Astrophysics: Star Life Cycles
Stars form from clouds of gas and dust (nebulae) and evolve through a life cycle determined by their mass. Understanding stellar evolution explains the origins of chemical elements.
What You Need to Know
Key Concept Diagram
Stars form from gravitational collapse of nebulae; nuclear fusion begins in the core
Main sequence: hydrogen fuses to helium; the Sun is currently a main sequence star
Massive stars end as supernovae, forming neutron stars or black holes
Lower mass stars become red giants, then white dwarfs
Key Vocabulary
Nebula
A cloud of gas and dust in space from which stars form
Main sequence
The stable phase of a star's life when it fuses hydrogen into helium
Supernova
A massive stellar explosion marking the death of a high-mass star
White dwarf
The dense, Earth-sized remnant of a low-mass star after it expels its outer layers
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 like our Sun?
Question 2
What is the likely fate of a very massive star (much larger than the Sun)?
Question 3
Elements heavier than iron are formed:
Key Concepts Summary
- ●Stars form from gravitational collapse of nebulae; nuclear fusion begins in the core
- ●Main sequence: hydrogen fuses to helium; the Sun is currently a main sequence star
- ●Massive stars end as supernovae, forming neutron stars or black holes
- ●Lower mass stars become red giants, then white dwarfs