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]
Characteristics
Spectral type F7V / K0V [3]
U−B color index −0.06 [4]
B−V color index +0.49 [4]
Variable type Suspected [5]
Astrometry
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)120.05±0.15  mas [3]
Distance 27.17 ± 0.03  ly
(8.33 ± 0.01  pc)
Absolute magnitude  (MV)4.04 [2]
Orbit [6]
Primaryχ Dra Aa
Companionχ Dra Ab
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)1,984.8324±0.0026
Argument of periastron (ω)
(secondary)		119.3±1.1°
Details
χ Dra Aa
Mass 1.029±0.026 [3]   M☉
Radius 1.20±0.09 [3]   R☉
Luminosity 1.86 [3]   L☉
Temperature 6,150±150 [3]   K
Metallicity [Fe/H]−0.41 [2]   dex
Rotational velocity (v sin i)11 [7]  km/s
Age 5.3 [2]   Gyr
χ Dra Ab
Mass 0.748±0.017 [3]   M☉
Radius 0.73±0.11 [3]   R☉
Luminosity0.29 [3]   L☉
Temperature 4,940±200 [3]   K
Other designations
χ Dra, 44 Dra, NSV 10749, BD+72°839, FK5 695, GJ 713, HD 170153, HIP 89937, HR 6927, SAO 9087, LHS 3379, LTT 15438 [8]
Database references
SIMBAD data

Chi Draconis is a magnitude 3.6 binary star in the constellation Draco. At a distance of 27 light-years, it is one of the 200 or so closest stars. [9]

Contents

Nomenclature

Chi Draconis (Latinized from χ Draconis, abbreviated χ Dra, Chi Dra) is the star's Bayer designation. It also has the Flamsteed designation 44 Draconis.

In a 1971 NASA memorandum, this star was listed with the name Alahakan. [10] According to R. H. Allen's Star Names , Al ʽAuhaḳān, meaning "the two black bulls, or ravens", was an Arabic name for χ and ψ Draconis, among other stars in Draco. [11]

In Chinese astronomy, this star is identified as Yùnǚsì (御女四), the fourth star of the asterism Yùnǚ (御女, Maids-in-waiting; also 31 Leonis). [12] Alternatively, it may be Zhùshǐ (柱史, Official of Royal Archives), [13] usually identified as φ Draconis. [12] R. H. Allen (using a now outdated romanization of Chinese) said it was Kwei She. [11]

Binary system

kh Draconis in optical light Chi Draconis.jpg
χ Draconis in optical light

χ Draconis is a spectroscopic binary which has been resolved using speckle interferometry. [4] The primary is an F7 main sequence star. The spectral type of the companion cannot be determined directly with any accuracy, but is known to be between G8 and K2 and is assumed to be K0. The properties of the secondary suggest that it is also a main-sequence star. The separation of the two stars varies between about 0.05″ and 0.2″ during the eccentric 182-day orbit. [14]

The primary star has a mass fractionally higher than the Sun's, but is significantly larger and hotter resulting in it being 86% more luminous. [3] Its age is estimated to be about five billion years. [2]

The secondary only has about three-quarters the mass of the Sun and is both cooler and smaller. It is only about 29% as luminous. [3] It is calculated to be 2.13 magnitudes fainter than the primary, so it would be of sixth magnitude if visible alone. [15]

Visual companions

Multiple star catalogues list faint widely-separated visible companion stars: a 12th-magnitude star and a 14th-magnitude star about 3′ from χ Draconis, but only about 10″ from each-other. [16] Both have much smaller parallaxes than χ Draconis and are unrelated background objects. [17]

See also

References

  1. 1 2 3 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. S2CID   18759600.
  2. 1 2 3 4 5 6 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. S2CID   11027621.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 Torres, G.; Andersen, J.; Giménez, A. (2010). "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. S2CID   14006009. See p. 56, entry #15.
  4. 1 2 3 Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven. Bibcode:1991bsc..book.....H.
  5. ↑ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
  6. ↑ 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 .
  7. ↑ 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 .
  8. ↑ "chi Dra -- Star in double system". SIMBAD. Centre de Données astronomiques de Strasbourg . Retrieved 2011-10-15.
  9. ↑ Reylé, Céline; Jardine, Kevin; Fouqué, Pascal; Caballero, Jose A.; Smart, Richard L.; Sozzetti, Alessandro (30 April 2021). "The 10 parsec sample in the Gaia era". Astronomy & Astrophysics . 650: A201. arXiv: 2104.14972 . Bibcode:2021A&A...650A.201R. doi:10.1051/0004-6361/202140985. S2CID   233476431. Data available at https://gruze.org/10pc/ Archived 12 March 2023 at the Wayback Machine
  10. ↑ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  11. 1 2 Allen, R. H. (1899), Star Names: Their Lore and Meaning, p. 210
  12. 1 2 "AEEA 天文教育資訊網" [Activities of Exhibition and Education in Astronomy] (in Chinese). Archived from the original on 21 May 2011.
  13. ↑ Ridpath, Ian. "Star Tales - Draco" . Retrieved 10 May 2025.
  14. ↑ Tomkin, Jocelyn; McAlister, Harold A.; Hartkopf, William I.; Fekel, Francis C. (1987). "The Orbit of the Speckle and Double-Lined Spectroscopic Binary Chi Draconis". The Astronomical Journal. 93: 1236. Bibcode:1987AJ.....93.1236T. doi: 10.1086/114404 .
  15. ↑ Hutter, D. J.; Zavala, R. T.; Tycner, C.; Benson, J. A.; Hummel, C. A.; Sanborn, J.; Franz, O. G.; Johnston, K. J. (9 November 2016). "Surveying the Bright Stars by Optical Interferometry. I. A Search for Multiplicity Among Stars of Spectral Types F-K". The Astrophysical Journal Supplement Series. 227 (1): 4. arXiv: 1609.05254 . Bibcode:2016ApJS..227....4H. doi: 10.3847/0067-0049/227/1/4 . S2CID   118803592.
  16. ↑ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi: 10.1086/323920 . ISSN   0004-6256.
  17. ↑ 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.
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