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Xi Cephei
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| 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[1] mas/yr Dec.: +89.058[1] mas/yr |
| 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[4] mas/yr Dec.: +81/933[4] mas/yr |
| 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☉ |
| Luminosity | 1.8[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, 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 102 light-years from Earth and has an apparent magnitude for all the components combined of 4.29.[12]
It consists of a binary star, 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)[13] and Ab.
Nomenclature
[edit]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).[14]
Xi Cephei bore the traditional names Kurhah, Alkirdah or Al Kirduh,[15] 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").[16] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[17] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[18] 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.[13]
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.[19] Consequently, the Chinese name for Xi Cephei itself is 天鈎六 (Tiān Gōu liù, English: the Sixth Star of Celestial Hook).[20]
Properties
[edit]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.[21] It has a small parallax and is an unrelated background star only accidentally in line with Xi Cephei.[22]
Notes
[edit]- ^ from primary mass and mass ratio
References
[edit]- ^ a b c d e 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.
- ^ Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
- ^ a b c d 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.
- ^ a b c d e f g h i j k l 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.
- ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355. Bibcode:2000A&A...355L..27H.
- ^ 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.
- ^ 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.
- ^ a b Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Carnegie Institute Washington D.C. Publication. Bibcode:1953GCRV..C......0W.
- ^ a b c Videla, Miguel; Mendez, Rene A.; Clavería, Rubén M.; Silva, Jorge F.; Orchard, Marcos E. (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.
- ^ a b c 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.
- ^ a b c d e f Piccotti, Luca; Docobo, José Ángel; Carini, Roberta; Tamazian, Vakhtang S.; Brocato, Enzo; Andrade, Manuel; Campo, Pedro P. (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.
- ^ 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.
- ^ a b "Naming Stars". IAU.org. Archived from the original on 11 April 2020. Retrieved 16 December 2017.
- ^ 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 [astro-ph.SR].
- ^ "Islamic Crescent Project: Star names". Archived from the original on 2008-02-02. Retrieved 2010-12-08.
- ^ 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}}: ISBN / Date incompatibility (help) - ^ IAU Working Group on Star Names (WGSN), International Astronomical Union, archived from the original on 10 June 2016, retrieved 22 May 2016.
- ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Archived from the original (PDF) on 2022-10-09. Retrieved 2018-07-14.
- ^ (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.
- ^ (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.
- ^ 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.
- ^ 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.
