# A star much more massive than the Sun eventually runs out of hydrogen fuel. Explain the sequence of events that follows, from the point at which hydrogen fusion ends, until a final compact object remains.

> Edexcel A-Level Physics (9PH0) — 7.1 Electric fields · Explain · 5 marks

## Mark scheme (5 marks)

1. When hydrogen fusion ends, the outward pressure can no longer balance gravity, so the star begins to collapse (gravitational collapse).
2. The collapse increases the core temperature and pressure, allowing heavier nuclei to fuse (fusion of elements heavier than hydrogen/helium occurs).
3. Once all fusion reactions are complete, the star is too massive to remain stable and collapses violently, then rebounds to produce a supernova explosion.
4. The supernova distributes the elements created by fusion reactions throughout the universe.
5. What remains after the supernova is either a neutron star or a black hole.

## Key terms

- [fusion](https://www.gradenine.co.uk/glossary/fusion)

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-star-much-more-massive-than-d73e4aa2) · Published by Druglandscape Ltd.