Astronomy:Xi Cephei

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Short description: Star in the constellation Cepheus
ξ Cephei
Location of ξ Cephei (circled)
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|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[1] mas/yr
Dec.: +89.058[1] mas/yr
Parallax (π)32.12 ± 0.8066[1] mas
Distance102 ± 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
Dec.: +81/933 mas/yr
Parallax (π)32.1835 ± 0.0184[4] mas
Distance101.34 ± 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
Mass1.721+0.134
−0.120[9] M☉
Luminosity6.6[11] L☉
Temperature7,943[11] K
Age200[11] Myr
Ab
Mass0.512[9][lower-alpha 1] M☉
Luminosity1.8[11] L☉
Temperature6,310[11] K
Age525[11] Myr
B
Mass1.14[4] M☉
Radius1.28[4] R☉
Luminosity2.08[4] L☉
Surface gravity (log g)4.26[4] cgs
Temperature6,123[4] K
Age3.98[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
SIMBADξ
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.

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 (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").[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. ↑ 1.0 1.1 1.2 1.3 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ Fabricius, C. et al. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics 384: 180. doi:10.1051/0004-6361:20011822. Bibcode: 2002A&A...384..180F. 
  3. ↑ 3.0 3.1 3.2 3.3 Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series 235 (1): 6. doi:10.3847/1538-4365/aaa1a5. Bibcode: 2018ApJS..235....6T. 
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  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. doi:10.1086/191315. Bibcode: 1989ApJS...69..301G. 
  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. doi:10.1086/319956. Bibcode: 2001AJ....121.2148G. 
  8. ↑ 8.0 8.1 Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode: 1953GCRV..C......0W. 
  9. ↑ 9.0 9.1 9.2 Videla, Miguel et al. (April 2022). "Bayesian Inference in Single-line Spectroscopic Binaries with a Visual Orbit" (in en). The Astronomical Journal 163 (5): 220. doi:10.3847/1538-3881/ac5ab4. ISSN 1538-3881. Bibcode: 2022AJ....163..220V. 
  10. ↑ 10.0 10.1 10.2 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. doi:10.1088/0004-6256/148/3/48. Bibcode: 2014AJ....148...48F. 
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 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. doi:10.1093/mnras/stz3616. Bibcode: 2020MNRAS.492.2709P. 
  12. ↑ "xi. Cep". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=xi.+Cep. 
  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. ↑ 14.0 14.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. 
  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". http://www.icoproject.org/star.html. 
  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)). https://archive.org/details/starnamestheirlo00alle/page/159. Retrieved 2010-12-12. 
  18. ↑ "IAU Working Group on Star Names (WGSN)". International Astronomical Union. https://www.iau.org/science/scientific_bodies/working_groups/280/. 
  19. ↑ "WG Triennial Report (2015-2018) - Star Names". p. 5. https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf. 
  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 , 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. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M. 
  23. ↑ Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.



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