1. The Life Cycle of Stars Birth to death

2. Overview

3. Birth – part 1

4. Birth – part 2

5. Formation Formed in nebulae (clouds of gas) Gravity forms the gas into a globule Globule cools and condenses – IR and radio waves emitted (10000 to 1 million years) Heats up and rotates forming a disk - the protoplanetary disk.

6. Formation 2 Protostar – as material condenses, gets hotter and starts to glow ‘Brown dwarf’ stars formed if not enough material. After 50 million years, a newborn star may be formed At 15,000,000,000°C nuclear fusion can start.

7. Death - 1 The star in a stable state This stable stage lasts about 10 billion years Fusion process fails as hydrogen fuel is used up and star starts to die The death of star depends on its size.

8. Sun-like stars

9. Huge stars

10. The largest stars

11. Why do stars twinkle?