Everything on the GCSE Physics The Life Cycle of Stars poster is written out below, section by section. Use it to search the sheet, copy parts into your own notes, or check a fact quickly.
Key Idea
A star's future is determined by its mass.
- Small or medium stars end as white dwarfs that cool into black dwarfs.
- Massive stars end in spectacular explosions, leaving neutron stars or black holes.
Formation
Dust and gas
Stars form in a nebula – a giant cloud of dust and gas in space.
Protostar
Gravity pulls the material together. The cloud heats up and forms a protostar.
Main sequence star
Nuclear fusion begins in the core, turning hydrogen into helium and releasing energy. The star is stable and shines for millions to billions of years.
Small and Medium Stars
Red giant
When hydrogen runs out in the core, the star expands and cools. Fusion continues in a shell around the core.
White dwarf
The outer layers are lost, leaving a hot, dense core.
Black dwarf
Over billions of years, the white dwarf cools and fades (not yet observed – the Universe is not old enough).
Massive Stars
Red supergiant
Massive stars expand into red supergiants as hydrogen runs out. Fusion continues in heavier elements.
Supernova
The core collapses and the star explodes, blasting material into space and creating heavy elements.
Neutron star
If the remaining core is dense enough, it becomes a neutron star.
Black hole
If the core is even more massive, it collapses into a black hole.