Alderamin

Alderamin (Alpha Cephei) is a white Class A star, evolving off of the main sequence into a subgiant, probably on its way to becoming a red giant as its hydrogen supply runs low.

With a surface temperature of 7,740 K, it is slightly variable with a range in brightness of 0.06 magnitude, and is listed as a Delta Scuti variable.

Alderamin has a very high rotation speed of at least 246 km/s, completing one complete revolution in less than 12 hours, with such a rapid turnover appearing to inhibit the differentiation of chemical elements usually seen in such stars. α Cep is also known to emit an amount of X radiation, which along with other indicators suggests the existence of considerable magnetic activity — something unexpected (though not at all unusual) for a fast rotator.