Astronomy:Epsilon Ceti
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cetus |
| Right ascension | 02h 39m 33.79741s[1] |
| Declination | −11° 52′ 19.5516″[1] |
| Apparent magnitude (V) | +4.84[2] |
| Characteristics | |
| Spectral type | F2V + F7/G4V[3] |
| U−B color index | −0.02[2] |
| B−V color index | +0.45[2] |
| Astrometry | |
| Proper motion (μ) | RA: +167.071[1] mas/yr Dec.: −251.104[1] mas/yr |
| Parallax (π) | 41.43 ± 0.68[3] mas |
| Distance | 79 ± 1 ly (24.1 ± 0.4 pc) |
| Absolute magnitude (MV) | +2.68[4] |
| Orbit[3] | |
| Period (P) | 2.6512±0.0005 yr |
| Semi-major axis (a) | 0.1063±0.0005″ |
| Eccentricity (e) | 0.230±0.001 |
| Inclination (i) | 24.2±0.2° |
| Longitude of the node (Ω) | 90.2±0.2° |
| Periastron epoch (T) | 2,012.3109±0.0005 |
| Argument of periastron (ω) (secondary) | 40.8±0.2° |
| Details | |
| ε Cet A | |
| Mass | 1.37±0.09[3] M☉ |
| Radius | 1.52[5] R☉ |
| Surface gravity (log g) | 4.21±0.14[6] cgs |
| Temperature | 6,520[5] K |
| Metallicity [Fe/H] | −0.08[5] dex |
| Rotational velocity (v sin i) | 11.5[5] km/s |
| Age | 1.8[6] Gyr |
| ε Cet B | |
| Mass | 1.03±0.08[3] M☉ |
| Radius | 1.27[5] R☉ |
| Temperature | 6,370[5] K |
| Metallicity [Fe/H] | −0.08[5] dex |
| Rotational velocity (v sin i) | 2.0[5] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Ceti, Latinized from ε Ceti, is a binary star system located in the equatorial constellation of Cetus. It is faintly visible to the naked eye with an apparent visual magnitude of +4.84.[2] Based upon an annual parallax shift of 41.43 mas,[3] it is located around 79 light-years away from the Sun.
This is a line-width spectroscopic binary star system. It has an orbital period of 2.65 years and an eccentricity of 0.23. The semimajor axis is 0.11 astronomical unit|AU, or 11% of the distance between the Sun and the Earth, and the orbital plane is inclined at an angle of 24.2°.The primary member, component A, is an F-type main-sequence star with a stellar classification of F2 V. The spectrum of the secondary, component B, can not be readily separated from that of the primary, so its type can only be estimated as a main-sequence star lying in the range between F7 V and G4 V.[3] The system is estimated to be 1.8 billion years old,[6] with the primary having 1.4 times the mass of the Sun and the secondary being about equal to the Sun's mass.[3]
Name
This star, along with π Cet, ρ Cet and σ Cet, was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's Breast.[8]
According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Sadr al Ḳaiṭos were the title for four stars: ρ Cet as Al Sadr al Ḳaiṭos I, σ Cet as Al Sadr al Ḳaiṭos II, this star (ε Cet) as Al Sadr al Ḳaiṭos III and π Cet as Al Sadr al Ḳaiṭos IV.[9]
In Chinese, 芻蒿 (Chú Hāo), meaning Hay, refers to an asterism consisting of ε Ceti, ρ Ceti, 77 Ceti, 67 Ceti, 71 Ceti and HD 14691.[10] Consequently, the Chinese name for ε Ceti itself is 芻蒿六 (Chú Hāo liù, English: the Sixth Star of Celestial Meadows).[11]
References
- ↑ 1.0 1.1 1.2 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 2.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Docobo, J. A.; Andrade, M. (2013), "Dynamical and physical properties of 22 binaries discovered by W. S. Finsen", Monthly Notices of the Royal Astronomical Society 428 (1): 321–339, doi:10.1093/mnras/sts045, Bibcode: 2013MNRAS.428..321D.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Fuhrmann, Klaus (February 2008), "Nearby stars of the Galactic disc and halo - IV", Monthly Notices of the Royal Astronomical Society 384 (1): 173–224, doi:10.1111/j.1365-2966.2007.12671.x, Bibcode: 2008MNRAS.384..173F.
- ↑ 6.0 6.1 6.2 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D.
- ↑ "eps Cet". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=eps+Cet.
- ↑ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc.. p. 162. ISBN 0-486-21079-0. https://archive.org/details/starnamestheirlo00alle/page/162. Retrieved 2010-12-12.
- ↑ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
- ↑ (in Chinese) 夢之大地 @ 國立成功大學 WebBBS DreamLand @ National Cheng Kung University WebBBS System
- ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 12 日
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