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Zeta Draconis (ζ Dra, ζ Draconis) is the Bayer designation for a star in the northern circumpolar constellation of Draco. It shares the Arabic name Al dhi'bah ('the hyenas') with several other stars in the constellation,[9] and shares the name Al dhibain with Eta Draconis.[10] It is known as Nodus III (Third Knot, the knot being a loop in the tail of Draco).[11] With an apparent visual magnitude of +3.17,[2] it is the fifth-brightest member of this generally faint constellation. The distance to Zeta Draconis has been measured using the parallax technique, yielding an estimate of roughly 330 light-years (100 parsecs) away.[1]

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

Location of ζ Draconis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 17h 08m 47.19596s[1]
Declination +65° 42′ 52.8634″[1]
Apparent magnitude (V) +3.17[2]
Spectral type B6 III[3]
U−B color index –0.43[2]
B−V color index –0.11[2]
Radial velocity (Rv) –17[4] km/s
Proper motion (μ) RA: –20.43[1] mas/yr
Dec.: +19.61[1] mas/yr
Parallax (π) 9.93 ± 0.35[1] mas
Distance 330 ± 10 ly
(101 ± 4 pc)
Absolute magnitude (MV) −1.88[5]
Mass 3.5[6] M
Radius 2.3[6] R
Luminosity 148[6] L
Surface gravity (log g) 4.24[3] cgs
Temperature 13,397[3] K
Metallicity [Fe/H] –0.95[3] dex
Rotational velocity (v sin i) 55[7] km/s
Other designations
22 Draconis, BD+65 1170, FK5 639, HD 155763, HIP 83895, HR 6396, SAO 17365.[8]
Database references

Zeta Draconis is mentioned in Hindu mythology as Tara who was a celestial goddess married to Lord Brihaspati. A divine epic was played out in the night sky when Lord Chandra, the moon, lusted after and abducted Tara, the blue pole star of Brihaspati, the planet Jupiter. By the completion of the epic Tara gives birth to Lord Budha, or Mercury.[citation needed]

In Chinese, 紫微左垣 (Zǐ Wēi Zuǒ Yuán), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of ζ Draconis, ι Draconis, η Draconis, θ Draconis, υ Draconis, 73 Draconis, γ Cephei and 23 Cassiopeiae.[12] Consequently, ζ Draconis itself is known as 紫微左垣四 (Zǐ Wēi Zuǒ Yuán sì, English: the Fourth Star of Left Wall of Purple Forbidden Enclosure.),[13] representing 上弼 (Shǎngbì), meaning The First Minister.[14] 上弼 (Shǎngbì) is westernized into Shang Pih by R.H. Allen with meaning "the Higher Minister".[15]

Zeta Draconis is a giant star with a stellar classification of B6 III.[3] Compared to the Sun, this star is about 2.5 times larger, 3.5 times more massive, and is radiating 148 times as much luminosity.[6] This energy is being emitted from the star's outer envelope at an effective temperature of nearly 13,400 K.[3] The azimuthal rotation velocity along the equator is at least 55 km/s.[7]

The north ecliptic pole is located at right ascension 18h and declination +66.5°.[16] This is located roughly midway between Delta Draconis and Zeta Draconis.[17] The north ecliptic pole almost coincides with the south celestial pole of Venus; Zeta Draconis is also the north pole star of Jupiter.[18]


  1. ^ a b c d e f 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 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b c d e f Cenarro, A. J.; et al. (2007), "Medium-resolution Isaac Newton Telescope Library of Empirical Spectra – II. The Stellar Atmospheric Parameters", Monthly Notices of the Royal Astronomical Society, 374 (2): 664–690, arXiv:astro-ph/0611618 , Bibcode:2007MNRAS.374..664C, doi:10.1111/j.1365-2966.2006.11196.x. 
  4. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E. 
  5. ^ Huang, W.; et al. (2012), "A catalogue of Paschen-line profiles in standard stars", Astronomy & Astrophysics, 547: A62, arXiv:1210.7893 , Bibcode:2012A&A...547A..62H, doi:10.1051/0004-6361/201219804. 
  6. ^ a b c d Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M. 
  7. ^ a b Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255 , Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  8. ^ "Zet Dra", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2009-10-10. 
  9. ^ Allen, Richard Hinckley (1899), Star-names and their meanings, New York: G. E. Stechert, p. 210. 
  10. ^ Rumrill, H. B. (June 1936), "Star Name Pronunciation", Publications of the Astronomical Society of the Pacific, 48 (283): 139–154, Bibcode:1936PASP...48..139R, doi:10.1086/124681. 
  11. ^ Kaler, Jim, "Al Dhibain ("The Posterior")", Stars, University of Illinois, retrieved 2009-10-12. 
  12. ^ (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.
  13. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 10 日
  14. ^ (in Chinese) English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Archived August 10, 2010, at the Wayback Machine., Hong Kong Space Museum. Accessed on line November 23, 2010.
  15. ^ Star Name - R.H. Allen p. 210
  16. ^ Chartrand, Mark R.; Wimmer, Helmut K. (2001), Night Sky: A Guide To Field Identification, Macmillan, p. 12, ISBN 1-58238-126-7. 
  17. ^ Young, Charles Augustus (1919), Anne Sewell Young, ed., The Elements of Astronomy: a Textbook, Ginn and company, p. 69, retrieved 2009-10-12. 
  18. ^ Sharrah, Paul C. (1975). "Pole Stars of Other Planets" (PDF). Arkansas Academy of Sciences Proceedings. XXIX: 62–63.