Iota Cephei

Iota Cephei (ι Cephei, ι Cep) is a 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]

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]
Characteristics
Spectral type K0 III[3]
U−B color index +0.924[2]
B−V color index +1.053[2]
Astrometry
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]
Details[4]
Mass2.15±0.23 M☉
Radius11.08±0.16 R☉
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
SIMBADdata

It is a K-type giant star with a stellar classification of K0 III.[3] It is currently at an evolutionary stage known as the red clump, indicating that it is generating energy through the fusion of helium at its core.[7] It has 11 times the Sun's radius and about 2.15 times the mass of the Sun. Its luminosity is 57 times that of the Sun, and its surface has an effective temperature of 4,768 K.[4]

Pole star

Iota Cephei is located within 5° of the precessional path traced across the celestial sphere by the Earth's North pole. In about 3,000 years, it will be one of the closest visible stars to the celestial north pole, along with Alfirk which will also be within 5° of the precessional path, on the other side.

Preceded by Pole Star Succeeded by
Errai 5200AD to 7500AD
with
Alfirk		 Alderamin
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References
  1. 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. 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. 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. 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, hdl:10722/215277.
  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. "iot Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-05-06.
  7. 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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