When we look up at the night sky we see it filled with tiny luminous points that have captured our attention for millennia. These points, as we all know, are stars and they are the reason we exist.

You see, stars are the cosmic factories that produce almost all the elements in existence, even the ones that are necessary to create life as we know it. So, essentially, we are all made of star dust.

In a sense, we are a way for the universe to know itself. Pretty profound, right? But even something as beautiful as a star has to come to an end. Just like everything else, stars are born, and ultimately die out.

But the end cycle of a star's life is truly a remarkable event, especially the big ones. The fate of the stars actually depends on the mass of the stars and it could go out in one of the following ways.

White Dwarfs

Stars are basically hot balls of gases, mostly hydrogen and helium. At the core they fuse hydrogen into helium atoms in a process called nuclear fusion which releases a lot of energy. That is how we experience the heat of the sun even from such a vast distance away.

When stars, that have less than half of the mass of our sun, run out of hydrogen, they begin to slowly cool down as they are not able to fuse helium atoms into heavier ones. So, they begin to shrink into an incredibly dense object called a white dwarf, which is comparable to Earth in volume and Sun in mass.

Stars, that have more than half of the mass of our sun and upto 4 times the mass of our sun, also end up as white dwarfs but before that, they become red giants. Since they are bigger, they can even continue to fuse helium to form carbon and oxygen, but cannot go beyond that.

The fusion of helium atoms gives out a lot of energy, that causes the outer layers to expand into a red giant. This marks the beginning of the end for such stars. Ultimately the outer layers of the star drift away in a nebula and all that is left behind is a white dwarf of carbon and oxygen.

Neutron Star

Image Credits: NASA

There are many stars that are much more massive than our sun. These massive stars ultimately end up as neutron stars. Since they have a much larger mass than the lesser massive stars, they can fuse together carbon and oxygen atoms at the core at the end of their cycle, and in fact, keep on going beyong that.

This fusion continues until the production of iron starts at the core. After that, the star can no longer support its own mass and so collapses in on itself. This causes one of the most violent explosions in the universe, known as a supernova.

A supernova explosion is a rare event in a galaxy and can be so bright that it can outshine all the stars in the galaxy for a brief amount of time. A supernova explosion is also responsible for creating even heavier elements than iron which are scattered throughout the cosmos making life form like us possible.

What is left at the core ultimately, is a neutron star which is the smallest and densest star in the universe, having a mass of around 10 kilometres with a mass of 1.4 to 2 times the mass of our sun.

Black Holes

Much more massive stars finally end up as black holes. The gravity at the core of these stars, during the final period, is so strong that it becomes a black hole.

As we know, black holes are so dense and have such a powerful gravitational pull, that not even light can escape it. What happens to the core of such stars when a black hole is formed, is currently unknown.