By: Gonzalo Herrero, Donato Fuejo , Celso Galvan

In space, gas and dust gather one another because of the collision of its particles and a chemical reaction takes place. This occurs along millions of years and it foms a huge dust cloud.

Inside of it there are the “Creation Pillars” where new stars are formed.

They are seven thousand light year far way of the Earth. They are formed of interstellar gas and they are few light years wide and they have enough density to allow stars to be create.Stars are formed at the bottom of the pillars and while they are getting bigger they rise until the top of the pillars

A process of concentration starts and protostars are formed. These protostars much bigger than our solar system and they are relatively cold. You can only see them using the infrared spectrum .

While the process of concentration the protostargets smaller.When it reduces its size it starts burning because thefusion reactions that transforms the hydrogenInto helium start

The star was born, is generating light by internal nuclear reactions converting hydrogen to helium. Hydrogen accumulated on the nucleus is limited. More mass of the star means more pressure on the nucleus, more temperature and more internal nuclear reactions. The higher the temperature, the more numbers of nuclear reactions and less time of life because the hydrogen runs out.

They are three principals types of stars: Blue stars- it´s big, very hot and very young.

Blue stars live shortly. Yellow stars- it´s warm, has a longer life,

about ten billions years, are mediu sized and are very common.

Red stars- small and cold, can have such long lives as the age of the universe.

At the stage of evolution of the stars are extremely stable, it´s surface temperature does not change, it´s diameter is constant and that is when they can have planets around and can developed live on these planets.

When the energy of the stars run out (its life depends on how was its amount of mass) its death relies on, again, how big the star was.A star can end in two different ways: the light ones consume themselves and became dwarf white stars and the big ones formed what it is called a supernova, an enormous explosion.

When the light stars are near to their end, progressively they rise their size until the reaches a size a hundred times bigger than they was at the beginning (they are called Red Giants).

The red giants suddenly start to shrink until they get a size that it is much slower than the size they had before becoming a red giant.

This is because they had run out all of its nuclear fuel and they get colder (meanwhile his light also disappears).

• Depending of the amount of mass the star had it could turns into a neutron star or a dark hole. I’m going to take the Sun as a reference to determine the quantity of mass.

• All heavy stars when their nuclear fuel runs out, don’t have any inner pressure that can hold the gravitational attraction. This provoke that in the inside, protons and electrons begin to fusion themselves and neutrons were formed so huge amounts of energy are spread out.

Because of the energy spread, the outer parts of the stars explode to the space while the nucleus it collapsing. This is known as a supernova

The outer parts spelled formed nebulas and from now on two different things can happen:

1. If the star was between six and thirty times the Sun, the collapsed can stabilize, but, because there’s no other thing that neutrons in the nucleus it becomes what is known as a neutron star. (they turn very very quickly).

2. But, if the stars was more than thirty times the Sun, the nucleus collapse more than the neutron stars and becomes a dark hole (a limited space where there’s so high density than even the light can’t scape)

Supernova

Neutron Star Dark Hole