Zeta Cephei
Zeta Cephei is a red supergiant star in the northern constellation of Cepheus. Its name is a Bayer designation that is Latinized from ζ Cephei, and abbreviated Zeta Cep or ζ Cep. With an apparent visual magnitude of 3.35, it is a third-magnitude star that is visible to the naked eye. Based on parallax measurements, it is located about 1000 light-years away from the Earth. Zeta Cephei marks the left shoulder of Cepheus, a mythical King of Aethiopia. It is one of the fundamental stars of the MK spectral sequence, defined as type K1.5 Ib.
Characteristics
Zeta Cephei has a spectral classification of K1.5Ib, indicating that it is a lower luminosity red supergiant star. It is about 173 times larger than the Sun and has a surface temperature of 4,393 K. The luminosity of Zeta Cephei is approximately 10,000 times that of the Sun. At a distance of about 840 light-years, Zeta Cephei has an apparent magnitude of 3.4 and an absolute magnitude of -3.7. The star has a metallicity similar to the Sun.At a mass of, Zeta Cephei might end its life in a core-collapse supernova, and has been listed as a likely pre-supernova candidate by a 2022 study. It could also provide observable pre-supernova neutrino signals, just hours before the core collapses.
Hekker et al. have detected a periodicity of 533 days, hinting at the possible presence of an as yet unseen companion. It is listed as a candidate eclipsing binary with a very small amplitude. However, spectroscopic measurements made from 1993 to 2015 do not support the presence of the companion.