Nu Draconis

Nu Draconis (also known as ν Dra, ν Draconis, or traditionally as Kuma /ˈkjuːmə/) is a double star in the constellation Draco. The respective components are designated ν1 Draconis and ν2 Draconis. The second component is a spectroscopic binary star system.[14]

ν Draconis
Nu Draconis.jpg
ν Draconis in optical light
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
ν1 Dra
Right ascension 17h 32m 10.56856s[1]
Declination +55° 11′ 03.2739″[1]
Apparent magnitude (V) +4.88[2]
ν2 Dra
Right ascension 17h 32m 16.02464s[1]
Declination +55° 10′ 22.6504″[1]
Apparent magnitude (V) +4.88[2]
ν1 Dra
Spectral type A8Vm[3] (kA3hF0mF0[4])
U−B color index +0.03[2]
B−V color index +0.26[2]
ν2 Dra
Spectral type A4IVm[3] (kA3hF1mF0[4])
U−B color index +0.04[2]
B−V color index +0.27[2]
ν1 Dra
Radial velocity (Rv)–15.2[5] km/s
Proper motion (μ) RA: +147.39[1] mas/yr
Dec.: +54.31[1] mas/yr
Parallax (π)33.06 ± 0.15[1] mas
Distance98.7 ± 0.4 ly
(30.2 ± 0.1 pc)
ν2 Dra
Radial velocity (Rv)–16.0[5] km/s
Proper motion (μ) RA: +142.65[1] mas/yr
Dec.: +62.43[1] mas/yr
Parallax (π)32.80 ± 0.18[1] mas
Distance99.4 ± 0.5 ly
(30.5 ± 0.2 pc)
Primaryν2 Dra A
Companionν2 Dra B
Period (P)38.034 days
Eccentricity (e)0.03
Semi-amplitude (K1)
10.0 km/s
ν1 Dra
Mass1.85[7] M
Surface gravity (log g)4.2[8] cgs
Temperature7,533[8] K
Rotational velocity (v sin i)86[9] km/s
Age13.0[10] Myr
ν2 Dra
Mass1.61 + 0.24[7] M
Radius1.812[11] R
Surface gravity (log g)4.11[12] cgs
Temperature7,272[8] K
Rotational velocity (v sin i)68[9] km/s
Other designations
ν Draconis, ν Dra, Kuma
ν1 Dra: 24 Dra, BD+55 1944, FK5 655, HD 159541, HIP 85819, HR 6554, SAO 30447[13]
ν2 Dra: 25 Dra, BD+55 1945, FK5 657, HD 159560, HIP 85829, HR 6555, SAO 30450[14]
Database references
ν1 Dra
ν2 Dra

This star, along with β Dra (Rastaban), γ Dra (Eltanin), μ Dra (Erakis) and ξ Dra (Grumium) were Al ʽAwāïd, "the Mother Camels", which was later known as the Quinque Dromedarii.[15]

In Chinese, 天棓 (Tiān Bàng), meaning Celestial Flail, refers to an asterism consisting of ν Draconis, ξ Draconis, β Draconis, γ Draconis and ι Herculis.[16] Consequently, the Chinese name for ν Draconis itself is 天棓二 (Tiān Bàng èr, English: the Second Star of Celestial Flail.)[17]

The two stars of the visual binary are considered to be a common proper motion pair on the basis of their very similar parallaxes, radial velocities, and proper motions, although no orbital motion can be observed.[18]

ν1 Draconis is an Am star, a slowly-rotating chemically peculiar star with abnormally strong metallic absorption lines in its spectrum. Its spectral type of kA3hF0mF0 means that it would have a spectral class of A3 if determined solely from its calcium K lines, F0 if determined from its hydrogen lines, and F0 if determined from other metallic spectral lines.[4]

ν2 Draconis is a spectroscopic binary with a period of 38 days. The two stars are separated by 0.267 au on average, and they have an almost circular orbit with an eccentricity of 0.03.[19][6] The primary is also an Am star, while the secondary has a low mass and luminosity and is only inferred from the orbital movement of the more massive star.[7]


  1. ^ a b c d e f g h i j 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. ^ a b c d e f 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. ^ a b Chen, P. S; Liu, J. Y; Shan, H. G (2017). "A New Photometric Study of Ap and Am Stars in the Infrared". The Astronomical Journal. 153 (5): 218. Bibcode:2017AJ....153..218C. doi:10.3847/1538-3881/aa679a.
  4. ^ a b c Abt, Helmut A; Morrell, Nidia I (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
  5. ^ a b Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W.
  6. ^ a b Margoni, R; Munari, U; Stagni, R (1992). "Spectroscopic orbits of AM stars. I - Seven field stars". Astronomy and Astrophysics Supplement Series. 93: 545. Bibcode:1992A&AS...93..545M.
  7. ^ a b c A.Tokovinin. "Multiple Star Catalog". Retrieved 2018-04-24.
  8. ^ a b c d Soubiran, Caroline; Le Campion, Jean-François; Brouillet, Nathalie; Chemin, Laurent (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics. 591: A118. arXiv:1605.07384. Bibcode:2016A&A...591A.118S. doi:10.1051/0004-6361/201628497. S2CID 119258214.
  9. ^ 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 (3): 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943, S2CID 14070763
  10. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (2011). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. S2CID 118629873. Vizier catalog entry
  11. ^ Masana, E; Jordi, C; Ribas, I (2006). "Effective temperature scale and bolometric corrections from 2MASS photometry". Astronomy & Astrophysics. 450 (2): 735. arXiv:astro-ph/0601049. Bibcode:2006A&A...450..735M. doi:10.1051/0004-6361:20054021. S2CID 15278668.
  12. ^ Stateva, I.; Belcheva, M.; Iliev, I. Kh.; Budaj, J.; Barzova, I.S. (April 2008). "Chemical abundances study of three Am stars HD155375, HD159560 and HD196544". Contributions of the Astronomical Observatory Skalnaté Pleso. 38 (2): 455–456. Bibcode:2008CoSka..38..455S.
  13. ^ "24 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-06-04.
  14. ^ a b "25 Dra". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-06-04.
  15. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 207, ISBN 978-0-486-21079-7, retrieved 2010-12-12
  16. ^ (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.
  17. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2011-01-29 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. ^ Lépine, Sébastien; Bongiorno, Bethany (2007). "New Distant Companions to Known Nearby Stars. II. Faint Companions of Hipparcos Stars and the Frequency of Wide Binary Systems". The Astronomical Journal. 133 (3): 889–905. arXiv:astro-ph/0610605. Bibcode:2007AJ....133..889L. doi:10.1086/510333. S2CID 16800796.
  19. ^ Rodriguez, David R; Duchêne, Gaspard; Tom, Henry; Kennedy, Grant M; Matthews, Brenda; Greaves, Jane; Butner, Harold (2015). "Stellar multiplicity and debris discs: An unbiased sample". Monthly Notices of the Royal Astronomical Society. 449 (3): 3160. arXiv:1503.01320. Bibcode:2015MNRAS.449.3160R. doi:10.1093/mnras/stv483. S2CID 119237891.

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