Stars: Nuclear Furnaces

Elemental Composition of Universe

Elemental Composition of Human Body

oxygen

carbon

hydrogen

nitrogen

calcium

Nuclear Fusion on Earth2H + 3H 4He + n + Energy

A Star is Born

Inside a Star

Inside a Star’s Core

Net Result: Fusion of Hydrogen to Helium

• 2H + 2H 4He + Energy

Production of Carbon:The Triple Alpha Process

The Carbon Fusion Cycle:Production of Nitrogen and Oxygen

Formation of Heavier Elements

• Fusion in star cores produces all elements up to Iron

• Supernova explosions produce all elements heavier than Iron

Scattering the Seeds of Life