Xi Cephei

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ξ Cephei
Cepheus constellation map.svg
Red circle.svg
Location of ξ Cephei (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Cepheus
A
Right ascension 22h 03m 47.440s [1]
Declination +64° 37′ 40.70″ [1]
Apparent magnitude  (V)4.45 [2] (4.61 + 6.50)‍ [3]
B
Right ascension 22h 03m 46.217s [4]
Declination +64° 37′ 41.47″ [4]
Apparent magnitude  (V)6.34 [5]
Characteristics
A
Spectral type kA2.5hF2mF2(IV) [6] (A3Vm + F2III)‍ [3]
B
Evolutionary stage main sequence [4]
Spectral type F8V [7]
Astrometry
A
Radial velocity (Rv)−7.2±2 [8] km/s
Proper motion (μ)RA: +212.563 mas/yr [1]
Dec.: +89.058 mas/yr [1]
Parallax (π)32.12±0.8066  mas [1]
Distance 102 ± 3  ly
(31.1 ± 0.8  pc)
B
Radial velocity (Rv)−6.2±2 [8] km/s
Proper motion (μ)RA: +202.094 mas/yr [4]
Dec.: +81/933 mas/yr [4]
Parallax (π)32.1835±0.0184  mas [4]
Distance 101.34 ± 0.06  ly
(31.07 ± 0.02  pc)
Orbit [9]
Period (P)2.245+0.001
−0.000 years
Semi-major axis (a)0.072+0.000
−0.001″
Eccentricity (e)0.460+0.009
−0.008
Inclination (i)67.447+0.508
−0.443°
Longitude of the node (Ω)272.995+0.702
−0.301°
Periastron epoch (T)1968.751+7
−5
Argument of periastron (ω)
(secondary)		90.354+0.315
−0.418°
Semi-amplitude (K1)
(primary)		7.81 [10]  km/s
Semi-amplitude (K2)
(secondary)		19.98 [10]  km/s
Details
Aa
Mass 1.721+0.134
−0.120 [9]   M☉
Luminosity 6.6 [11]   L☉
Temperature 7,943 [11]   K
Age 200 [11]   Myr
Ab
Mass 0.512 [9] [a]   M☉
Luminosity1.8 [11]   L☉
Temperature 6,310 [11]   K
Age 525 [11]   Myr
B
Mass 1.14 [4]   M☉
Radius 1.28 [4]   R☉
Luminosity 2.08 [4]   L☉
Surface gravity (log g)4.26 [4]   cgs
Temperature 6,123 [4]   K
Age 3.98 [4]   Gyr
Other designations
Kurhah, 17 Cephei, BD+63°1802, HIP 108917, HR 8417, SAO 19827, CCDM J22038+2407, WDS J22038+6438 [12]
A: HD 209790
B: HD 209791
Database references
SIMBAD ξ
A
B

Xi Cephei is a multiple star system in the northern constellation of Cepheus. Its name is a Bayer designation. This system is visible to the naked eye as a point of light with a combined apparent visual magnitude of 4.29. [13] Based on parallax measurements, it is located at a distance of approximately 102 light-years from Earth.

Contents

This system consists of a binary pair, designated Xi Cephei A, together with a more distant companion, Xi Cephei B. A's two components are themselves designated Xi Cephei Aa (officially named Kurhah /ˈkɜːrhə/ , the traditional name of the system) [14] and Ab.

Nomenclature

ξ Cephei, Latinized to Xi Cephei, is the system's Bayer designation. It is abbreviated Xi Cep or ξ Cep. 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). [15]

Xi Cephei bore the traditional names Kurhah, Alkirdah or Al Kirduh, [16] the name coming from Qazvini who gave Al Ḳurḥaḥ (القرحةal-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"). [17] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [18] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. [19] 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. [14]

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. [20] Consequently, the Chinese name for Xi Cephei itself is 天鈎六 (Tiān Gōu liù, English: the Sixth Star of Celestial Hook). [21]

Properties

Xi Cephei A is a double-lined spectroscopic binary system with an orbital period of 820 days and an eccentricity of 0.5. [10] The primary, component Aa, is a chemically peculiar Am star with an apparent magnitude of +4.61. The spectroscopic secondary, component Ab, is an F-type star. [3]

Eight arcseconds away from Xi Cephei A, Xi Cephei B is a 6th-magnitude main sequence star. [3]

Xi Cephei C is a 13th magnitude star nearly two arcminutes away. [22] It has a small parallax and is an unrelated background star only accidentally in line with Xi Cephei. [23]

Notes

  1. ↑ from primary mass and mass ratio

References

  1. 1 2 3 4 5 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. ↑ Fabricius, C.; et al. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
  3. 1 2 3 4 Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv: 1712.04750 . Bibcode:2018ApJS..235....6T. doi: 10.3847/1538-4365/aaa1a5 .
  4. 1 2 3 4 5 6 7 8 9 10 11 12 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 .
  5. ↑ Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355. Bibcode:2000A&A...355L..27H.
  6. ↑ 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.
  7. ↑ Gray, R. O; et al. (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.
  8. 1 2 Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
  9. 1 2 3 Videla, Miguel; et al. (April 2022). "Bayesian Inference in Single-line Spectroscopic Binaries with a Visual Orbit". The Astronomical Journal. 163 (5): 220. arXiv: 2203.07438 . Bibcode:2022AJ....163..220V. doi: 10.3847/1538-3881/ac5ab4 . ISSN   1538-3881.
  10. 1 2 3 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.
  11. 1 2 3 4 5 6 Piccotti, Luca; et al. (2020). "A study of the physical properties of SB2s with both the visual and spectroscopic orbits". Monthly Notices of the Royal Astronomical Society. 492 (2): 2709. Bibcode:2020MNRAS.492.2709P. doi: 10.1093/mnras/stz3616 .
  12. ↑ "xi. Cep". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2026-02-01.
  13. ↑ Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". Journal of the American Association of Variable Star Observers (Jaavso). 42 (2): 443. Bibcode:2014JAVSO..42..443M.
  14. 1 2 "Naming Stars". IAU.org. Archived from the original on 11 April 2020. Retrieved 16 December 2017.
  15. ↑ Hessman, F. V.; et al. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv: 1012.0707 [astro-ph.SR].
  16. ↑ "Islamic Crescent Project: Star names". Archived from the original on 2008-02-02. Retrieved 2010-12-08.
  17. ↑ 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.{{cite book}}: CS1 maint: ignored ISBN errors (link)
  18. ↑ "IAU Working Group on Star Names (WGSN)". International Astronomical Union. Archived from the original on 10 June 2016. Retrieved 22 May 2016.{{cite web}}: CS1 maint: postscript (link)
  19. ↑ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Archived from the original (PDF) on 2022-10-09. Retrieved 2018-07-14.
  20. ↑ (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.
  21. ↑ (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.
  22. ↑ Mason, Brian D.; et al. (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 .
  23. ↑ 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 .
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