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ξ Cephei

Location of ξ Cephei (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Cepheus
Right ascension	22 03 47.455
Declination	+64° 37′ 40.71″
Apparent magnitude (V)	4.2 (4.45 + 4.60)
Characteristics
ξ Cephei A
Spectral type	kA2.5hF2mF2(IV)
ξ Cephei B
Spectral type	F8V
Astrometry
Proper motion (μ)	RA: 215.46±1.14 mas/yr Dec.: 91.06±0.97 mas/yr
Parallax (π)	38.10 ± 2.81 mas
Distance	86 ± 6 ly (26 ± 2 pc)
Absolute magnitude (MV)	+1.79
Orbit
Period (P)	810.9 d
Eccentricity (e)	0.46
Periastron epoch (T)	2438529.8 JD
Argument of periastron (ω) (secondary)	106°
Semi-amplitude (K1) (primary)	7.1 km/s
Semi-amplitude (K2) (secondary)	19.9 km/s
Details
ξ Cephei Aa
Mass	1.045±0.031 M☉
ξ Cephei Ab
Mass	0.408±0.066 M☉
Other designations
Kurhah, 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
SIMBAD	ξ
	A
	B

Xi Cephei (ξ Cephei, abbreviated Xi Cep, ξ Cep) is a multiple star system in the constellation of Cepheus. It is approximately 86 light-years from Earth.

It consists of two binary stars, designated Xi Cephei A and B, together with a more distant companion, Xi Cephei C. A's two components are themselves designated Xi Cephei Aa (officially named Kurhah /ˈkɜːrhə/, the traditional name of the system) and Ab.

Nomenclature

ξ Cephei (Latinised to Xi Cephei) is the system's Bayer designation. The designations of the three constituents as ξ Cephei A, B and C, and those of A's components - ξ Cephei Aa and Ab - derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).

Xi Cephei bore the traditional names Kurhah, Alkirdah or Al Kirduh, 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"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Kurhah for the component Xi Cephei Aa on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.

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. Consequently, the Chinese name for Xi Cephei itself is 天鈎六 (Tiān Gōu liù, English: the Sixth Star of Celestial Hook).

Properties

Xi Cephei A is a double-lined spectroscopic binary system with an orbital period of 810.9 days and an eccentricity of 0.46. The primary, component Aa, is a chemically peculiar Am star, a probable subgiant with an apparent magnitude of +4.29. Eight arcseconds away, Xi Cephei B is another spectroscopic binary. Xi Cephei C is a 13th magnitude star nearly two arcminutes away.

References

1. ^ 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. S2CID 18759600.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): 984–993. arXiv:astro-ph/0210694. Bibcode:2003AJ....125..984M. doi:10.1086/345888. S2CID 55896673.
3. ^ 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. Gray, R. O; Garrison, R. F (1989). "The early F-type stars - Refined classification, confrontation with Stromgren photometry, and the effects of rotation". The Astrophysical Journal Supplement Series. 69: 301. Bibcode:1989ApJS...69..301G. doi:10.1086/191315.
5. Gray, R. O; Napier, M. G; Winkler, L. I (2001). "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars". The Astronomical Journal. 121 (4): 2148. Bibcode:2001AJ....121.2148G. doi:10.1086/319956.
6. ^ Farrington, C. D.; et al. (2014). "Separated Fringe Packet Observations with the CHARA Array. II. omega Andromeda, HD 178911, and xi Cephei". The Astronomical Journal. 148 (3): 48. arXiv:1407.0639. Bibcode:2014AJ....148...48F. doi:10.1088/0004-6256/148/3/48. S2CID 12909818.
7. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
8. ^ Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; et al. (2004), "S_B: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088.
9. ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.
10. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 .
11. "Islamic Crescent Project: Star names". Archived from the original on 2008-02-02. Retrieved 2010-12-08.
12. 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.
13. IAU Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
14. "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
15. (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.
16. (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.

v t e Constellation of Cepheus
List of stars in Cepheus Cepheus in Chinese astronomy
Stars	Bayer α (Alderamin) β (Alfirk) γ (Errai) δ ε ζ η θ ι κ λ μ (Garnet Star) ν ξ (Kurhah) ο π ρ ρ Flamsteed 7 9 11 14 16 19 24 2 UMi Variable AR T V W RW VV VW WZ DH DO MY PV S SS ST U V354 V381 V419 HR 597 881 7955 8281 8442 8702 8748 8938 9038 HD 1 197911 204521 Other Gliese 809 WISE 0313+7807 WR 156 IRAS 23077+6707
Exoplanets γ Cephei Ab (Tadmor) TOI-1431 b
Star clusters	NGC 188 6939 7023 7129 7142 7160 7380 7419 7429 7510 Other Palomar 1
Nebulae	NGC NGC 40 NGC 7129 NGC 7139 NGC 7354 NGC 7538 NGC 7822 Other Seahorse Nebula Elephant's Trunk Nebula Ghost Nebula Gyulbudaghian's Nebula IC 1396 Iris Nebula L1157 S 155 SSTGFLS J222557+601148
Galaxies	NGC 2276 2300 6952 Other 3C 61.1 S5 0014+81 NVSS 2146+82 UGC 11861
Category

• Cepheus (constellation)
• Bayer objects
• A-type main-sequence stars
• Stars with proper names
• Flamsteed objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Durchmusterung objects
• Bright Star Catalogue objects
• Spectroscopic binaries
• Am stars
• F-type main-sequence stars
• F-type subgiants