# A student states: 'All stars go through exactly the same stages in their life cycle.' Explain why this statement is not fully correct, referring to the stages that follow the main sequence for stars of different sizes.

> OCR GCSE Physics A: Gateway Science (J249) — P6.3 Astronomy · Explain · 4 marks

> Stars spend most of their lifetime in the main sequence stage, during which gravitational forces and outward pressure are balanced. However, what happens after this stage depends on the mass of the star.

## Mark scheme (4 marks)

1. In the main sequence, gravitational forces and outward pressure are balanced (accept: stars are stable during the main sequence)
2. When hydrogen is used up, a star similar in size to the Sun expands to form a red giant
3. A massive star (much larger than the Sun) explodes as a supernova after the main sequence (accept: after the red supergiant stage)
4. After a supernova, a massive star can form a neutron star or black hole, whereas a Sun-like star ends as a white dwarf (accept either contrast stated clearly)

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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