出典:Wikipedia
出典:『Wikipedia』 (2011/04/09 15:39 UTC 版)
Delta Cephei (δ Cep, δ Cephei) is a binary star system approximately 891 light-years away in the constellation of Cepheus (the King). Delta Cephei is the prototype of the Cepheid variable stars, and it is among the closest stars of this type to the Sun (with Polaris being closer). Its variability was discovered by John Goodricke in 1784, the second Cepheid variable discovered following Eta Aquilae earlier the same year.