Chi Draconis

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χ Draconis
Draco constellation map.svg
Red circle.svg
Location of χ Draconis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Draco
Right ascension 18h 21m 03.38255s[1]
Declination +72° 43′ 58.2518″[1]
Apparent magnitude (V) 3.570[2] (3.68 / 5.67)
Spectral type F7V[3] / K0V
U−B color index -0.06
B−V color index 0.49
Variable type Suspected
Radial velocity (Rv)+32.4[2] km/s
Proper motion (μ) RA: 531.21[1] mas/yr
Dec.: -349.71[1] mas/yr
Parallax (π)124.11 ± 0.87[1] mas
Distance26.3 ± 0.2 ly
(8.06 ± 0.06 pc)
Absolute magnitude (MV)4.04[2]
CompanionChi Draconis B
Period (P)0.7680599 ± 0.000061 yr
Semi-major axis (a)0.1244 ± 0.0011″
Eccentricity (e)0.428 ± 0.012
Inclination (i)74.42 ± 0.58°
Longitude of the node (Ω)230.30 ± 0.51°
Periastron epoch (T)1984.8324 ± 0.0026
Argument of periastron (ω)
119.3 ± 1.1°
χ Dra A
Mass1.029 ± 0.026[5] M
Radius1.20 ± 0.09[5] R
Diameter1.20 ± 0.09[5] D
Luminosity1.86[5] L
Temperature6,150 ± 150[5] K
Metallicity [Fe/H]−0.41[2] dex
Rotational velocity (v sin i)11[6] km/s
Age5.3[2] Gyr
χ Dra B
Mass0.748 ± 0.017[5] M
Radius0.73 ± 0.11[5] R
Luminosity0.29[5] L
Temperature4,940 ± 200[5] K
Other designations
χ Dra, 44 Dra, BD+72° 839, FK5 695, Gl 713, HD 170153, HIP 89937, HR 6927, LHS 3379, LTT 15438, SAO 9087.[3]
Database references

Chi Draconis (χ Dra, χ Draconis, Chi Draconis) is a star system in the constellation Draco.


The first companion is a yellow-white (class F) fourth-magnitude star with a mass approximately equal to that of the sun, but it is nearly twice as luminous. The second companion is an orange (class K) sixth-magnitude star, that is less massive and of lesser luminosity than the sun. In 1898 this system was reported to be a spectroscopic binary system, with an orbital period of 280.55 days. The two stars have an average separation of nearly an astronomical unit, which would disrupt the orbit of any Earth-like planet that was close enough to the primary to support liquid water. The two stars have less than half the abundance of heavy elements as the Sun and are approximately a billion years older.[2]

See also[edit]


  1. 1.0 1.1 1.2 1.3 1.4 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
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Nordström, B. et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14 000 F and G dwarfs", Astronomy and Astrophysics 418: 989–1019, arXiv:astro-ph/0405198, Bibcode 2004A&A...418..989N, doi:10.1051/0004-6361:20035959
  3. 3.0 3.1 "chi Dra -- Star in double system", SIMBAD (Centre de Données astronomiques de Strasbourg),, retrieved 2011-10-15
  4. Farrington, C. D. et al. (June 2010), "Separated Fringe Packet Observations with the CHARA Array. I. Methods and New Orbits for χ Draconis, HD 184467, and HD 198084", The Astronomical Journal 139 (6): 2308–2318, Bibcode 2010AJ....139.2308F, doi:10.1088/0004-6256/139/6/2308
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Torres, G.; Andersen, J.; Giménez, A., "Accurate masses and radii of normal stars: modern results and applications", The Astronomy and Astrophysics Review 18 (1-2): 67–126, arXiv:0908.2624, Bibcode 2010A&ARv..18...67T, doi:10.1007/s00159-009-0025-1 See p. 56, entry #15.
  6. Monin, D. N.; Fabrika, S. N.; Valyavin, G. G. (2002). "Magnetic survey of bright northern main sequence stars". Astronomy & Astrophysics 396 (1): 131–141. Bibcode 2002A&A...396..131M. doi:10.1051/0004-6361:20021425.

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