Astronomy:Epsilon Ceti
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 02h 39m 33.79741s[2] |
| Declination | −11° 52′ 19.5516″[2] |
| Apparent magnitude (V) | +4.84[3] |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | F2V + F7/G4V[4] |
| U−B color index | −0.02[3] |
| B−V color index | +0.45[3] |
| Astrometry | |
| Radial velocity (Rv) | 15.49±0.19[5] km/s |
| Proper motion (μ) | RA: +167.071[2] mas/yr Dec.: −251.104[2] mas/yr |
| Parallax (π) | 41.43 ± 0.68[4] mas |
| Distance | 79 ± 1 ly (24.1 ± 0.4 pc) |
| Absolute magnitude (MV) | +2.68[1] |
| Orbit[4] | |
| 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[4] M☉ |
| Radius | 1.52[6] R☉ |
| Surface gravity (log g) | 4.21±0.14[7] cgs |
| Temperature | 6,520[6] K |
| Metallicity [Fe/H] | −0.08[6] dex |
| Rotational velocity (v sin i) | 11.5[6] km/s |
| Age | 1.8[7] Gyr |
| ε Cet B | |
| Mass | 1.03±0.08[4] M☉ |
| Radius | 1.27[6] R☉ |
| Temperature | 6,370[6] K |
| Metallicity [Fe/H] | −0.08[6] dex |
| Rotational velocity (v sin i) | 2.0[6] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Ceti is a binary star system located in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from ε Ceti and abbreviated Epsilon Cet or ε Cet. This system is faintly visible to the naked eye as a point of light with an apparent visual magnitude of +4.84.[3] Based upon an annual parallax shift of 41.43 mas,[4] 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° to the plane of the sky.
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.[4] The system is estimated to be 1.8 billion years old,[7] with the primary having 1.4 times the mass of the Sun and the secondary being about equal to the Sun's mass.[4]
Name
This star, along with π Cet, ρ Cet and σ Cet, was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's Breast.[9]
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.[10]
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.[11] Consequently, the Chinese name for ε Ceti itself is 芻蒿六 (Chú Hāo liù, English: the Sixth Star of Celestial Meadows).[12]
References
- ↑ 1.0 1.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A XHIP record for this object at VizieR.
- ↑ 2.0 2.1 2.2 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. 5171076479048181760 Gaia DR2 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 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.
- ↑ Pourbaix, D. et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics 424 (2): 727–732, doi:10.1051/0004-6361:20041213, Bibcode: 2004A&A...424..727P.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 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.
- ↑ 7.0 7.1 7.2 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.
- ↑ 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.
- ↑ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology, https://ntrs.nasa.gov/citations/19720005197, retrieved 2026-02-13.
- ↑ Script error: The function "in_lang" does not exist. 夢之大地 @ 國立成功大學 WebBBS DreamLand @ National Cheng Kung University WebBBS System
- ↑ Script error: The function "in_lang" does not exist. AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 12 日
 |  |
