Delta Ceti

Delta Ceti, Latinized from δ Ceti, is a single,[7] blue-white hued star in the equatorial constellation of Cetus. It is positioned very near the celestial equator and is located about 0.74 degrees WNW of the spiral galaxy M77. With an apparent visual magnitude of +4.06,[2] it is a faint star but visible to the naked eye. Based upon an annual parallax shift of 5.02 mas as seen from Earth,[1] it is located around 650 light years from the Sun. The star is moving away from the Sun with a radial velocity of +13 km/s.[4]

Delta Ceti
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension  02h 39m 28.95579s[1]
Declination +00° 19′ 42.6345″[1]
Apparent magnitude (V) +4.06[2]
Characteristics
Spectral type B2 IV[3]
U−B color index −0.88[2]
B−V color index −0.21[2]
Variable type β Cep[3]
Astrometry
Radial velocity (Rv)12.7±0.9[4] km/s
Proper motion (μ) RA: 12.85±0.17[1] mas/yr
Dec.: −2.94±0.11[1] mas/yr
Parallax (π)5.02 ± 0.15[1] mas
Distance650 ± 20 ly
(199 ± 6 pc)
Absolute magnitude (MV)−2.41[5]
Details
Mass8.4±0.7[3] M☉
Radius4.6±0.8[3] R☉
Luminosity4,000[3] L☉
Surface gravity (log g)4.05±0.20[3] cgs
Temperature21,900±1,000[3] K
Metallicity [Fe/H]−0.24[5] dex
Rotational velocity (v sin i)7±4[3] km/s
Age7−18[6] Myr
Other designations
δ Cet, 82 Ceti, BD−00° 406, FK5 91, HD 16582, HIP 12387, HR 779, SAO 110665
Database references
SIMBADdata

This is a Beta Cephei variable[3] with a stellar classification of B2 IV.[3] It varies in brightness with a period of 0.16114 days.[6] The star is about 7−18[6] million years and has a low projected rotational velocity of around 7 km/s,[3] suggesting it is either rotating slowly or is being viewed from nearly pole on.[6] It has 8.4[3] times the mass of the Sun and 4.6[3] times the Sun's radius. The star is radiating around 4,000[3] times the Sun's luminosity from its photosphere at an effective temperature of roughly 21,900 K[3]

Name

This star, along with α Cet (Menkar), λ Cet (Menkar), γ Cet (Kaffaljidhma), μ Cet, ξ1 Cet and ξ2 Cet were Al Kaff al Jidhmah, "the Part of a Hand".[8]

According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Kaff al Jidhmah were the title for five stars :γ Cet as Kaffaljidhma, ξ1 Cet as Al Kaff al Jidhmah I, ξ2 Cet as Al Kaff al Jidhmah II, δ Cet as Al Kaff al Jidhmah III and μ Cet as Al Kaff al Jidhmah IV (exclude α Cet and λ Cet.)[9]

In Chinese, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of δ Ceti, α Ceti, κ1 Ceti, λ Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for δ Ceti itself is 天囷九 (Tiān Qūn jiǔ, English: the Ninth Star of Circular Celestial Granary.)[10]

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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.Vizier catalog entry
  2. Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J.
  3. Hubrig, S.; et al. (January 2009), "New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars", Astronomische Nachrichten, 330 (4): 317, arXiv:0902.1314, Bibcode:2009AN....330..317H, doi:10.1002/asna.200811187
  4. 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.
  5. 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.
  6. Neilson, Hilding R.; Ignace, Richard (December 2015), "Period change and stellar evolution of β Cephei stars", Astronomy & Astrophysics, 584: 6, arXiv:1509.05433, Bibcode:2015A&A...584A..58N, doi:10.1051/0004-6361/201526836, A58.
  7. 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.
  8. Star Name - R.H. Allen p.160
  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
  10. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日
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