Astronomy:Zeta Cephei

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Short description: Star in the constellation Cepheus
Zeta Cephei
Location of ζ Cephei (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Cepheus
Right ascension  22h 10m 51.277s[1]
Declination +58° 12′ 04.54″[1]
Apparent magnitude (V) 3.35[2]
Characteristics
Evolutionary stage Red supergiant[3]
Spectral type K1.5 Ib[4]
B−V color index +1.55[2]
Astrometry
Proper motion (μ) RA: 13.359±0.148[1] mas/yr
Dec.: 5.275±0.183[1] mas/yr
Parallax (π)3.2972 ± 0.1456[1] mas
Distance992.7+51.2
−46 ly
(304.5+15.7
−14.1 pc)
Absolute magnitude (MV)−4.7[3]
Details
Mass10.1±0.1[5] M☉
Radius172.7+7.5
−8.3[6] R☉
Luminosity10,024±1,052[6] L☉
Surface gravity (log g)0.75[7] cgs
Temperature4,393±58[6] K
Metallicity [Fe/H]+0.04[6] dex
Rotational velocity (v sin i)10.64[8] km/s
Other designations
21 Cephei, BD+57°2475, FK5 836, Gaia DR2 2199493438511811712, HD 210745, HIP 109492, HR 8465, SAO 34137[9]
Database references
SIMBADdata

Zeta Cephei is a red supergiant star in the northern constellation of Cepheus. Its name is a Bayer designation that is Latinized from ζ Cephei, and abbreviated Zeta Cep or ζ Cep. With an apparent visual magnitude of 3.35,[2] it is a third-magnitude star that is visible to the naked eye. Based on parallax measurements, it is located about 1000 light-years away from the Earth. Zeta Cephei marks the left shoulder of Cepheus, a mythical King of Aethiopia. 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,[4] 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.[6] The luminosity of Zeta Cephei is approximately 10,000 times that of the Sun.[6] At a distance of about 840 light-years,[10] Zeta Cephei has an apparent magnitude (m) of 3.4 and an absolute magnitude (M) of -3.7.[11] The star has a metallicity similar to the Sun.[6]

At a mass of 10.1 M☉, 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.[5]

Hekker et al. (2008) have detected a periodicity of 533 days, hinting at the possible presence of an as yet unseen companion.[12] It is listed as a candidate eclipsing binary with a very small amplitude.[13] However, spectroscopic measurements made from 1993 to 2015 do not support the presence of the companion.[11]

References

  1. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 Ducati, J. R. (2002-01-01). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system.". VizieR Online Data Catalog 2237. Bibcode: 2002yCat.2237....0D. https://ui.adsabs.harvard.edu/abs/2002yCat.2237....0D.  Zeta Cephei's database entry at VizieR.
  3. ↑ 3.0 3.1 Luck, R. E. (1982). "The chemical composition of late-type supergiants. IV - Homogeneous abundances and galactic metallicity trends". Astrophysical Journal 256: 177. doi:10.1086/159895. Bibcode: 1982ApJ...256..177L. 
  4. ↑ 4.0 4.1 Morgan, W. W.; Keenan, P. C. (1973). "Spectral Classification". Annual Review of Astronomy and Astrophysics 11: 29–50. doi:10.1146/annurev.aa.11.090173.000333. Bibcode: 1973ARA&A..11...29M. 
  5. ↑ 5.0 5.1 Machado, L. N. et al. (2022-08-12). "Pre-supernova Alert System for Super-Kamiokande" (in en). The Astrophysical Journal 935 (1): 40. doi:10.3847/1538-4357/ac7f9c. ISSN 0004-637X. Bibcode: 2022ApJ...935...40M. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 Baines, Ellyn K. et al. (November 2021). "Angular Diameters and Fundamental Parameters of Forty-Four Stars from the Navy Precision Optical Interferometer". The Astronomical Journal 162 (5): 198. doi:10.3847/1538-3881/ac2431. ISSN 0004-6256. Bibcode: 2021AJ....162..198B. 
  7. ↑ Mallik, Sushma V. (December 1999). "Lithium abundance and mass". Astronomy and Astrophysics 352: 495–507. Bibcode: 1999A&A...352..495M. 
  8. ↑ Hekker, S.; Meléndez, J. (2007). "Precise radial velocities of giant stars. III. Spectroscopic stellar parameters". Astronomy and Astrophysics 475 (3): 1003. doi:10.1051/0004-6361:20078233. Bibcode: 2007A&A...475.1003H. 
  9. ↑ "zet Cep". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=zet+Cep. 
  10. ↑ van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. http://www.aanda.org/articles/aa/full/2007/41/aa8357-07/aa8357-07.html. Vizier catalog entry
  11. ↑ 11.0 11.1 R. F., Griffin (April 2015). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 241: HR 1884, HD 174103, HD 182563, and HR 8442, with a note on zeta Cephei" (in en). The Observatory 135. ISSN 0029-7704. Bibcode: 2015Obs...135...71G. 
  12. ↑ Hekker (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. doi:10.1051/0004-6361:20078321. Bibcode: 2008A&A...480..215H. 
  13. ↑ Samus, N. N. et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S 1: 02025. Bibcode: 2009yCat....102025S. 

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