Star Formation (Cambridge (CIE) IGCSE Combined Science): Revision Note

Star formation

• Stars go through a sequence of evolutionary stages, known as the life cycle of a star

• All stars follow the same initial stages:

nebula → protostar → stable star

Nebula

• Stars form from a giant interstellar cloud of gas and dust called a nebula

Protostar

• The gravitational attraction within a nebula pulls the particles closer together until a hot ball of gas forms, known as a protostar 

Stable star

• Once the protostar becomes hot enough and the forces inside the star become balanced, it is known as a stable star

Fate of the star

• Once a stable star is formed, the final stages of its life cycle depend on its mass

• The different life cycles are shown below

Summary of the life cycles of stars

Flow diagram showing the life cycle of a star which is the same size as the Sun (solar mass) and the lifecycle of a star which is much more massive than the Sun