Zeta Capricorni

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Zeta Capricorni
Diagram showing star positions and boundaries of the Hydra constellation and its surroundings
Cercle rouge 100%.svg

Location of ζ Capricorni (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Capricornus
Right ascension 21h 26m 40.02634s[1]
Declination −22° 24′ 40.8042″[1]
Apparent magnitude (V) 3.74[2]
Spectral type G8IIIp / DA2.2[3]
U−B color index +0.57[4]
B−V color index +0.99[4]
Radial velocity (Rv) 2.10[2] km/s
Proper motion (μ) RA: -2.23[1] mas/yr
Dec.: 18.10[1] mas/yr
Parallax (π) 8.46 ± 0.21[1] mas
Distance 386 ± 10 ly
(118 ± 3 pc)
Absolute magnitude (MV) 0.88
Primary ζ Cap A
Companion ζ Cap B
Period (P) 2378.2 d
Semi-major axis (a) 8.56 ± 4.3 mas
Eccentricity (e) 0.2821
Inclination (i) 111.7 ± 20.7°
Longitude of the node (Ω) 190.7 ± 50.0°
Periastron epoch (T) JD 2445996
Argument of periastron (ω)
233.8 ± 19.8°
ζ Cap A
Mass 3.99 ± 0.12[6] M
Radius ~29[7] R
Luminosity 490[6] L
Surface gravity (log g) 1.48 ± 0.16[8] cgs
Temperature 5397 ± 82[8] K
Metallicity [Fe/H] −0.14 ± 0.10[8] dex
ζ Cap B
Mass 1[3] M
Temperature 23000[3] K
Other designations
ζ Cap, 34 Cap, CD-22° 15388, HD 204075, HIP 105881, SAO 190341, HR 8204, GC 30020, CCDM J21267-2225AB, WDS J21267-2225AB
Database references

Zeta Capricorni, (ζ Cap, ζ Capricorni), is a fourth-magnitude star in the constellation Capricornus. ζ Capricorni is a binary star, with the primary component ζ Capricorni A being a yellow G-type giant with an apparent magnitude of +3.77. It is considered one of the prototypical examples of a Barium star, properties of which include overabundances of carbon molecules (such as C2) and s-process elements. Zeta Capricorni has an overabundance of the s-process element praseodymium.

Its companion, ζ Capricorni B is a hydrogen-rich white dwarf. It is about as massive as the Sun, and its temperature is 23,000 K.[3]

The ζ Capricorni binary system is approximately 390 light years from Earth, based on its parallax.[1]

Chinese Name[edit]

In Chinese, 十二國 (Shíer Guó), meaning Twelve States, refers to an asterism which represents twelve ancient states in the Spring and Autumn period and the Warring States period, consisting of ζ Capricorni, φ Capricorni, ι Capricorni, 38 Capricorni, 35 Capricorni, 36 Capricorni, χ Capricorni, θ Capricorni, 30 Capricorni, 33 Capricorni, 19 Capricorni, 26 Capricorni, 27 Capricorni, 20 Capricorni, η Capricorni and 21 Capricorni.[9] Consequently, ζ Capricorni itself represents the state of Yan ().,[10] together with ν Ophiuchi in Left Wall of Heavenly Market Enclosure (asterism).[11]


  1. ^ a b c d e f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ a b "zet Cap". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 28 December 2016. 
  3. ^ a b c d Holberg, J. B.; Oswalt, T. D.; Sion, E. M.; Barstow, M. A.; Burleigh, M. R. (2013). "Where are all the Sirius-like binary systems?". Monthly Notices of the Royal Astronomical Society. 435 (3): 2077. Bibcode:2013MNRAS.435.2077H. arXiv:1307.8047Freely accessible. doi:10.1093/mnras/stt1433. 
  4. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV data. Bibcode:1986EgUBV........0M. 
  5. ^ Pourbaix, D. (2000). "Re-processing the Hipparcos Transit Data and Intermediate Astrometric Data of spectroscopic binaries. I. Ba, CH and Tc-poor S stars". Astronomy and Astrophysics Supplement. 145: 161–183. Bibcode:2000A&AS..145..161P. arXiv:astro-ph/0006175Freely accessible. doi:10.1051/aas:2000346. 
  6. ^ a b Hohle, M.M.; Neuhäuser, R.; Schutz, B.F. (2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349. Bibcode:2010AN....331..349H. arXiv:1003.2335Freely accessible. doi:10.1002/asna.200911355. 
  7. ^ "ZETA CAP (Zeta Capricorni)". Retrieved 30 December 2016. 
  8. ^ a b c Prugniel, Ph.; et al. (July 2011). "The atmospheric parameters and spectral interpolator for the MILES stars". Astronomy & Astrophysics. 531: A165. Bibcode:2011A&A...531A.165P. arXiv:1104.4952Freely accessible. doi:10.1051/0004-6361/201116769. 
  9. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  10. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Capricornus
  11. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 23 日