Zeta Cephei
{{short description|Star in the constellation Cepheus}}
{{Starbox begin
| name = Zeta Cephei
}}
{{Starbox image
| image=
{{Location mark
|image=Cepheus constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=12|mark_link=Zeta Cephei|x=679|y=1058
}}
|caption=Location of ζ Cephei (circled)
}}
{{Starbox observe
| epoch = J2000
| equinox = J2000
| constell = Cepheus
}}
{{Starbox character
| type = Red supergiant
| variable = Eclipsing binary?
}}
{{Starbox astrometry
| radial_v =
| prop_mo_ra = {{val|13.359|0.148}}
| prop_mo_dec = {{val|5.275|0.183}}
| parallax = 3.2972
| p_error = 0.1456
| parallax_footnote ={{cite Gaia DR3|2199493438511811712}}
| dist_pc = {{val|304.5|15.7|14.1}}
| dist_ly = {{val|992.7|51.2|46}}
}}
{{Starbox detail
| radius = {{Val|172.7|7.5|8.3}}
| luminosity = {{val|10024|1052|fmt=commas}}
| temperature = {{val|4,393|58|fmt=commas}}
| age_myr =
}}
{{Starbox catalog
| names = 21 Cephei, HR 8465, BD+57°2475, HD 210745, GCTP 5139.00, SAO 34137, FK5 836, HIP 109492, Gaia DR2 2199493438511811712, Gaia DR3 2199493438511811712
}}
{{Starbox reference
|Simbad=Zeta+Cephei
}}
{{Starbox end}}
Zeta Cephei (ζ Cep, ζ Cephei) is a red supergiant star, located about 1000 light-years away in the constellation of Cepheus. Zeta Cephei marks the left shoulder of Cepheus, the King of Ethiopia. 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 (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.
At a mass of {{Solar mass|10.1|link=y}}, 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.
Possible companion star
Hekker et al. (2008) have detected a periodicity of 533 days, 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
{{reflist|refs=
{{cite journal | author=Hekker| display-authors=etal| title=Precise radial velocities of giant stars. IV. A correlation between surface gravity and radial velocity variation and a statistical investigation of companion properties| journal=Astronomy and Astrophysics | volume=480| issue=1 | pages=215–222 | year=2008| bibcode=2008A&A...480..215H|doi = 10.1051/0004-6361:20078321 |arxiv = 0801.0741 | s2cid=33442610}}
}}
{{Stars of Cepheus}}
{{DEFAULTSORT:Zeta Cephei}}