Spectral Class B
Spectral Class A
Spectral Class F
Spectral Class G
Spectral Class K
Spectral Class M
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Red 2,500º - 3,500º K Ionized Atoms, helium 0.2 Sols 0.3 Sols 0.04 +15 78% of stars 200 billion years Betelgeuse, Proxima Centauri, Wolf 359 |
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Orange 3,500º - 5,000º K Neutral metals 0.8 Sols 0.7 Sols 0.4 +10 13% of stars 50 billion years Arcturus, Aldebaran, Alpha Centauri |
Spectral Class O
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Dark blue/violet 28,000º - 50,000º K Ionized atoms, helium 60 Sols 15 Sols 1,400,000 -3 0.0000003125% of all stars 10 million years Mintaka, Kalidar, Zeta Puppis |
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Yellow 5,000º - 6,000º K Ionized calcium, neutral and ionized metals 1.1 Sols 1.1 Sols 1.2 +5 8% of stars 10 billion years Sol, Ka'Tula, Capella |
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
White 6,000º - 7,500º K Hydrogen and ionized metals, calcium and iron 1.7 Sols 1.3 Sols 6.0 +3 3.1% of stars 3 billion years Canopus, Procyon |
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Light Blue 7,500º - 10,000º K Strong hydrogen and ionized metals 3.2 Sols 2.5 Sols 80.0 +1 0.63% of stars 1 billion years Vega, Sirius |
Color Surface Temp Composition Mass Radius Luminosity Magnitude Abundance Lifetime Example |
Blue 10,000º - 28,000º K Neutral helium, some hydrogen 18 Sols 7 Sols 20,000 -6 0.13% of stars 100 million years Rigel, Alpha Eridani |
| Spectral Classification |
Spectral classification is the classification of stars based upon the temperature of the
photosphere. Each spectral class is further divided into 10 subclasses, ranging from 0
(hottest) to 9 (coolest). Stars are also placed into one of six categories based upon
luminosity: 1a (luminous supergiants), 1b (less luminous supergiants), II (luminous giants), III
(normal giants), IV (subgiants), and V (main sequence and dwarf stars).
For example, Sol is classified as type G2V. This indicates that is a Spectral Class G star of
considerable temperature, and that it is a part of the main sequence.
photosphere. Each spectral class is further divided into 10 subclasses, ranging from 0
(hottest) to 9 (coolest). Stars are also placed into one of six categories based upon
luminosity: 1a (luminous supergiants), 1b (less luminous supergiants), II (luminous giants), III
(normal giants), IV (subgiants), and V (main sequence and dwarf stars).
For example, Sol is classified as type G2V. This indicates that is a Spectral Class G star of
considerable temperature, and that it is a part of the main sequence.