Stellar Evolution and Galaxies
Stellar evolution describes the life cycle of stars from nebula to final remnant, while galaxy formation and structure reveal the large-scale organisation of matter in the universe.
What You Need to Know
Key Concept Diagram
Stars form in nebulae — clouds of gas and dust that collapse under gravity
The main sequence is the longest phase of a star's life, where hydrogen fusion occurs in the core
The mass of a star determines its fate: low-mass stars become white dwarfs; high-mass stars become neutron stars or black holes
A supernova is the explosive death of a massive star that distributes heavy elements into space
Galaxies are classified as spiral, elliptical, or irregular based on their shape
Key Vocabulary
Nebula
A cloud of gas and dust in space; the birthplace of stars
Main sequence
The stage in a star's life when it is fusing hydrogen to helium in its core
Supernova
A powerful stellar explosion marking the end of a massive star's life
Black hole
A region of space with gravity so strong that nothing, not even light, can escape
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
What is the energy source of a main sequence star?
Question 2
What determines the fate of a star at the end of its life?
Question 3
The Milky Way is classified as which type of galaxy?
Key Concepts Summary
- ●Stars form in nebulae — clouds of gas and dust that collapse under gravity
- ●The main sequence is the longest phase of a star's life, where hydrogen fusion occurs in the core
- ●The mass of a star determines its fate: low-mass stars become white dwarfs; high-mass stars become neutron stars or black holes
- ●A supernova is the explosive death of a massive star that distributes heavy elements into space
- ●Galaxies are classified as spiral, elliptical, or irregular based on their shape