Stellar Classification Basics

Front

O-type stars

Back

Hottest, blue, massive

Front

B-type stars

Back

Blue-white, very luminous

Front

A-type stars

Back

White, strong hydrogen lines

Front

F-type stars

Back

Yellow-white, moderate hydrogen lines

Front

G-type stars

Back

Yellow, like the Sun

Front

K-type stars

Back

Orange, cooler than Sun

Front

M-type stars

Back

Red, coolest, most common

Front

Spectral classes

Back

O, B, A, F, G, K, M

Front

Hertzsprung-Russell Diagram

Back

Stars plotted by brightness and temperature

Front

Luminosity classes

Back

I-V, supergiants to dwarfs