Sigma Ceti

Sigma Ceti (σ Ceti) is the Bayer designation for a star in the equatorial constellation of Cetus. With an apparent visual magnitude of 4.78,[2] it can be seen with the naked eye on a dark night. Based upon an annual parallax shift of 37.46 mas,[1] it lies at an estimated distance of 87.1 light years from the Sun. It is a probable astrometric binary star system.[11]

Sigma Ceti
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cetus
Right ascension 02h 32m 05.22884s[1]
Declination −15° 14′ 40.8278″[1]
Apparent magnitude (V) 4.78[2]
Characteristics
Spectral type F5 V[3] or F4 IV[4]
U−B color index −0.03[2]
B−V color index +0.45[2]
Astrometry
Radial velocity (Rv)−27.5±0.9[5] km/s
Proper motion (μ) RA: −80.21[1] mas/yr
Dec.: −146.29[1] mas/yr
Parallax (π)37.46 ± 0.25[1] mas
Distance87.1 ± 0.6 ly
(26.7 ± 0.2 pc)
Absolute magnitude (MV)+2.68[3]
Details
σ Cet A
Mass1.21[6] M☉
Radius1.5[7] R☉
Luminosity7.6[8] L☉
Surface gravity (log g)4.07±0.07[9] cgs
Temperature6,527±59[9] K
Metallicity [Fe/H]−0.12±0.04[9] dex
Rotational velocity (v sin i)20[3] km/s
Age2.135[6] Gyr
Other designations
σ Cet, 76 Cet, BD−15° 449, FK5 1071, HD 15798, HIP 11783, HR 740, SAO 148445.[10]
Database references
SIMBADdata

The primary, component A, appears to be a normal F-type main sequence star with a stellar classification of F5 V.[3] However, Malaroda (1975) assigned it a classification of F4 IV,[4] which would suggest it is a more evolved subgiant star. It is estimated to have 121%[6] of the Sun's mass and around 150% of the radius of the Sun.[7] With an age of about 2.1[6] billion years, it is radiating 7.6[8] times the solar luminosity from its outer atmosphere at an effective temperature of 6,527 K.[9]

Name

This star, along with π Cet, ε Cet and ρ Cet, was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's Breast [12]

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, this star (σ Cet) as Al Sadr al Ḳaiṭos II, ε Cet as Al Sadr al Ḳaiṭos III and π Cet as Al Sadr al Ḳaiṭos IV[13]

References
  1. 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.
  2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, (PDF) origin: SIMBAD, Bibcode:1986EgUBV........0M.
  3. Takeda, Yoichi; et al. (February 2005), "High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards", Publications of the Astronomical Society of Japan, 57 (1): 13–25, Bibcode:2005PASJ...57...13T, doi:10.1093/pasj/57.1.13.
  4. Malaroda, S. (August 1975), "Study of the F-type stars. I. MK spectral types", Astronomical Journal, 80: 637–641, Bibcode:1975AJ.....80..637M, doi:10.1086/111786.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  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.
  7. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (3rd ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451.
  8. 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.
  9. Prugniel, Ph.; et al. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769.
  10. "* sig Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-02-09.
  11. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  12. Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 162. ISBN 978-0-486-21079-7. Retrieved 2010-12-12.
  13. 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
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