Star Formation (Oxford AQA IGCSE Combined Science Double Award)

Star Formation

• A star goes through a sequence of evolutionary stages, known as the life cycle of a star

• All stars follow the same initial stages:

  Nebula → protostar → main sequence star

Nebula

• Dust and gas (mainly hydrogen and helium) found in space experience gravitational attraction which pulls them together

• Smaller masses of dust are attracted by larger masses of dust to form a giant interstellar cloud of gas and dust, called a nebular

• All stars, including the Sun, began as a nebular

Nebula

Protostar

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

• As the particles are pulled closer together the density of the protostar will increase

• This results in more frequent collisions between the particles which causes the temperature to increase

• A protostar continues to get bigger as it attracts more particles

• This also causes its temperature to increase as kinetic energy is transferred from the impacting particles to the protostar.

Protostar