26 Draconis

Last updated
26 Draconis
Observation data
Epoch J2000       Equinox J2000
Constellation Draco
AB
Right ascension 17h 34m 59.62474s [1]
Declination +61° 52′ 28.2418″ [1]
Apparent magnitude  (V)5.236 [2]
C
Right ascension 17h 35m 34.47852s [3]
Declination +61° 40′ 53.6281″ [3]
Apparent magnitude  (V)9.97 [4]
Characteristics
AB
Spectral type G0Va (F9V + K3V) [5]
U−B color index +0.100 [2]
B−V color index +0.595 [2]
C
Spectral type M0.5V [4]
B−V color index +1.48 [4]
Astrometry
AB
Radial velocity (Rv)−15.72±0.33 [1] km/s
Proper motion (μ)RA: 236.247 mas/yr [1]
Dec.: -466.111 mas/yr [1]
Parallax (π)69.2832±0.2004  mas [1]
Distance 47.1 ± 0.1  ly
(14.43 ± 0.04  pc)
Absolute magnitude  (MV)4.58±0.011 [6]
C
Radial velocity (Rv)−15.53±0.16 [3] km/s
Proper motion (μ)RA: 261.923  mas/yr [3]
Dec.: -514.499  mas/yr [3]
Parallax (π)69.8921 ± 0.0153  mas [3]
Distance 46.67 ± 0.01  ly
(14.308 ± 0.003  pc)
Orbit [7]
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)
(secondary)		307°
Details
AB
Mass 1.30/0.83 [8]   M☉
Surface gravity (log g)4.50 [9]   cgs
Temperature 6,000 [9]   K
Metallicity [Fe/H]-0.18 [10]   dex
Rotational velocity (v sin i)10 [11]  km/s
Age 8.4–11.5 [10]   Gyr
C
Mass 0.55±0.06 [4]   M☉
Radius 0.54±0.05 [4]   R☉
Surface gravity (log g)4.72±0.05 [4]   cgs
Temperature 3816±69 [4]   K
Metallicity [Fe/H]−0.15±0.09 [4]   dex
Rotation 18.15+0.15
−0.16  d [4]
Rotational velocity (v sin i)1.33±0.42 [4]  km/s
Other designations
ADS 10660, CCDM J17351+6152, WDS J17350+6153
AB: 26 Dra , BD+61 1678, GJ 684, HD 160269, HIP 86036, HR 6573, SAO 17546, LHS 3305, LTT 15223 [12]
C: GJ 685, HIP 86087, G 226-66, LHS 3306, LTT 15224 [13]
Database references
SIMBAD A
B
C

26 Draconis is a triple star system [14] in the constellation Draco, located 47 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. [5] A 1962 study estimated the masses of these two stars as 1.30 and 0.83 times the mass of the Sun, respectively. [8] 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. [10]

The space velocity components of 26 Draconis are U = +36.5, V = −4.3 and W = −21.8 km/s. [15] 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. [16] This system may be a member of the Ursa Major moving group. [17]

Gliese 685

The third component, GJ 685, is a red dwarf with spectral classification of M0V. As of 1970, this star is separated by 737.9 arc seconds from the AB pair and they share a common proper motion. [18] The star GJ 685 has one known planet in orbit that was detected by radial velocity. [4]

The Gliese 685 planetary system [4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b≥9.0+1.7
−1.8  M🜨 		0.1344+0.0052
−0.0051		24.160+0.061
−0.047		———

References

  1. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 3 Oja, T. (1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4, Bibcode:1986A&AS...65..405O.
  3. 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 Pinamonti, M.; Sozzetti, A.; Giacobbe, P.; et al. (May 2019). "The HADES RV programme with HARPS-N at TNG. XI. GJ 685 b: a warm super-Earth around an active M dwarf". Astronomy & Astrophysics . 625: A126. arXiv: 1903.11853 . Bibcode:2019A&A...625A.126P. doi:10.1051/0004-6361/201834969. S2CID   85542910.
  5. 1 2 Edwards, T. W. (April 1976), "MK classification for visual binary components", Astronomical Journal, 81: 245–249, Bibcode:1976AJ.....81..245E, doi:10.1086/111879
  6. ↑ 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, S2CID   119187733.
  7. ↑ "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Archived from the original on 30 April 2017. Retrieved 25 March 2017.
  8. 1 2 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 .
  9. 1 2 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 .
  10. 1 2 3 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. S2CID   17811620.
  11. ↑ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1): 1. Bibcode:1970CoAsi.239....1B.
  12. ↑ "HD 160269". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2010-02-17.
  13. ↑ "GJ 685". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 18 March 2025.
  14. ↑ 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 .
  15. ↑ 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 .
  16. ↑ 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. S2CID   118577511.
  17. ↑ 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 . S2CID   17758971.
  18. ↑ Lépine, Sébastien; Bongiorno, Bethany (2007). "New Distant Companions to Known Nearby Stars. II. Faint Companions of HipparcosStars 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.
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