A star of spectral type F, slightly hotter and more massive than the Sun, and white in colour. On the main sequence, F-type stars have temperatures of 6100–7200 K, while supergiants are a few hundred degrees cooler. Masses are 1.2–1.6 solar masses, and luminosities 2–6.5 times the Sun’s on the main sequence, but F-type supergiants have masses up to 12 solar masses and luminosities up to 32 000 times the Sun’s. The hydrogen Balmer lines weaken dramatically from spectral type F0 to F9, while the calcium H and K lines increase in strength and many other metal lines start to become visible. Polaris and Procyon are F-type stars.