1 Birth of a Star Eagle Nebula Nebulae are large clouds of mainly hydrogen gas and dust material. Hydrogen is the most abundant element in the universe and so this gas forms the building block of each star. Gravitational forces between particles cause parts of the gas cloud to become very dense.

2 Protostar As the gas cloud collapses the hydrogen gas becomes even denser. The material pull itself into a disc and starts rotating. GPE —› KE Particle make more frequent collisions. The kinetic energy of the atoms gets converted to heat energy causing the centre to heat up. KE —› Heat A hot ball of gas forms at the centre called a Protostar.

3 Nuclear Fusion Begins Eventually temperatures as high as 15 million 0C are reached at the centre of the ball of gas. These high temperatures allow nuclear fusion reactions between hydrogen nuclei. When fusion begins the star gives out Electromagnetic radiation. The solar wind pushes away any material that has not formed into a planet.

4 Stable period of a Star = + The star settles into a long period of stability. Outwards pressure Inwards Gravity Balanced Forces Balanced forces act on the star. Inwards Pull of Gravity Outward Gas Pressure Outward EM Radiation Pressure = +

5 Summary of How a Star is Born