Zeta_Cephei
Zeta Cephei
Star in the constellation Cepheus
Zeta Cephei (ζ Cep, ζ Cephei) is a star in the constellation of Cepheus. Zeta Cephei marks the left shoulder of Cepheus, the King of Joppa (Ethiopia).[clarification needed] It is one of the fundamental stars of the MK spectral sequence, defined as type K1.5 Ib.
Zeta Cephei is a red supergiant star with a surface temperature of 4,393 K and a radius of 172 R☉.[7] The luminosity of Zeta Cephei is approximately 10,000 times that of the Sun.[7] At a distance of about 840 light-years,[10] Zeta Cephei has an apparent magnitude (m) of 3.4 and an absolute magnitude (M) of -4.7. The star has a metallicity approximately 1.6 times that of the Sun; i.e., it contains 1.6 times as much heavy-element material as the Sun.
Hekker et al. (2008) have detected a periodicity of 533 days, hinting at the possible presence of an as yet unseen companion.[11] It is listed as a possible eclipsing binary with a very small amplitude.[4]