A star has a similar mass to the Sun. Astronomers model two stages in its evolution.
| Property | Earlier stage | Later stage |
|---|---|---|
| Fusion in the core | hydrogen fusion occurring | hydrogen fusion stopped; helium fusion occurring |
| Core radius | 1.0 × 108 m | 5.0 × 107 m |
| Outer radius | 7.0 × 108 m | approximately 100 times the earlier outer radius |
A planet orbits the star at a distance of 6.0 × 1010 m from the centre of the star. Assume that this distance remains constant while the star expands.
State the stage of evolution represented by the later stage.
Explain the changes in the core radius and the outer radius between the two stages.
Calculate the outer radius of the star at the later stage.
Compare the outer radius at the later stage with the orbital distance of the planet and state whether the surface of the star reaches the planet.
75 exam-style questions on Edexcel GCSE Physics 7.3 Stars, covering 7.3.1 Evolution of stars similar to the Sun, 7.3.2 Evolution of massive stars, and 7.3.3 Observing the Universe. Each one has a worked solution and a mark scheme showing where the marks go.