Xi Cephei

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ξ Cephei
Observation data
Epoch J2000      Equinox J2000
Constellation Cepheus
Right ascension 22h 03m 47.455s[1]
Declination +64° 37′ 40.71″[1]
Apparent magnitude (V) 4.2[2] (4.45 + 4.60[3])
Spectral type Am + F7/8V[4]
Proper motion (μ) RA: 215.46±1.14[1] mas/yr
Dec.: 91.06±0.97[1] mas/yr
Parallax (π) 38.10 ± 2.81[5] mas
Distance 86 ± 6 ly
(26 ± 2 pc)
Absolute magnitude (MV) +1.79[6]
Period (P) 810.9 d
Eccentricity (e) 0.46
Periastron epoch (T) 2438529.8 JD
Argument of periastron (ω)
Semi-amplitude (K1)
7.1 km/s
Semi-amplitude (K2)
19.9 km/s
ω And A
Mass 1.045±0.031[5] M
Luminosity 16[6] L
ω And B
Mass 0.408±0.066[5] M
Other designations
17 Cephei, BD+63°1802, CCDM J22038+2407, HIP 108917, HR 8417, SAO 19827, WDS J22038+6438
A: HD 209790
B: HD 209791
Database references

Xi Cephei (ξ Cephei, abbreviated Xi Cep, ξ Cep), also named Kurhah,[8] is a binary star in the constellation of Cepheus. It is approximately 86 light years from Earth.[5]


ξ Cephei (Latinised to Xi Cephei) is the system's Bayer designation.

It bore the traditional names Kurhah, Alkirdah or Al Kirduh,[9] the name coming from Qazvini who gave Al Ḳurḥaḥ (القرحة al-qurhah), an Arabic word Ideler translated as a white spot, or blaze, in the face of a horse. Allen indicates that Ideler felt this was not a proper name for a star, and suggested the name Al Ḳirdah (ألقردة al qírada "the Ape").[10] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalogue and standardize proper names for stars. The WGSN approved the name Kurhah for this star on 12 September 2016 and it is now so entered in the IAU Catalog of Star Names.[8]

In Chinese, 天鈎 (Tiān Gōu), meaning Celestial Hook, refers to an asterism consisting of Xi Cephei, 4 Cephei, HD 194298, Eta Cephei, Theta Cephei, Alpha Cephei, 26 Cephei, Iota Cephei and Omicron Cephei.[12] Consequently, Xi Cephei itself is known as 天鈎六 (Tiān Gōu liù, English: the Sixth Star of Celestial Hook.).[13]


This is a double-lined spectroscopic binary system with an orbital period of 810.9 days and an eccentricity of 0.46.[7] The primary, component Aa, is a chemically peculiar Am star belonging to spectral class A3/6Vm[citation needed] and has apparent magnitude +4.29. Eight arc seconds away, ξ Cep B is another spectroscopic binary. There is a 13th magnitude star nearly two arc minutes away that has been listed as component C of the system.[3]


  1. ^ a b c d van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. ^ Monet, David G.; Levine, Stephen E.; Canzian, Blaise; Ables, Harold D.; Bird, Alan R.; Dahn, Conard C.; Guetter, Harry H.; Harris, Hugh C.; Henden, Arne A.; Leggett, Sandy K.; Levison, Harold F.; Luginbuhl, Christian B.; Martini, Joan; Monet, Alice K. B.; Munn, Jeffrey A.; Pier, Jeffrey R.; Rhodes, Albert R.; Riepe, Betty; Sell, Stephen; Stone, Ronald C.; Vrba, Frederick J.; Walker, Richard L.; Westerhout, Gart; Brucato, Robert J.; Reid, I. Neill; Schoening, William; Hartley, M.; Read, M. A.; Tritton, S. B. (2003). "The USNO-B Catalog". The Astronomical Journal. 125 (2): 984. Bibcode:2003AJ....125..984M. arXiv:astro-ph/0210694Freely accessible. doi:10.1086/345888. 
  3. ^ a b Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. 
  4. ^ Ginestet, N.; Carquillat, J. M.; Jaschek, C.; Jaschek, M. (1997). "Spectral classifications in the near infrared of stars with composite spectra. II. Study of a sample of 180 stars". A & A Supplement series. 123: 135. Bibcode:1997A&AS..123..135G. doi:10.1051/aas:1997345. 
  5. ^ a b c d Farrington, C. D.; et al. (2014). "Separated Fringe Packet Observations with the CHARA Array. II. omega Andromeda, HD 178911, and xi Cephei" (PDF). The Astronomical Journal. 148 (3): 48. Bibcode:2014AJ....148...48F. arXiv:1407.0639Freely accessible. doi:10.1088/0004-6256/148/3/48. Archived from the original (PDF) on October 16, 2014. 
  6. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, Bibcode:2012AstL...38..331A, arXiv:1108.4971Freely accessible, doi:10.1134/S1063773712050015. 
  7. ^ a b Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, Bibcode:2004A&A...424..727P, arXiv:astro-ph/0406573Freely accessible, doi:10.1051/0004-6361:20041213. 
  8. ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016. 
  9. ^ Islamic Crescent Project: Star names
  10. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 159. ISBN 0-486-21079-0. Retrieved 2010-12-12. 
  11. ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016. 
  12. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  13. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 29, 2011, at the Wayback Machine., Hong Kong Space Museum. Accessed on line November 23, 2010.