Explain how the life cycle of a massive star differs from the life cycle of a star similar in mass to the Sun, beginning from when each star leaves the main sequence.

WJEC A-Level Physics (Wales) — 6.3 Stellar evolution and cosmology (A-Level only) · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

A Sun‑like star leaves the main sequence by expanding into a red giant.
It then sheds its outer layers, creating a planetary nebula, and the core becomes a white dwarf.
A massive star also expands, but into a red supergiant.
It then explodes as a supernova.
The remnant is either a neutron star or, if massive enough, a black hole.

Examiner tips

  • Use the sequence red giant → planetary nebula → white dwarf for Sun‑like stars. Use red supergiant → supernova → neutron star/black hole for massive stars. Show clear contrast between the two paths.
  • Include the key terms: red giant, planetary nebula, white dwarf, red supergiant, supernova, neutron star, black hole.

Common mistakes

  • Confusing the order of stages (e.g. putting supernova before red supergiant). Using the wrong remnant for a Sun‑like star (e.g. neutron star instead of white dwarf).

Mark scheme (5 marks)

  1. A star similar to the Sun expands into a red giant (when it leaves the main sequence)
  2. The Sun-like star then sheds its outer layers to form a planetary nebula, leaving behind a white dwarf
  3. A massive star expands into a red supergiant (when it leaves the main sequence)
  4. The massive star then undergoes a supernova (explosion)
  5. The remnant of the massive star forms either a neutron star or a black hole (depending on mass)

Key terms in this question

main sequence

Related

More Stellar evolution and cosmology (A-Level only) questions

▶ Try answering this question with AI marking (free) →