Zeta Draconis

Zeta Draconis (ζ Draconis, abbreviated Zet Dra, ζ Dra) is a binary star in the northern circumpolar constellation of Draco. With an apparent visual magnitude of +3.17,[2] it is the fifth-brightest member of this generally faint constellation. Its distance from the Sun has been measured using the parallax technique, yielding an estimate of roughly 330 light-years (100 parsecs).[1]

ζ Draconis
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]
Characteristics
Spectral type B6 III[3]
U−B color index –0.43[2]
B−V color index –0.11[2]
Astrometry
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
Distance330 ± 10 ly
(101 ± 4 pc)
Absolute magnitude (MV)−1.88[5]
Details
Mass3.5[6] M☉
Radius2.3[6] R☉
Luminosity148[6] L☉
Surface gravity (log g)4.24[3] cgs
Temperature13,397[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, WDS 17088+6543.[8]
Database references
SIMBADdata

The two components are designated Zeta Draconis A (formally named Aldhibah /ælˈdaɪbə/, after the traditional name of the system)[9] and B.

Nomenclature

ζ Draconis (Latinised to Zeta Draconis) is the system's Bayer designation. The designations of the two components as Zeta Draconis A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[10]

Zeta Draconis has the old Arabic name الذئب al-dhiʼb "the wolf", given in its feminine form "Al Dhiʼbah" (ذئبة) in Allen (1899) (though he mistranslated it as plural "hyenas", which would be الضباع al-ḍibāʽ).[11] It shares the dual form of the name, الذئبين al-dhiʼbayn, with Eta Draconis.[12] It is also known as Nodus III (Third Knot, the knot being a loop in the tail of Draco).[13]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[15] It approved the name Aldhibah for the component Zeta Draconis A on 5 September 2017. It also approved the name Athebyne for Eta Draconis A on the same date. Both are now so included in the List of IAU-approved Star Names.[9]

Zeta Draconis is mentioned in Hindu mythology as Tara who was a celestial goddess married to Lord Brhaspati. 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 Brhaspati, the planet Jupiter. By the completion of the epic Tara gives birth to Lord Budha, or Mercury.[16]

In Chinese, 紫微左垣 (Zǐ Wēi Zuǒ Yuán), meaning Left Wall of Purple Forbidden Enclosure, refers to an asterism consisting of Zeta Draconis, Iota Draconis, Eta Draconis, Theta Draconis, Upsilon Draconis, 73 Draconis, Gamma Cephei and 23 Cassiopeiae.[17] Consequently, the Chinese name for Zeta Draconis itself is 紫微左垣四 (Zǐ Wēi Zuǒ Yuán sì, English: the Fourth Star of Left Wall of Purple Forbidden Enclosure),[18] representing 上弼 (Shǎngbì), meaning The First Minister.[19] 上弼 (Shǎngbì) is westernized into Shang Pih by R.H. Allen with meaning "the Higher Minister".[20]

Properties

Zeta Draconis A 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°.[21] This is located roughly midway between Delta Draconis and Zeta Draconis.[22] The north ecliptic pole almost coincides with the south celestial pole of Venus; Zeta Draconis is also the north pole star of Jupiter.[23]

References
  1. 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, S2CID 18759600.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. 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, S2CID 119428437.
  4. Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), 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, S2CID 119286159.
  6. 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. 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, S2CID 14070763.
  8. "Zet Dra", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2009-10-10.
  9. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  10. 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].
  11. Allen, Richard Hinckley (1899), Star-names and their meanings, New York: G. E. Stechert, p. 210.
  12. 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.
  13. Kaler, Jim, "Al Dhibain ("The Posterior")", Stars, University of Illinois, retrieved 2009-10-12.
  14. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  16. George Mason Williams (2003). Handbook of Hindu Mythology. ABC-CLIO. p. 91. ISBN 1576071065. Retrieved 17 July 2015.
  17. (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.
  18. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 10 日
  19. (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.
  20. Star Name - R.H. Allen p. 210
  21. Chartrand, Mark R.; Wimmer, Helmut K. (2001), Night Sky: A Guide To Field Identification, Macmillan, p. 12, ISBN 1-58238-126-7.
  22. Young, Charles Augustus (1919), Anne Sewell Young (ed.), The Elements of Astronomy: a Textbook, Ginn and company, p. 69, retrieved 2009-10-12.
  23. Sharrah, Paul C. (1975). "Pole Stars of Other Planets" (PDF). Arkansas Academy of Sciences Proceedings. XXIX: 62–63.
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