Zeta Aurigae

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ζ Aurigae
Auriga constellation map.svg
Red circle.svg
Location of ζ Aurigae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension  05h 02m 28.68739s[1]
Declination +41° 04′ 33.0200″[1]
Apparent magnitude (V) 3.751[2] (3.70 - 3.97[3])
Spectral type K5 II + B7 V[4]
U−B color index +0.374[2]
B−V color index +1.293[2]
R−I color index 0.87
Variable type Algol[3]
Radial velocity (Rv)+12.8[5] km/s
Proper motion (μ) RA: +9.45[1] mas/yr
Dec.: -20.71[1] mas/yr
Parallax (π)4.15 ± 0.29[1] mas
Distance790 ± 50 ly
(240 ± 20 pc)
Absolute magnitude (MV)−3.21[6]
Period (P)972.162 d
Semi-major axis (a)905 R
Eccentricity (e)0.3973 ± 0.0007
Inclination (i)87.0°
Periastron epoch (T)RJD 53039.9 ± 0.10
Argument of periastron (ω)
328.9° ± 0.13°
Semi-amplitude (K1)
23.17 ± 0.02 km/s
ζ Aur A
Mass4.94 ± 0.79[8] M
Luminosity3,254[8] L
Surface gravity (log g)1.33[9] cgs
Temperature3,920[9] K
Metallicity [Fe/H]–0.26[9] dex
Rotational velocity (v sin i)68[10] km/s
ζ Aur B
Mass4.8[7] M
Other designations
Saclateni, ζ Aur, 8 Aurigae, BD+40°1142, FK5 1137, HD 32068, HIP 23453, HR 1612, SAO 39966, WDS 05025+4105.[11]
Database references

Zeta Aurigae (ζ Aurigae, abbreviated Zeta Aur, ζ Aur), traditionally known as Sadatoni /sædəˈtni/[12] (among other names), is a binary star in the northern constellation of Auriga. Based upon parallax measurements made during the Hipparcos mission, this system is approximately 790 light-years (240 parsecs) distant from the sun, it has a combined apparent visual magnitude of 3.75,[2] which is bright enough to be seen with the naked eye.

The two components are designated Zeta Aurigae A (officially named Saclateni /sækləˈtni/, an old misspelling of "Sadatoni")[13] and B.


ζ Aurigae (Latinised to Zeta Aurigae) is the system's Bayer designation. The designations of the two components as ζ Aurigae A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[14]

The system bore the traditional names Haedus I (also Hoedus) and Sadatoni (rarely Saclateni), it was one of the two haedi (Latin: 'kids') of the she-goat Capella, the other being Haedus II, Eta Aurigae. The name Sadatoni is from the Arabic الساعد الثاني as-sācid aθ-θānī "the second arm (of the charioteer)". The rare traditional name Azaleh is shared (in the form Hassaleh) with Iota Aurigae.[15] In 2016, the IAU organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars; the WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[17] It approved the names Saclateni for the component Zeta Aurigae A and Haedus for Eta Aurigae on 30 June 2017 and they are both now so included in the List of IAU-approved Star Names.[13]

In Chinese, (Zhù), meaning Pillars, refers to an asterism consisting of Zeta Aurigae, Epsilon Aurigae, Eta Aurigae, Upsilon Aurigae, Nu Aurigae, Tau Aurigae, Chi Aurigae and 26 Aurigae.[18] Consequently, the Chinese name for Zeta Aurigae itself is 柱二 (Zhù èr, English: the Second Star of Pillars.)[19]


Zeta Aurigae is an eclipsing binary with the orbital plane being oriented close to the line of sight from the Earth; the inclination of this system is estimated as 87.0°.[7] As a result, an eclipse of one star by the other occurs during each orbit, causing the magnitude to decrease to +3.99. The pair have an orbital period of 972 days (2.66 years) and an eccentricity of 0.4.[7] The primary component, Zeta Aurigae A, has been categorized as a K-type bright giant or supergiant star, its companion, Zeta Aurigae B, is a B-type main sequence star of stellar classification B5 V or B7 V.[7][4]


  1. ^ a b c d e van Leeuwen, F. (November 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. ^ a b c d Kiyokawa, M. (1967), "Photoelectric Observation of Zeta Aurigae during the 1963-64 Eclipse", Publications of the Astronomical Society of Japan, 19: 209, Bibcode:1967PASJ...19..209K.
  3. ^ a b Samus, N. N.; Durlevich, O. V.; 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. Bibcode:2009yCat....102025S.
  4. ^ a b Shenavrin, V. I.; Taranova, O. G.; Nadzhip, A. E. (January 2011), "Search for and study of hot circumstellar dust envelopes", Astronomy Reports, 55 (1): 31–81, Bibcode:2011ARep...55...31S, doi:10.1134/S1063772911010070.
  5. ^ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  7. ^ a b c d e Eaton, Joel A.; Henry, Gregory W.; Odell, Andrew P. (June 2008), "Orbits and Pulsations of the Classical ζ Aurigae Binaries", The Astrophysical Journal, 679 (2): 1490–1498, arXiv:0802.2238, Bibcode:2008ApJ...679.1490E, doi:10.1086/587452.
  8. ^ a b Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
  9. ^ a b c McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants" (PDF), Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527. origin: STI
  10. ^ 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.
  11. ^ "zet Aur". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-08-19.
  12. ^ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. San Francisco, California. 48 (283).
  13. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  14. ^ Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  15. ^ "Al Kab". stars.astro.illinois.edu. Retrieved 2017-02-02.
  16. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  17. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  18. ^ ‹See Tfd›(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.
  19. ^ ‹See Tfd›(in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 29, 2011, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.

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