What does Edexcel GCSE Astronomy Topic 14 cover?

Topic 14 covers the balance between radiation pressure and gravity in a main sequence star, the changes to that balance through the life cycles of low-mass and high-mass stars, the stages and timescales of each route, the electron pressure supporting a white dwarf and the neutron pressure supporting a neutron star, the Chandrasekhar Limit, and how astronomers find evidence for black holes.

How does a star like the Sun end its life?

A star like the Sun ends gently: from a nebula it becomes a main sequence star, then a red giant when its core hydrogen runs out, then it sheds its outer layers as a planetary nebula, leaving a hot, dense white dwarf supported by electron degeneracy pressure, which slowly cools to a black dwarf. There is no supernova.

How does a high-mass star end its life?

A high-mass star ends violently: from a nebula it becomes a massive main sequence star, then a red supergiant, then explodes as a supernova. What remains is a very dense neutron star (supported by neutron degeneracy pressure) or, if the core is massive enough, a black hole.

What is the Chandrasekhar Limit?

The Chandrasekhar Limit is the maximum mass (about 1.4 times the Sun's mass) that electron degeneracy pressure can support. A stellar core below this limit can end as a white dwarf; a core above it collapses further into a neutron star or a black hole, so the limit decides the final remnant.

How should I revise Topic 14 for Edexcel GCSE Astronomy?

Learn the radiation pressure versus gravity balance for the main sequence, and the two life-cycle routes by mass (planetary nebula and white dwarf for low-mass; supernova and neutron star or black hole for high-mass). Know the degeneracy pressures, the Chandrasekhar Limit, and how black holes are found (gravity and X-rays). Match the route to the star's mass.

EnglandAstronomy

Edexcel GCSE Astronomy Topic 14 Stellar evolution: a complete overview of the life cycles of low-mass and high-mass stars and their remnants

A deep-dive Edexcel GCSE Astronomy guide to Topic 14 Stellar evolution. Covers the radiation pressure versus gravity balance, the life cycles of low-mass and high-mass stars, the degeneracy pressures supporting white dwarfs and neutron stars, the Chandrasekhar Limit, and detecting black holes, with the exam patterns Pearson repeats.

Generated by Claude Opus 4.812 min read1AS0 Topic 14Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

Jump to a section

What Topic 14 actually demands
The low-mass route
The high-mass route and remnants
How Topic 14 is examined
Check your knowledge

What Topic 14 actually demands

Stellar evolution covers how stars live and die by mass. It rewards the ordered stages of each route and clear explanation of the forces that support stars at each stage. It links closely to the HR diagram (Topic 13) and the Sun (Topic 10).

This guide walks through the dot points, then sets out the exam patterns Pearson repeats. Each dot point has a matching page with practice questions; this overview ties them together.

The low-mass route

A main sequence star is stable because radiation pressure from fusion balances gravity. A star like the Sun evolves: nebula to main sequence to red giant to planetary nebula to white dwarf (held up by electron degeneracy pressure) to black dwarf. The ending is gentle: a planetary nebula and a white dwarf, not a supernova.

The high-mass route and remnants

A high-mass star evolves: nebula to main sequence to red supergiant to supernova to a neutron star (held up by neutron degeneracy pressure) or a black hole. The Chandrasekhar Limit (about 1.4 solar masses) is the most mass electron pressure can support, deciding the remnant. Black holes emit no light, so they are found by their gravity on companions and X-rays from infalling gas.

How Topic 14 is examined

A typical Edexcel profile for stellar evolution:

Description. The ordered stages of each route, matched to the star's mass.
Explanation. The radiation pressure versus gravity balance and the degeneracy pressures.
Recall. The Chandrasekhar Limit and how black holes are detected.
Links. The HR diagram positions through a star's life.

Check your knowledge

A mix of description and explanation questions covering Topic 14. Attempt them under timed conditions, then check against the solutions.

State what balances gravity in a main sequence star. (1 mark)
Describe the stages of a star like the Sun from main sequence to its final state. (3 marks)
State what supports a white dwarf against gravity. (1 mark)
Describe the stages of a high-mass star from red supergiant to its final state. (2 marks)
State what supports a neutron star against gravity. (1 mark)
State what the Chandrasekhar Limit determines. (1 mark)
State one way astronomers find evidence for a black hole. (1 mark)

Sources & how we know this

Pearson Edexcel Level 1/Level 2 GCSE (9-1) in Astronomy (1AS0) specification — Pearson (2017)