© Lloyd

A Star, like the Sun, is a luminous sphere of plasma, at least on the exterior.

A plot of the temperature of many stars against their luminosities is known as the Hertzsprung–Russell diagram (H–R diagram).

O >30,000K
B 10,000–30,000K
A 7,300–10,000K
F 6,000–7,300K
G 5,300–6,000K
K 4,000–5,300K
M 2,600–4,000K

I Supergiants
II Luminous giants
III Giants
IV Subgiants
V Main sequence dwarfs
VI Subdwarf
VII White Dwarf

Variable Stars

Pulsars

Quasars