Epsilon Ceti

Epsilon Ceti
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Cetus
Right ascension	02h 39m 33.79741s
Declination	−11° 52′ 19.5516″
Apparent magnitude (V)	+4.84
Characteristics
Spectral type	F2V + F7/G4V
U−B color index	−0.02
B−V color index	+0.45
Astrometry
Proper motion (μ)	RA: +167.071 mas/yr ; Dec.: −251.104 mas/yr
Parallax (π)	41.43±0.68 mas
Distance	79 ± 1 ly ; (24.1 ± 0.4 pc)
Absolute magnitude (MV)	+2.68
Orbit
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 M☉
Radius	1.52 R☉
Surface gravity (log g)	4.21±0.14 cgs
Temperature	6,520 K
Metallicity [Fe/H]	−0.08 dex
Rotational velocity (v sin i)	11.5 km/s
Age	1.8 Gyr
ε Cet B
Mass	1.03±0.08 M☉
Radius	1.27 R☉
Temperature	6,370 K
Metallicity [Fe/H]	−0.08 dex
Rotational velocity (v sin i)	2.0 km/s
Other designations
	ε Cet, 83 Cet, BD−12°501, GJ 9091, GJ 105.4, HD 16620, HIP 12390, HR 781, SAO 148528
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 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

^ ^a ^b ^c Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b ^c ^d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
^ ^a ^b ^c ^d ^e ^f ^g ^h 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, Bibcode:2013MNRAS.428..321D, doi:10.1093/mnras/sts045.
^ 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, S2CID 119257644.
^ ^a ^b ^c ^d ^e ^f ^g ^h Fuhrmann, Klaus (February 2008), "Nearby stars of the Galactic disc and halo - IV", Monthly Notices of the Royal Astronomical Society, 384 (1): 173–224, Bibcode:2008MNRAS.384..173F, doi:10.1111/j.1365-2966.2007.12671.x.
^ ^a ^b ^c 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
^ "eps Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-04.{{cite web}}: CS1 maint: postscript (link)
^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 162. ISBN 0-486-21079-0. Retrieved 2010-12-12. {{cite book}}: ISBN / Date incompatibility (help)
^ 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 Archived 2011-05-22 at the Wayback Machine

[GaiaDR2-1] Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.

[Mermilliod1986-2] Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.

[Docobo2013-3] ^ ^a ^b ^c ^d ^e ^f ^g ^h 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, Bibcode:2013MNRAS.428..321D, doi:10.1093/mnras/sts045.

[Anderson2012-4] 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, S2CID 119257644.

[Fuhrmann2008-5] ^ ^a ^b ^c ^d ^e ^f ^g ^h Fuhrmann, Klaus (February 2008), "Nearby stars of the Galactic disc and halo - IV", Monthly Notices of the Royal Astronomical Society, 384 (1): 173–224, Bibcode:2008MNRAS.384..173F, doi:10.1111/j.1365-2966.2007.12671.x.

[David2015-6] 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, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.

[SIMBAD-7] "eps Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-04.{{cite web}}: CS1 maint: postscript (link)

[8] Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 162. ISBN 0-486-21079-0. Retrieved 2010-12-12. {{cite book}}: ISBN / Date incompatibility (help)

[9] 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

[sb10-10] (in Chinese) 夢之大地 @ 國立成功大學 WebBBS DreamLand @ National Cheng Kung University WebBBS System

[11] (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 12 日 Archived 2011-05-22 at the Wayback Machine

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Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Cetus
Right ascension	02^h 39^m 33.79741^s^[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 mas/yr^[1] Dec.: −251.104 mas/yr^[1]
Parallax (π)	41.43±0.68 mas^[3]
Distance	79 ± 1 ly (24.1 ± 0.4 pc)
Absolute magnitude (M_V)	+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
ε Cet, 83 Cet, BD−12°501, GJ 9091, GJ 105.4, HD 16620, HIP 12390, HR 781, SAO 148528^[7]
Database references
SIMBAD	data

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