud of dust and gas and these clouds are called nebula. The dust particles move very slowly and when this happens, the gravitational force starts to dominate. 

The crab nebula

They come closer to each other and stick to each other. The temperature of the core becomes extremely high until it reaches several billion degrees Celsius which provide particles with excess of kinetic energy. Thus, they start to collide with each other vigorously.
 

BOOM! We have successfully created a BABY star. 

The life of a star totally depends upon its size from its birth.

A NORMAL DAY FOR ANY STAR.

The vigorous collisions cause a phenomenon, in the core, namely nuclear fusion.

Primarily, hydrogen atoms take part in nuclear fusion to form Helium atoms. This phenomenon produces a tremendous amount of energy and this energy comes counters the collapse due to gravity furthermore.

After millions or billions of years, when the stars will run out of hydrogen, they will start to fuse helium to form other heavier elements. The fusion of heavier elements produce a huge amount of energy that now it starts to dominate the gravitational collapse.

Thus the star will start to increase in size and form into a red giant.

This is the beginning of the end of stars. 

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Let us classify them as-

     Normal stars

·       Big stars

·       Extremely big stars

Let us see, how different sizes of stars have different stories to tell about their end.

NORMAL STARS.

These stars have the longest life span among all the other stars. Let see what happens next in their story.

RED DWARFS

Basically, there are stars, the Red Dwarfs, which are smaller than the sun, near to the size of Jupiter. They simply burn for their whole life and when they run out of the energy source, they form the White dwarfs.

There are also brown dwarfs, they have a very little hydrogen to fuse and they die very soon.

A red dwarf star

For now, you just understand that a White dwarf is a star’s corpse. They are extremely dense and are extremely hot. This is because; the heat is trapped inside them and has nowhere to go in the space. So, it will take many millions of years for them to cool down.

But what will happen to the stars like the Sun?!

YELLOW DWARFS

Well, even our Sun will one day form into a white dwarf, but it has another story to tell. Stars like our sun will form a red giant. 

Just a reminder for you all; when the Sun becomes a Red giant it will engulf earth in itself. There is no need to thank me for making you aware of this.

A yellow dwarf

Now, as the Sun will grow bigger, its outer surface will go farther away from its core. Gradually, this star will start to lose its material to outer space, since its gravitational force will be negligible. Slowly these materials will leave the star's surface and they will form something called planetary nebula.

A planetary nebula

But, that star’s core will be left all alone. A white dwarf.

But what happens with the white dwarf?

When the heat trapped in it will completely extinguish, then they will form into a black dwarf. Please note that they are not the Black holes. These black dwarfs will evaporate if and only if protons decay.

A white dwarf

BIG STARS.

When these stars run out of hydrogen atoms, they fuse much heavier elements and their size grow extremely big. 

Their energy source comes to an end when their core stars to fuse iron. At this time, the energy produced can no longer counter gravitational force. Therefore, it collapses under its own gravity and then explodes in a supernova. Its materials are now gone into the space, but even here we are left with the core, the neutron stars.

NEUTRON STARS

A neutron star

Neutron stars are incredibly dense objects. If you want to form a neutron star, then compress the mass of Mount Everest into a tiny sugar cube. They are so dense that the electrons and protons inside them fuse with neutrons and form a friction less fluid called Super fluid.

They feed on lighter bodies and eventually collapse to form a black hole. 

Death of a black hole 

EXTREMELY BIG STARS.

 

A black hole

They are extremely big stars. Their story is same as the big star, but here we do not meet any neutron star. Here we directly get a black hole after the supernova explosion.

Look around yourself, everything which you see is made up of the remnants of a star which died billions of years ago. Personally, I think that we should know more about them because they are trying to tell us something about our existence.