# A star of similar mass to the Sun is currently a stable main sequence star. Explain what happens to this star from the point at which it runs out of hydrogen fuel, ending with the formation of a white dwarf.

> Pearson Edexcel International GCSE Physics (4PH1) — 8.2 Stellar evolution · Explain · 4 marks

## Mark scheme (4 marks)

1. When hydrogen is used up, nuclear fusion (producing outward pressure) stops / decreases, so the star collapses under its own gravitational attraction / inward gravitational force exceeds outward pressure
2. The star expands massively to become a red giant
3. Fusion reactions in the red giant eventually come to an end / hydrogen/fuel is exhausted in the red giant
4. The star then contracts / collapses under gravity and cools to form a white dwarf

## Key terms

- [main sequence star](https://www.gradenine.co.uk/glossary/main-sequence-star)
- [white dwarf](https://www.gradenine.co.uk/glossary/white-dwarf)

## Related

- [Revision notes for Pearson Edexcel International GCSE Physics (4PH1)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-star-of-similar-mass-to-1e692d1e) · Published by Druglandscape Ltd.