# Describe the stages in the life cycle of a star that has a similar mass to the Sun, beginning from a nebula and ending as a white dwarf.

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

## Mark scheme (4 marks)

1. A nebula is a cloud of dust and gas that is pulled together by gravity / gravitational attraction
2. The collapsing cloud forms a protostar, where temperature and pressure become high enough for nuclear fusion of hydrogen to begin
3. The star becomes a main sequence star, where the inward gravitational force is balanced by the outward pressure from nuclear fusion
4. When hydrogen is used up, the star expands to form a red giant, then contracts under gravity and cools to form a white dwarf

## Key terms

- [nebula](https://www.gradenine.co.uk/glossary/nebula)
- [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 "Describe" 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/describe-the-stages-in-the-life-b3ddf81b) · Published by Druglandscape Ltd.