Epoch J2000 Equinox J2000
|Right ascension||22h 10m 51.277s|
|Declination||+58° 12′ 04.55″|
|Apparent magnitude (V)||3.39|
|Spectral type||K1.5 Ib|
|B−V color index||+1.57|
|Proper motion (μ)||RA: 13.52 ± 0.10 mas/yr
Dec.: 5.24 ± 0.09 mas/yr
|Parallax (π)||3.90 ± 0.10 mas|
|Distance||840 ± 20 ly
(256 ± 7 pc)
|Surface gravity (log g)||0.75 cgs|
|Metallicity [Fe/H]||+0.2 dex|
|Rotational velocity (v sin i)||8 km/s|
|Age||50 million years|
Zeta Cephei is an orange supergiant star of spectral type K1.5 Ib, with a surface temperature of 3,853 K and eight times more massive then the Sun. The luminosity of Zeta Cephei is approximately 3600 times that of the Sun. At a distance of about 840 light-years, Zeta Cephei has an apparent magnitude (m) of 3.39 and an absolute magnitude (M) of -3.35. 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 the edge of the 8 to 10 solar mass limit at which stars develop iron cores and then explode as supernovae, Zeta Cephei's most likely fate is to produce a very massive white dwarf near the Chandrasekhar limit (1.4 solar mass) at which such dense remnants can survive. If Zeta Cephei is a binary star; i.e., if there is a stellar companion, and it is close enough to feed sufficient matter to the white-dwarf-to-be, it is marginally possible that the limit could be overflowed, resulting in the white dwarf's collapse and a Type Ia supernova explosion.
- van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
- Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics 352: 495–507, Bibcode:1999A&A...352..495M
- Hekker et al. (2008). "Precise radial velocities of giant stars. IV. A correlation between surface gravity and radial velocity variation and a statistical investigation of companion properties". Astronomy and Astrophysics 480 (1): 215–222. arXiv:0809.0359. Bibcode:2008A&A...480..215H. doi:10.1051/0004-6361:20078321.
-  by Jim Kaler