Explain how the life cycle of a star much more massive than the Sun differs from that of a star similar in mass to the Sun. In your answer, refer to the stages after the main sequence.

AQA A-Level Physics (7408) — 3.9.3 Cosmology · 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 star of solar mass evolves to a red giant after the main sequence, then expels its outer layers to form a planetary nebula and leaves a white dwarf remnant.
A much more massive star becomes a red super‑giant after the main sequence, then undergoes a core collapse supernova, leaving a neutron star (or, if the core is massive enough, a black hole).

Examiner tips

  • Use the word ‘then’ to show sequence; mention red giant/super‑giant, planetary nebula, white dwarf, supernova, neutron star/black hole.
  • Show clear contrast between the two mass ranges; include all five points in order.

Common mistakes

  • Confusing planetary nebula with supernova remnants; writing that both stars become white dwarfs; omitting the neutron star/black hole remnant.

Mark scheme (5 marks)

  1. A star similar to the Sun becomes a red giant (after the main sequence)
  2. A star similar to the Sun then sheds its outer layers to form a planetary nebula / white dwarf
  3. A much more massive star becomes a red supergiant (after the main sequence)
  4. A much more massive star then explodes as a supernova
  5. The remnant of the supernova becomes a neutron star or (if massive enough) a black hole

Key terms in this question

main sequence

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