The Life Cycle of a Star

Describe the start of a star up to the main sequence

1. A cloud of dust and gas called a nebula is pulled together by gravity

2. As the density rises, the temperature increases and fusion of hydrogen nuclei to form helium nuclei start, causing the star to become a protostar

3. In the main sequence stage, the outward force of nuclear fusion expanding the star is in equilibrium with the inward force of gravity

Describe the red giant stage to the end for a small/medium star

1. As hydrogen begins to run out, helium nuclei fuse to make heavier elements up to iron

2. The star then expands and becomes a red giant

3. It then ejects its outer layer of dust, leaving a hot core called a white dwarf

4. It runs out of energy and becomes a black dwarf

Describe the end of a bigger star

1. As hydrogen begins to run out, helium nuclei fuse to make heavier elements up to iron

2. The star then expands and becomes a red super giant

3. It undergoes more fusion, expanding and contracting several times

4. The star then collapses and explodes in a supernova, creating elements heavier than iron and distributing them throughout the universe

5. The remaining solid core is a neutron star or becomes a black hole if the star was large enough

Which property of a star does the range of wavelengths emitted depend on?

Temperature