8.1.5
Life Cycle of a Star
Life Cycle of a Star like the Sun
Life Cycle of a Star like the Sun
Every star has a life cycle that depends on its size. All stars begin their life cycle in the same way as the Sun. Gravity pulls nebulae (more than 1 nebula) together to form a protostar. This protostar then becomes a main sequence star. If a star is about the same size as the Sun, a star’s lifecycle is like this:
Main sequence
Main sequence
- In a main sequence star, hydrogen nuclei are fused together to form helium.
- This releases energy as heat and light.
Red giant
Red giant
- Eventually all the hydrogen fuel runs out.
- The star then cools and expands, becoming a red giant.
- The star then starts to fuse together helium nuclei to release energy.
White dwarf
White dwarf
- As the helium fuel runs out, the outward forces reduce in size and the star collapses inwards.
- This causes its temperature to increase.
- A white dwarf is formed, which is the hot core of the star.
Black dwarf
Black dwarf
- When the star completely cools, the star becomes a black dwarf.
- A black dwarf doesn’t emit (send out) any light or heat.
Life Cycle of a Star Much Bigger than the Sun
Life Cycle of a Star Much Bigger than the Sun
A star's life cycle depends on its size. All stars begin their life cycle like the Sun. Gravity pulls nebulae (more than 1 nebula) together to form a protostar, which becomes a main sequence star. If a star is much bigger than the Sun, its life cycle looks like this:
Red supergiant
Red supergiant
- Nuclear fusion changes more and more of the star’s mass into energy.
- The star expands into a red supergiant.
Supernova
Supernova
- The largest stars explode in a supernova.
- A supernova produces elements heavier than iron and scatters them throughout the universe.
Black hole or neutron star
Black hole or neutron star
- The supernova leaves behind either a black hole or a neutron star.
Creation of Elements
Creation of Elements
The fusion processes in stars produce all of the naturally occurring elements. Different size stars produce different elements.
All stars
All stars
- All stars fuse hydrogen nuclei into helium in nuclear fusion.
Large stars
Large stars
- Larger stars fuse hydrogen nuclei into lithium and other light metals.
Supernovae
Supernovae
- A supernova produces enough energy for hydrogen nuclei to form elements heavier than iron.
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
Jump to other topics
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
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