Stellar classification

In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines. Each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere. The spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photosphere's temperature and density.

Uses material from the Wikipedia article "Stellar classification", which is released under the Creative Commons BY-SA 3.0.
O
Effective temperature
≥ 25,000 K
Solar radius
≥ 6.6 R
Solar mass
≥ 16 M
B
Effective temperature
10,000–25,000 K
Solar radius
1.8–6.6 R
Solar mass
2.1–16 M
A
Effective temperature
7,500–10,000 K
Solar radius
1.4–1.8 R
Solar mass
1.4–2.1 M
F
Effective temperature
6,000–7,500 K
Solar radius
1.15–1.4 R
Solar mass
1.04–1.4 M
G
Effective temperature
5,000–6,000 K
Solar radius
0.96–1.15 R
Solar mass
0.8–1.04 M
K
Effective temperature
3,500–5,000 K
Solar radius
0.7–0.96 R
Solar mass
0.45–0.8 M
M
Effective temperature
2,000–3,500 K
Solar radius
≤ 0.7 R
Solar mass
0.08–0.45 M
L
Effective temperature
1,200 to 2,000 K
 
Solar mass
≤ 0.08 M
T
Effective temperature
750-1,200 K
 
 
Y
Effective temperature
≤ 750 K
 
 
C
Effective temperature
≤ 3,000 K
 
 
S
Effective temperature
2,000-3,000 K
 
 
W
Effective temperature
30,000-200,000 K
 
 
D
Effective temperature
4,000-150,000 K