Theta Cephei
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Cepheus |
Right ascension | 22h 26m 42.40624s[1] |
Declination | +78° 47′ 09.0725″[1] |
Apparent magnitude (V) | 4.22[2] |
Characteristics | |
Spectral type | A7 III[3] |
U−B color index | +0.16[2] |
B−V color index | +0.20[2] |
Astrometry | |
Proper motion (μ) | RA: −13.33[1] mas/yr Dec.: −36.95[1] mas/yr |
Parallax (π) | 15.83 ± 0.23[1] mas |
Distance | 206 ± 3 ly (63.2 ± 0.9 pc) |
Absolute magnitude (MV) | +1.12[4] |
Orbit[5] | |
Period (P) | 840.6 d |
Eccentricity (e) | 0.03 |
Periastron epoch (T) | 2416214.5 JD |
Argument of periastron (ω) (secondary) | 83.7° |
Semi-amplitude (K1) (primary) | 13.9 km/s |
Details | |
θ Cep A | |
Luminosity | 28[6] L☉ |
Surface gravity (log g) | 3.74[3] cgs |
Temperature | 7,816[3] K |
Metallicity [Fe/H] | ±0.04 +0.27[4] dex |
Rotational velocity (v sin i) | 52.0[3] km/s |
Other designations | |
Database references | |
SIMBAD | data |
Theta Cephei, Latinized from θ Cephei, is a stellar class A7, fourth-magnitude star in the constellation Cepheus. It is a white-hued, single-lined spectroscopic binary system, located about 206 light-years from Earth. The pair have an orbital period of 840.6 days with a low eccentricity of 0.03.[5] Shared with η Cep, this star system has the title Al Kidr, meaning unknown[8]
In Chinese, 天鈎 (Tiān Gōu), meaning Celestial Hook, refers to an asterism consisting of 4 Cephei, HD 194298, η Cephei, α Cephei, ξ Cephei, 26 Cephei, ι Cephei and ο Cephei.[9] Consequently, θ Cephei itself is known as 天鈎三 (Tiān Gōu sān, English: the Third Star of Celestial Hook.).[10]
References
- 1 2 3 4 5 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.
- 1 2 3 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
- 1 2 3 4 Takeda, Yoichi; et al. (April 2012), "Lithium, Sodium, and Potassium Abundances in Sharp-Lined A-Type Stars", Publications of the Astronomical Society of Japan, 64 (2): 15, arXiv:1111.1603, Bibcode:2012PASJ...64...38T, doi:10.1093/pasj/64.2.38, 38
- 1 2 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.
- 1 2 Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy & Astrophysics, 424 (2): 727, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
- ↑ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
- ↑ "tet Cep". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-05-06.
- ↑ Allen, Richard Hinckley (1963-06-01). Star Names: Their Lore and Meaning. Dover Publications. p. 155. ISBN 978-0486210797.
- ↑ (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) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 6 日
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