Stars are big balls of gas mostly are made of hydrogen and helium and it can be of different color, size, temperature, luminosity. Stars come from a big cloud called stellar nebula, stars live a long time and then died in a big explosion called supernova.
2)Types of stars
The different types of stars are supergiants, red giants, main sequence and white dwarf stars.
-supergiants are the most huge stars in the universe and their color are red, they are mostly cold and they are bright.
Red giant are large stars and also have a red color this stars are cold and bright.
-Main sequence are usually medium size stars, the color of this stars are usually withe yellow and yellow.
A big group of stars that forms a narrow band from the upper left to the lower right, according to luminosity and the temperature on the H-R diagram.
-White dwarfs are young stars and have a smallest size, this kind of stars are usually dim but this stars are really hot and this stars have a white color.
3) H-R Diagram
H-R Diagram is a instrument that the astronomers use to classify the stars dependent their characteristics such as luminosity, color, spectral type, color, temperature,and the age of the stars, that's how we now how bright or dim, how hot or cold, how big or small a star is, also help to know the color of the stars and how old a star can be.
4) NUCLEAR FUSION
Nuclear fusion is a process of the nuclear reactions inside a star, which change two hydrogen gas molecules into a helium molecules, this is how the stars make energy by this process called nuclear fusion.
5) THE CYCLE OF A STAR
Is the process of the star starting when they born until they died and another stars born this cycle can take millions or billions of years until ends. Stars born from a huge cloud called stellar nebula, There is three kinds of stars that have a different cycle of life and this stars are:
-The sun like a star who born from the stellar nebula becoming stars like the sun and then becoming a red super giant star and then becoming a planetary nebula after this the star become a white dwarf and for end it becomes a black dwarf.
-Huge stars born from a big cloud called stellar nebula becoming a huge star after this this star become a red super giant star and then explode in a big explosion called supernova after this the star collapse again and become a neutron star.
-Giant star born also from the big cloud called stellar nebula and become a giant stars after this the star become a red giant and died in a big explosion called supernova after this the star become a black hole
