Star spectral classes


O

White-blue stars, composed by hydrogen, helium, oxygen and other ionized elements. They are very thick and bright and their superficial temperature is about 35.000K.
Example: Alnitak.

B

White-blue stars, composed by hydrogen, helium. They are very thick and bright and their superficial temperature is about 20.000K.
Example: Rigel, Spica.

A

White stars, composed by hydrogen. They are very bright and their superficial temperature goes from 8.000 to 12.000K.
Example: Sirius, Vega, Altair.

F

Yellow-white stars, composed by hydrogen, ionized calcium and potassium. Their superficial temperature is between 6.000 and 8.000K.
Example: Polar Star, Procyon.

G

Yellow stars, composed by hydrogen, helium and several metals. Their superficial temperature is 4.000-6.000K.
Example: Sun, Capella.

K

Orange stars, with presence of calcium and several metals (their spectrum is similar to that of sunspots). Their superficial temperature goes from 3.000 to 5.000K.
Example: Arcturus, Aldebaran.

M

Red stars, characterized by the oxide of titanium. Their superficial temperature is about 2.500K.
Example: Betelgeuse, Antares.

S

Red stars, characterized by the oxide of zirconium. Their superficial temperature is about 2.500K.

R

Red-orange stars, with presence of carbon compounds. Their superficial temperature is about 2.000K.

N

Dark red stars, with presence of carbon compounds. Their superficial temperature is about 1.500K.
Note: each class contains ten subdivisions numbered from 0 to 9.


Back to data page.