Finally we reach the most spectacular part of a star’s life: its end!
So what happens? Well, it depends on the size of the star we are talking about. Stars that are the size of our sun and smaller will end up as white dwarfs, which we can imagine as hot cinders cooling off in space. Massive stars, those ten times bigger than our sun, will have a very beautiful and amazing ending: the Supernova!
When our sun will consume all the fuel (hydrogen) in its core, it will start to collapse. This will occur due to the lack of outward pressure to balance the inward gravitational pull. This process will increase the temperature in the core and hence speed up the nuclear reaction inside. The sun will blow up like a giant balloon—a balloon so big that it will swallow up Mercury and Venus, and cause all the oceans on Earth to evaporate. At this point the sun will be known as the “Red Giant”. This stage won’t last long and the sun will again collapse even further, to the size of our Earth. Now the matter inside the sun will be so tightly packed that nothing more can happen to it and the sun will stabilize.
An extremely hot star which is not generating energy is called a “White Dwarf”. Ask an adult to burn a piece of coal until it is glowing hot. Now put out the flames and watch it cool off. As the coal cools off, a thin, white powder-like substance will set on the coal’s surface. This white powder is nothing more than carbon. Underneath the powder, the coal will be glowing hot.
The white dwarf behaves the same way. The white carbon and the relatively tiny size of the star give it the name “White Dwarf”.
Science Smart: Which star will use up its fuel faster? Our sun or a star ten times more massive than our sun?