Trace the planetary nebula and white dwarf branch
Follow a less-massive red giant into expelled material surrounding a white dwarf remnant.
Exam scope and assessment notes
Extended only (Supplement) · Physics 0972, 2026–2028. Use supplied distances, periods and stated orbital models. Drawings are not to scale. Written practice is self-checked. Human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0972 has the same subject content as IGCSE 0625, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recall the mass-dependent giant branches.
- Distinguish a gas cloud from a compact object.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which branch follows a less-massive red giant?
What you will learn
- Follow a less-massive red giant into expelled material surrounding a white dwarf remnant.
- Distinguish the planetary nebula cloud from the central remnant and from planets.
Follow the less-massive route
In the syllabus’s less-massive route, a red giant sheds outer material that forms a planetary nebula. A white dwarf remains at its centre. The cloud and remnant are different outcomes from different parts of the evolved star; the white dwarf is not the whole extended nebula.
Despite its name, a planetary nebula is not a newly created planet or the collection of ordinary planets in a Solar System. The historical name describes an observed appearance, not a planetary classification.
Keep the endpoint distinct
A white dwarf is a compact stellar remnant that can radiate stored thermal energy as it cools. Its appearance does not imply continuing central hydrogen fusion like the earlier stable stage. Nor is a Sun-like star expected to follow the massive-star supernova branch in this syllabus model.
A schematic arrow gives evolutionary ordering, not an instantaneous event or a diagram whose equal boxes measure equal durations, radii or masses. Use the initial-mass condition when selecting this route.
Pause and explain
Is a planetary nebula a planet?
Worked example
Label the extended cloud and compact centre after a less-massive red giant sheds its outer layers.
Show the worked solution
- Identify expelled outer material.
- Name the surrounding planetary nebula.
- Name the central white dwarf remnant.
Answer Cloud: planetary nebula; centre: white dwarf.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Complete stable less-massive star → red giant → __ with __ at its centre.
Give me a hint
Identify the expelled cloud separately from the compact remnant.
Compare my reasoning
- Follow the less-massive condition.
- Name a planetary nebula as the cloud.
- Name a white dwarf at the centre.
Planetary nebula with a white dwarf at its centre.
Look for these in your work
- Name both outcomes.
- Keep cloud and centre separate.
Explain why the phrase planetary nebula does not prove a new planet has formed.
Give me a hint
Use the physical origin, not the sound of its historical name.
Compare my reasoning
- Material is shed from an evolved star.
- It forms an extended gas cloud.
- The centre is a stellar remnant, not evidence of a new planet.
It describes expelled stellar gas; the name does not establish planet formation.
Look for these in your work
- State the cloud origin.
- Avoid name-based classification.
A Sun-like star is placed on a poster ending in a supernova and black hole. Repair the route.
Give me a hint
Select the less-massive branch before choosing its endpoint.
Compare my reasoning
- Use a red-giant stage.
- Then identify a planetary nebula.
- Place a white dwarf at the centre.
Sun-like stable star → red giant → planetary nebula and central white dwarf.
Look for these in your work
- Use the correct branch.
- Include both cloud and remnant.
Common mistakes
- Planetary nebula does not mean planet.
- White dwarf and nebula are distinct.
- The Sun-like branch does not end in a massive-star supernova.
What can you explain now?
Is a planetary nebula a planet?
Compare with the explanation
No; it is expelled gas surrounding a remnant
The name does not classify the cloud as an orbiting rocky or giant planet.
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Make it stick
Distinguish the planetary nebula cloud from the central remnant and from planets.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.