Zeta Centauri
| |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 55m 32.38565s[1] |
| Declination | −47° 17′ 18.1482″[1] |
| Apparent magnitude (V) | +2.55[2] |
| Characteristics | |
| Spectral type | B2.5 IV[3] |
| U−B color index | −0.91[2] |
| B−V color index | −0.22[2] |
| Astrometry | |
| Radial velocity (Rv) | +6.5[4] km/s |
| Proper motion (μ) | RA: −57.37[1] mas/yr Dec.: −44.55[1] mas/yr |
| Parallax (π) | 8.54 ± 0.13[1] mas |
| Distance | 382 ± 6 ly (117 ± 2 pc) |
| Orbit[5] | |
| Period (P) | 8.024 days |
| Semi-major axis (a) | 0.0014"[6] |
| Eccentricity (e) | 0.5 |
| Periastron epoch (T) | 2413719.321 JD |
| Argument of periastron (ω) (secondary) | 290° |
| Details | |
| Mass | 7.8 ± 0.1[3] M☉ |
| Radius | 5.80 ± 0.53[7] R☉ |
| Surface gravity (log g) | 3.84 ± 0.08[7] cgs |
| Temperature | 23,561 ± 283[7] K |
| Rotational velocity (v sin i) | 235[8] km/s |
| Age | 39.8 ± 5.7[3] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Zeta Centauri (ζ Centauri, ζ Cen) is a binary star system in the southern constellation of Centaurus. It has the proper name Alnair, from the scientific-Arabic[10] Nayyir Badan Qanṭūris (نير بطن قنطورس), meaning "The Bright (Star) of the Body of the Centaur".[11] With a combined apparent visual magnitude of +2.55,[2] it is one of the brighter members of the constellation. This system is close enough to the Earth that its distance can be measured directly using the parallax technique. This yields a value of roughly 382 light-years (117 parsecs), with a 1.6% margin of error.[1]
In Chinese, 庫樓 (Kù Lóu), meaning Arsenal, refers to an asterism consisting of ζ Centauri, η Centauri, θ Centauri, 2 Centauri, HD 117440, ξ1 Centauri, γ Centauri, τ Centauri, D Centauri and σ Centauri.[12] Consequently, ζ Centauri itself is known as 庫樓一 (Kù Lóu yī, English: the First Star of Arsenal.)[13]
ζ Cen is a double-lined spectroscopic binary system,[14] which indicates that the orbital motion was detected by shifts in the absorption lines of their combined spectra caused by the Doppler effect. The two stars orbit each other over a period of slightly more than eight days with an orbital eccentricity of about 0.5.[5] The estimated angular separation of the pair is 1.4 mas.[6]
At an estimated age of 40 million years,[3] the primary component of this system appears to be in the subgiant stage of its evolution with a stellar classification of B2.5 IV.[3] It is a large star with nearly 8[3] times the mass of the Sun and close to 6[7] times the Sun's radius. This star is rotating rapidly with a projected rotational velocity of 235 km s−1.[8]
References
- 1 2 3 4 5 6 van Leeuwen, F. (November 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 4 Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J
- 1 2 3 4 5 6 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x
- ↑ Wilson, R. E. (1953), General Catalogue of Stellar Radial Velocities, Carnegie Institute of Washington D.C., Bibcode:1953GCRV..C......0W
- 1 2 Maury, A. C. (1922), "The Orbit of the Spectroscopic Binary ζ Centauri", Harvard College Observatory Circular, 233: 1–4, Bibcode:1922HarCi.233....1M
- 1 2 Halbwachs, J. L. (April 1981), "List of Estimated Angular Separations of Spectroscopic Binaries", Astronomy and Astrophysics Supplement, 44: 47, Bibcode:1981A&AS...44...47H
- 1 2 3 4 Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855
- 1 2 Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B
- ↑ "zet Cen -- Spectroscopic binary", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-03-01
- ↑ Kunitzsch, P.; Smart, T. (2006), A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd revised ed.), Cambridge, MA: Sky Pub, p. 4, ISBN 978-1-931559-44-7
- ↑ ibid., p.28.
- ↑ (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.
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日
- ↑ van Rensbergen, W.; De Loore, C.; Jansen, K. (February 2006), "Evolution of interacting binaries with a B type primary at birth", Astronomy and Astrophysics, 446 (3): 1071–1079, Bibcode:2006A&A...446.1071V, doi:10.1051/0004-6361:20053543