Iota Cephei (ι Cephei, ι Cep) is a star in the northern constellation Cepheus. Based upon an annual parallax shift of 28.29 mas as seen from the Earth,[1] it is located about 115 light years from the Sun. The star is visible to the naked eye with an apparent visual magnitude of 3.5.[2]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 22h 49m 40.817s[1] |
| Declination | +66° 12′ 01.46″[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) | −12.763±0.0008[4] km/s |
| Proper motion (μ) | RA: −65.89[1] mas/yr Dec.: −125.17[1] mas/yr |
| Parallax (π) | 28.29 ± 0.10 mas[1] |
| Distance | 115.3 ± 0.4 ly (35.3 ± 0.1 pc) |
| Absolute magnitude (MV) | 0.76[3] |
| Details[5] | |
| Mass | 2.15±0.23 M☉ |
| Radius | 11.08±0.16 R☉ |
| Luminosity | 57.0±0.6 L☉ |
| Surface gravity (log g) | 2.69±0.06 cgs |
| Temperature | 4,768±33 K |
| Metallicity [Fe/H] | +0.05±0.10 dex |
| Rotational velocity (v sin i) | 10[6] km/s |
| Age | 1.2±0.6 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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.[8] 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.[5]
Pole star
editIota 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 |
References
edit- ^ a b c d e f 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, S2CID 18759600.
- ^ a b c d 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 (3): 667–679, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
- ^ a b c 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, S2CID 119529768.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b 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, S2CID 59334290.
- ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1): 1, Bibcode:1970CoAsi.239....1B.
- ^ "iot Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-05-06.
- ^ 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, S2CID 119182458.