26 Draconis

From the Science Archives, the open-project database of science information
Jump to navigation Jump to search
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
Distance46.3 ± 0.2 ly
(14.19 ± 0.07 pc)
Absolute magnitude (MV)4.58±0.011[5]
Primary26 Dra A
Companion26 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)
Mass1.30/0.83[7] M
Surface gravity (log g)4.50[8] cgs
Temperature6,000[8] K
Metallicity [Fe/H]-0.18[9] dex
Rotational velocity (v sin i)10[10] km/s
Age8.4–11.5[9] Gyr
Other designations
BD+61 1678, WDS J17350+6153, CCDM J17351+6152
AB: 26 Dra, HD 160269, HIP 86036, HR 6573, LHS 3305, LTT 15223, SAO 17546[11]
C: HIP 86037, LTT 15224
Database references

26 Draconis is a triple star system[12] 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.[7] 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.[9]

The third component, GJ 685, is a red dwarf spectral classification of M1V. As of 1970, this star is separated by 737.9 arc seconds from the AB pair and they share a common proper motion.[13]

The space velocity components of 26 Draconis are U = +36.5, V = −4.3 and W = −21.8 km/s.[14] 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.[15] This system may be a member of the Ursa Major moving group.[16]


  1. 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (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. 2.0 2.1 2.2 Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–4.
  3. 3.0 3.1 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. Lua error in Module:Citation/CS1 at line 886: bad argument #1 to 'sub' (string expected, got table).
  5. Park, Sunkyung et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal 146 (4): 73, arXiv:1307.0592, Bibcode 2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73.
  6. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  7. 7.0 7.1 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.
  8. 8.0 8.1 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.
  9. 9.0 9.1 9.2 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:0808.3414. Bibcode 2008ApJ...687..566M. doi:10.1086/591638.
  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. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  12. 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.
  13. 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. arXiv:astro-ph/0610605. Bibcode 2007AJ....133..889L. doi:10.1086/510333.
  14. 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.
  15. 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:0811.3982. Bibcode 2009A&A...501..941H. doi:10.1051/0004-6361/200811191.
  16. 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:0907.3677. Bibcode 2009MNRAS.397..757G. doi:10.1111/j.1365-2966.2009.15048.x.

Add your comment
The Science Archives welcomes all comments. If you do not want to be anonymous, register or log in. It is free.

As a reminder, article comments are only for discussions on how to improve the article. Please direct other comments to a user's talk page. Please be formal and do not use excessive uppercase. Please be advised you may receive an automatic block if you break the article comments policy. For information regarding what is acceptable/not acceptable in article comments, please message Icons-flag-ru.png Joey (talk), Natalia (talk), Icons-flag-fr.png ynoss (talk), or Icons-flag-ca.png Daniel (older account/talk).