The life of a star. 5th grades.

Recently, at class, many of you asked me about stars. How are they born? How do they produce energy? How do they die? In this report I will try to answer all these questions shortly:

1.- How are they born?

The birth of a star is something very mysterious. It happens inside a giant nebulae. A nebulae is a great mass of hydrogen. In accordance with scientists and astronomers, in the birth of a star the hydrogen atoms begin to stick together, becoming into a bigger and bigger ball. Finally, when the ball is big enough, there is an ignition: the mass of hydrogen, due gravity forces, starts a fusion process. Thus, the star is just born.

2.- How do stars produce energy?

As said before, a star is born just when gravity heats the hydrogen, initializing a fusion process. And what is a fusion process? Well, fusion is a type of nuclear energy. It takes place when two similar atoms stick together, becoming a different one. In a star, the fusion is based on hydrogen: two hydrogen atoms become into one helium atom. During this process a great amount of energy is released. Energy that we perceive in form of light, heat and other type of radiation.

3.- How does a start die?

The amount of hydrogen which a star has is finite. So, when this hydrogen is over, theoretically the start should die, like a candle. But instead of this, the star becomes stubborn. "Don't I have hydrogen? Let's fusionate helium". And the helium fusion begins. However, this type of fusion is not as efficient as hydrogen. So in the process the star makes up for it by growing. Then the helium also runs out. But the stubborn start refuses to stop, fusionating now Beryllium. Then, Carbon; then, Magnesium. Meanwhile, the growing process continues. At one point the star cannot grow any more. Now only two things can happen:

a) If the star is very big, it collapses, and then bursts in a huge explosion (a supernova). 

b) If the start is medium size (like our Sun), the growing process ends in the releasing of hot matter.

In both cases the only remaining thing is the core of the star. If the star is big, the core is a neutron star. If the star is medium size, or small, the remaining thing is a white dwarf star.

In the following video, a recreation of the end of our Sun. Do not worry; in accordance with scientist, this will not happen tomorrow. At least, 5.000.000.000 years remaining.