1. Life cycle of stars
Nebulae to supernova

2. Stars and radiation
Stars are huge nuclear reactors that give off different forms of radiation (see below) all of which can be detected by specialist telescopes.
Visible Light
Ultra violet
Infra red
Gamma rays
X-rays
Radio waves

3. A star is born
Gas and dust particles in space collect in dense ‘clouds’ called nebulae. Gravity causes the gas and dust to collapse in on itself.
Surrounding gases are drawn in by the increasing mass of the huge swirling Hydrogen gas cloud (called a protostar). As the mass and gravity of the protostar increases, it begins to spin and heat up.

4. Nebula – cloud of gas & dust

5. The ‘horse head’ nebula

6. Birth of stars continued
The increasing pressure causes temperature to rise as particles are squeezed together (eg bicycle pump). Finally when the temperature and pressure become great enough Nuclear fusion begins and the new star bursts into life releasing light and heat.
Temp required for nuclear fusion = 17 million 0C

7. Nuclear fusion
Nuclear fusion is the process by which the nuclei of atoms collide together at great speed and extreme temperature causing them to fuse together, releasing huge amounts of energy in the form of light, heat, and radiation
E.g. H1 + H He2

8. Our sun

9. Sunspots
Dark spots on the surface of a star indicate slightly cooler areas on the surface.

10. Life of a star
Stars will continue to burn their Hydrogen and Helium fuel source while it remains. The longevity of the star is determined by its size (amount of gaseous fuel) and the rate at which it burns this fuel.
Our sun is a small – medium sized star and will last 10 billion years before it runs out of fuel. Larger stars don’t necessarily live longer – they burn their fuel faster.

11. Death of a star
Stars turn Hydrogen into Helium during nuclear fusion reactions. The Helium collects at the core of the star. Eventually the Hydrogen outer shell runs out and the Helium inner shell starts to expand forming a GIANT star (colour depends on size / temperature) 200 – 300 times its normal size.
Our sun will consume the 4 inner planets of the solar system, including Earth, when this occurs.

12. Red Giant

13. Red Giant

14. Death throes of a star
Eventually the outer layers are thrown off into space (Nova) and the remaining core of the star collapses under weight of gravity leaving behind a very dense inner core glowing brightly with remnant heat called a White Dwarf (typically the size of Jupiter).
Very large stars have a more violent end blowing matter and energy into space in an explosion called a Supernova. Heavy elements like iron and lead are formed during supernova
The biggest stars are thought to collapse under their own massive gravity following the supernova event forming extremely dense neutron stars (pulsars) or Black holes.

15. White Dwarf

16. A Supernova

17. Black holes

18. Black hole

19. The fate of different sized stars

20. Stars life cycle