Life Cycle of a Star (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award)): Revision Note

Life cycle of a star

Small mass star

• A small mass star is one which has a similar mass as the Sun

• After the stable star stage, a small mass star finishes its life cycle in the following evolutionary stages:

red giant → planetary nebula + white dwarf

• Red giant:

  • Formed when a small mass star reaches the end of its life 

  • The outer layers of the star expand and cool

• Planetary nebula:

  • Formed when the outer layers of the star are pushed away

• White dwarf:

  • Formed when the core of the star collapses

  • Found at the centre of a planetary nebula

The life cycle of a small mass star

The life cycle of a star that is similar to our Sun

Large mass star

• A large mass star is one with a larger mass than the Sun

• After the stable star stage, a large mass star finishes its life cycle in the following evolutionary stages:

red supergiant → supernova → neutron star

• Red supergiant:

  • Formed when a large (or very large) mass star reaches the end of its life 

  • The outer layers of the star expand and cool

• Supernova:

  • An exploding red supergiant

• Neutron star:

  • Formed when the core of a large star collapses

  • Very dense, but not as much as a black hole

Very large mass star

• A very large mass star is one with a much larger mass than the Sun

• After the stable star stage, a very large mass star finishes its life cycle in the following evolutionary stages:

red supergiant → supernova → black hole

• Black hole:

  • Formed when the core of a very large star collapses

  • Extremely dense

The life cycle of a large mass star

The life cycle of a star much larger than our Sun

Formation of new stars and planets

Extended tier only

• The nebula from a supernova may form new stars with orbiting planets

  • The heaviest elements (elements heavier than iron) are formed during a supernova and are ejected into space

  • These nebulae may form new planetary systems

A supernova

The nebula formed from a supernova may eventually form new stars with orbiting planets