Class 

Spectrum 

Color 

Temperature (K)

O

Ionized and neutral helium; weakened hydrogen

bluish

31,500 – 49,000

B

Neutral helium, stronger hydrogen

blue-white

10,000 – 31,500

A

Strong hydrogen, ionized metals

white

7,500 -10,000

F

Weaker hydrogen, ionized metals

yellowish-white

6,000 – 7,500

G

Still weaker hydrogen, ionized and neutralized metals

yellowish

5,300 – 6,000

K

Weak hydrogen, neutral metals

orange

3,800 – 5,300

M

Little or no hydrogen, neutral metals, molecules

reddish

2,100 – 3,800

L

No hydrogen, metallic hybrids, alkalai metals

red-infrared

1,200 – 2,100

T

Methane bands

infrared

Under 1,200