Star Formation (Oxford AQA IGCSE Combined Science Double Award)

Revision Note

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

Nebula, IGCSE & GCSE Physics revision notes
A nebula is a cloud of gas and dust in space (Image courtesy of NASA)

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

Protostar, IGCSE & GCSE Physics Revision Notes
The nebula collapses due to gravity and begins to rotate to form a protostar (Image courtesy of NASA)

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