max

6 nmK 109.2

λ⋅×

=T L=4R2T4

Spectral Type ~ Temperature

• L~M3.5

Stellar Evolution

• 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 stars.

• 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 and pressure.

1 Solar Mass Star

Fusionbegins

The Ring Nebula

Evolution of a high mass star