Zeta Cephei (ζ Cep, ζ Cephei) is a

red supergiant Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelg ...

star, located about 1000

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s away in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

of Cepheus. Zeta Cephei marks the left

shoulder The human shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder m ...

of Cepheus, the King of

Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...

. 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 ''Spectral'' is a 2016 Hungarian-American military science fiction action film co-written and directed by Nic Mathieu. Written with Ian Fried & George Nolfi, the film stars James Badge Dale as DARPA research scientist Mark Clyne, with Max M ...

of K1.5Ib, indicating that it is a lower luminosity

star. It is about 173 times larger than the Sun and has a surface temperature of 4,393 K. The

luminosity Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...

of Zeta Cephei is approximately 10,000 times that of the Sun. At a distance of about 840

s, Zeta Cephei has an apparent magnitude (''m'') of 3.4 and an absolute magnitude (''M'') of -4.7. The star has a

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

approximately 1.6 times that of the Sun; i.e., it contains 1.6 times as much heavy-element material as the Sun. At a mass of , Zeta Cephei might end its life in a

core-collapse supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion. The original obj ...

, and has been listed as a likely pre-supernova candidate by a 2022 study. It could also provide observable pre-supernova

neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...

signals, just hours before the core collapses.

Possible companion star

Hekker et al. (2008) have detected a periodicity of 533

day A day is the time rotation period, period of a full Earth's rotation, rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, ...

s, hinting at the possible presence of an as yet unseen companion. It is listed as a possible eclipsing binary with a very small amplitude.

References

{{DEFAULTSORT:Zeta Cephei Cepheus (constellation) Cephei, Zeta Cephei, 21 210745 105199 8465 K-type supergiants Durchmusterung objects