Hertzsprung-Russell (HR) Diagram

Life Cycle of Stars

A good link


I. Plots Luminosity vs Color

II. Luminosity

A. starís intrinsic brightness
B. 1012 difference from brightest to dimmest
C. Sun is the standard
D. approx. 5% are brighter
III. Color
A. measures temperature
B. O, B, A, F, G, K, M
C. These are broken down from 0-9
D. Sun is a G2 (G3 in many astronomy stories)
E. Mass determines temperature
F. More mass shorter lifetime

IV. Main Sequence

A. the diagonal band
B. 90% of all stars in galaxy
C. fusing H to He
V. The others
A. red giants less than 1%
1. big
2. cooler
B. white dwarfs approx. 10%

1. hot but cool with age
2. they can be F, G, or K