2.9 106 K nm
Spectral Type ~ Temperature
• Why is the study of stellar evolution difficult?
– Stars change very little over a human lifespan, so it is impossible to
follow a single star from birth to death.
• How do we attempt to overcome this difficulty?
– We observe stars at various stages of evolution, and can piece
together a description of the evolution of stars in general
– Computer models provide a “fast-forward” look at the evolution of
• Mass (how much fuel is available) tells us much about how
a star will evolve!
• Stellar Evolution can be viewed as a competition b/t gravity
1 Solar Mass Star
The Ring Nebula
Evolution of a high mass star