Iota Cephei

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Iota Cephei
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cepheus
Right ascension 22h 26m 42.40624s[1]
Declination +78° 47′ 09.0725″[1]
Apparent magnitude (V) 3.507[2]
Spectral type K0 III[3]
U−B color index +0.924[2]
B−V color index +1.053[2]
Radial velocity (Rv)−12.59±0.20[3] km/s
Proper motion (μ) RA: −13.33[1] mas/yr
Dec.: −36.95[1] mas/yr
Parallax (π)15.83 ± 0.23[1] mas
Distance206 ± 3 ly
(63.2 ± 0.9 pc)
Absolute magnitude (MV)0.76[3]
Mass2.15±0.23 M
Radius11.08±0.16 R
Diameter11.08±0.16 D
Luminosity57.0±0.6 L
Surface gravity (log g)2.69±0.06 cgs
Temperature4,768±33 K
Metallicity [Fe/H]+0.05±0.10 dex
Rotational velocity (v sin i)10[5] km/s
Age1.2±0.6 Gyr
Other designations
ι Cep, 32 Cep, BD+65° 1814, HD 216228, HIP 112724, HR 8694, SAO 20268[6]
Database references

Iota Cephei (ι Cephei, ι Cep) is a solitary[7] star in the northern constellation Cepheus. Based upon an annual parallax shift of 15.83 mas as seen from the Earth,[1] it is located about 206 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 3.5.[2]

This is a K-type giant star with a stellar classification of K0 III.[3] It is currently at an evolutionary stage known as a red clump, indicating that it is generating energy through the fusion of helium at its core.[8] This star has 11 times the Sun's radius and about 2.15 times the mass of the Sun. It is emitting 57 times as much luminosity as the Sun, which is being radiated from its photosphere at an effective temperature of 4,768 K.[4]

Pole Star[edit]

Iota Cephei is a visible star located within 5° of the precessional path traced across the celestial sphere by the Earth's North pole. During the same period Alfirk will also be within 5° of the precessional path, on the other side so that both are in contention as pole stars, a title currently held by unambiguously by Polaris.

Preceded by Pole Star Succeeded by
Errai 5200AD to 7500AD


  1. 1.0 1.1 1.2 1.3 1.4 1.5 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.
  2. 2.0 2.1 2.2 2.3 Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants", Monthly Notices of the Royal Astronomical Society 172: 667–679, Bibcode 1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
  3. 3.0 3.1 3.2 3.3 Hekker, S. et al. (August 2006), "Precise radial velocities of giant stars. I. Stable stars", Astronomy and Astrophysics 454 (3): 943–949, arXiv:astro-ph/0604502, Bibcode 2006A&A...454..943H, doi:10.1051/0004-6361:20064946.
  4. 4.0 4.1 Reffert, Sabine et al. (2015), "Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity", Astronomy & Astrophysics 574: A116, arXiv:1412.4634, Bibcode 2015A&A...574A.116R, doi:10.1051/0004-6361/201322360.
  5. Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago 239 (1), Bibcode 1970CoAsi.239....1B.
  6. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  7. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, arXiv:0806.2878, Bibcode 2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  8. Tautvaišienė, G. et al. (December 2010), "C, N and O abundances in red clump stars of the Milky Way", Monthly Notices of the Royal Astronomical Society 409 (3): 1213–1219, arXiv:1007.4064, Bibcode 2010MNRAS.409.1213T, doi:10.1111/j.1365-2966.2010.17381.x.

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