AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
A star goes through a life cycle. The life cycle is determined by the size…
Full specification wording
The life cycle of a star: A star goes through a life cycle. The life cycle is determined by the size of the star.
Every star follows the same opening: nebula, protostar, main sequence.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 1 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Every star follows the same opening: nebula, protostar, main sequence. What happens afterwards is decided by the mass of the star, which is what the specification means by size. Stars about the size of the Sun swell into a red giant, then shed their outer layers and shrink into a white dwarf, which slowly cools into a black dwarf. Stars much more massive than the Sun swell into a red supergiant and then explode as a supernova, leaving behind either a neutron star or, for the most massive of all, a black hole. Mass also sets the pace, because a more massive star uses up its hydrogen faster and has a shorter main sequence life, so the biggest stars are also the shortest lived.
What earns the marks
- All stars starting as a nebula and passing through the protostar and main sequence stages.
- The mass of the star deciding which route it takes afterwards.
- A correct route for a star of about the mass of the Sun.
- A correct route for a star much more massive than the Sun.
Common mistakes and how to put them right
Thinking a bigger star lives longer, when a more massive star uses its hydrogen up faster.
Saying that the Sun will end its life as a supernova.
Putting red giant and white dwarf in the wrong order.
Writing that the life cycle depends on the star's temperature or brightness rather than on its mass.
Exam tips
- Sketch the two branches as a flow chart and learn them as a pair, not as one long list.
- Read the stem for the mass of the star before choosing which route to describe.
- Use the full names, red supergiant and white dwarf, because giant on its own is ambiguous.
Try the lesson
The start of the The life cycle of a star: A star goes through a life cycle. The life cycle is determined by the size of the star. lesson, made from checked teaching notes for this specification point.
Have a go first
Which property of a star determines the path its life cycle will take?
Listen
Every star follows the same opening: nebula, protostar, main sequence. What happens afterwards is decided by the mass of the star, which is what the specification means by size. Stars about the size of the Sun swell into a red giant, then shed their outer layers and shrink into a white dwarf, which slowly cools into a black dwarf. Stars much more massive than the Sun swell into a red supergiant and then explode as a supernova, leaving behind either a neutron star or, for the most massive of all, a black hole. Mass also sets the pace, because a more massive star uses up its hydrogen faster and has a shorter main sequence life, so the biggest stars are also the shortest lived. A strong answer earns marks for these points. all stars starting as a nebula and passing through the protostar and main sequence stages. the mass of the star deciding which route it takes afterwards. a correct route for a star of about the mass of the Sun. a correct route for a star much more massive than the Sun. Exam tip: Sketch the two branches as a flow chart and learn them as a pair, not as one long list.
See it
Key words
Say what each word means before you turn the card.
stellar life cycle
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mass decides the route
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main sequence
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two branches
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See every definition
- stellar life cycle
- The series of stages a star goes through, which is determined by the size of the star.
- mass decides the route
- The mass of the star decides which route it takes after the main sequence.
- main sequence
- One of the stages that every star passes through before the two routes separate.
- two branches
- The two routes that separate after the main sequence, which should be sketched as a flow chart and learned as a pair.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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