| Spectral class | Color | Temperature (K) | Spectral lines | Examples |
|---|
| O | Blue-violet | 30,000–50,000 | Ionized atoms, especially helium | Naos (ζ Puppis), Mintaka (δ Orionis) |
| B | Blue-white | 11,000–30,000 | Neutral helium, some hydrogen | Spica (α Virginis), Rigel (β Orionis) |
| A | White | 7500–11,000 | Strong hydrogen, some ionized metals | Sirius (α Canis Majoris), Vega (α Lyrae) |
| F | Yellow-white | 5900–7500 | Hydrogen and ionized metals such as calcium and iron | Canopus (α Carinae), Procyon (α Canis Minoris) |
| G | Yellow | 5200–5900 | Both neutral and ionized metals, especially ionized calcium | Sun, Capella (α Aurigae) |
| K | Orange | 3900–5200 | Neutral metals | Arcturus (α Boötis), Aldebaran (α Tauri) |
| M | Red-orange | 2500–3900 | Strong titanium oxide and some neutral calcium | Antares (α Scorpii), Betelgeuse (α Orionis) |
| L | Red | 1300–2500 | Neutral potassium, rubidium, and cesium, and metal hydrides | Brown dwarf Teide 1 |
| T | Red | 700–1300 | Methane, strong neutral potassium and some water (H2O) | Brown dwarfs Gliese 229B, HD 3651B |
| Y | Red | below 600 | Possibly ammonia | Brown dwarfs CFBDS J005910.90–011401.3, WISE 1828+2650 |