26 Draconis

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26 Draconis
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 17h 34m 59.59363s[1]
Declination +61° 52′ 28.4006″[1]
Apparent magnitude (V) 5.236[2]
Spectral type G0Va (F9V + K3V)[3]
U−B color index +0.100[2]
B−V color index +0.595[2]
Radial velocity (Rv) –12.7[4] km/s
Proper motion (μ) RA: 277.02[1] mas/yr
Dec.: –524.88[1] mas/yr
Parallax (π) 70.47 ± 0.37[1] mas
Distance 46.3 ± 0.2 ly
(14.19 ± 0.07 pc)
Primary 26 Dra A
Companion 26 Dra B
Period (P) 76.1 yr
Semi-major axis (a) 1.53"
Eccentricity (e) 0.18
Inclination (i) 104°
Longitude of the node (Ω) 151°
Periastron epoch (T) 1947
Argument of periastron (ω)
Mass 1.30/0.83[6] M
Surface gravity (log g) 4.50[7] cgs
Temperature 6,000[7] K
Metallicity [Fe/H] -0.18[8] dex
Rotational velocity (v sin i) 10[9] km/s
Age 8.4–11.5[8] Gyr
Other designations
26 Dra, BD+61 1678, HD 160269, HIP 86036, HR 6573, LHS 3305, LTT 15223, SAO 17546.[10]
Database references

26 Draconis is a triple star system[11] in the constellation Draco, located 46 light years from the Sun. Two of the system components, A and B, form a spectroscopic binary that completes an orbit every 76 years. The composite spectral classification of the AB pair is G0V, which decomposes to individual spectral types F9V and K3V.[3] A 1962 study estimated the masses of these two stars as 1.30 and 0.83 times the mass of the Sun, respectively.[6] The stars are considered moderately metal-poor compared to the Sun, which means they have a lower proportion of elements other than hydrogen or helium.[8]

The third component, GJ 685, is a red dwarf spectral classification of M1V. As of 1970, this star is separated by 12.2 arc seconds with the AB pair and they share a common proper motion.[8] The space velocity components of 26 Draconis are U = +36.5, V = −4.3 and W = −21.8 km/s.[12] This system is on an orbit through the Milky Way galaxy that has an eccentricity of 0.14, taking it as close as 23.1 kly (7.08 kpc) and as far as 30.4 kly (9.32 kpc) from the galactic core. The inclination of this orbit carries the star system as much as 0.75 kly (0.23 kpc) above the plane of the galactic disk.[13] This system may be a member of the Ursa Major moving group.[14]


  1. ^ a b c d e van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4. 
  3. ^ a b Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879 
  4. ^ Wilson, Ralph Elmer (1953). General Catalogue of Stellar Radial Velocities. Washington: Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W. 
  5. ^ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 25 March 2017. 
  6. ^ a b Upgren, A. R. (October 1962). "Parallax and orbital motion of the triple system 26 Draconis from photographs taken with the Sproul 24-inch refractor". Astronomical Journal. 67: 539–543. Bibcode:1962AJ.....67..539U. doi:10.1086/108760. 
  7. ^ a b Luck, R. Earle; Heiter, Ulrike (June 2006). "Dwarfs in the Local Region". The Astronomical Journal. 131 (6): 3069–3092. Bibcode:2006AJ....131.3069L. doi:10.1086/504080. 
  8. ^ a b c d Makarov, V. V.; Zacharias, N.; Hennessy, G. S. (November 2008). "Common Proper Motion Companions to Nearby Stars: Ages and Evolution". The Astrophysical Journal. 687 (1): 566–578. arXiv:0808.3414Freely accessible. Bibcode:2008ApJ...687..566M. doi:10.1086/591638. 
  9. ^ 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. 
  10. ^ "HD 160269". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-02-17. 
  11. ^ Greaves, J. S.; Wyatt, M. C. (November 2003). "Some anomalies in the occurrence of debris discs around main-sequence A and G stars". Monthly Notices of the Royal Astronomical Society. 345 (4): 1212–1222. Bibcode:2003MNRAS.345.1212G. doi:10.1046/j.1365-2966.2003.07037.x. 
  12. ^ Soderblom, David R.; Mayor, Michel (January 1993). "Stellar kinematic groups. I - The Ursa Major group". Astronomical Journal. 105 (1): 226–249. Bibcode:1993AJ....105..226S. doi:10.1086/116422. 
  13. ^ Holmberg, J.; Nordström, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics. 501 (3): 941–947. arXiv:0811.3982Freely accessible. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191. 
  14. ^ Greaves, J. S.; Wyatt, M. C.; Bryden, G. (August 2009). "Debris discs around nearby solar analogues". Monthly Notices of the Royal Astronomical Society. 397 (2): 757–762(6). arXiv:0907.3677Freely accessible. Bibcode:2009MNRAS.397..757G. doi:10.1111/j.1365-2966.2009.15048.x.