Location of δ Ceti (circled) | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 02 39 28.95579 |
| Declination | +00° 19′ 42.6345″ |
| Apparent magnitude (V) | +4.06 |
| Characteristics | |
| Spectral type | B2 IV |
| U−B color index | −0.88 |
| B−V color index | −0.21 |
| Variable type | β Cep |
| Astrometry | |
| Radial velocity (Rv) | 12.7±0.9 km/s |
| Proper motion (μ) | RA: 12.85±0.17 mas/yr Dec.: −2.94±0.11 mas/yr |
| Parallax (π) | 5.02 ± 0.15 mas |
| Distance | 650 ± 20 ly (199 ± 6 pc) |
| Absolute magnitude (MV) | −2.41 |
| Details | |
| Mass | 8.4±0.7 M☉ |
| Radius | 4.6±0.8 R☉ |
| Luminosity | 4,000 L☉ |
| Surface gravity (log g) | 4.05±0.20 cgs |
| Temperature | 21,900±1,000 K |
| Metallicity | −0.24 dex |
| Rotational velocity (v sin i) | 7±4 km/s |
| Age | 7−18 Myr |
| Other designations | |
| δ Cet, del Cet, 82 Ceti, BD−00° 406, FK5 91, HD 16582, HIP 12387, HR 779, SAO 110665 | |
| Database references | |
| SIMBAD | data |
Delta Ceti, Latinized from δ Ceti, is a single, blue-white hued star in the equatorial constellation of Cetus. The star's apparent visual magnitude of +4.06 means it is near to the cusp of the faintest third of the stars that are visible the ideally-placed naked eye. It is 0.3238° north of the celestial equator compared to the celestial north pole's 90°. The star is positioned about 0.74° WNW of the spiral galaxy M77, but which at apparent magnitude 9.6 needs magnification to be made out and has an apparent size of only 0.1° by 0.12°.
Based upon an annual parallax shift of 5.02 mas as seen from Earth, it is around 650 light years from the Sun. Motion relative to our system's trajectory includes a highly parting vector: with a net radial velocity of about +13 km/s. It moves minutely across the celestial sphere – yet just over four times more in right ascension than in declination.
This is a Beta Cephei variable with a stellar classification of B2 IV. It varies in brightness with a period of 0.16114 days. Unlike most stars of its type, it does not display multiple periods of luminosity variation or multiple variations of its spectral line profiles. The star is about 7−18 million years and has a low projected rotational velocity of around 7 km/s, suggesting it is either rotating slowly or is being viewed from nearly pole on. It has 8.4 times the mass of the Sun and 4.6 times the Sun's radius. The star is radiating around 4,000 times the Sun's luminosity from its photosphere at an effective temperature of roughly 21,900 K
Name
This star, along with α Cet (Menkar), λ Cet (Menkar), γ Cet (Kaffaljidhma), μ Cet, ξ Cet and ξ Cet were Al Kaff al Jidhmah, "the Part of a Hand".
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, ξ Cet as Al Kaff al Jidhmah I, ξ 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.)
In Chinese, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of δ Ceti, α Ceti, κ Ceti, λ Ceti, μ Ceti, ξ Ceti, ξ 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.)
References
- ^ 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. S2CID 18759600.Vizier catalog entry
- ^ 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): 99. Bibcode:1966CoLPL...4...99J.
- ^ 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, S2CID 17497112
- ^ 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, S2CID 59451347, A61.
- ^ 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.
- ^ 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, S2CID 55220550, A58.
- 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. S2CID 14878976.
- "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
- Cugier, H.; Nowak, D. (October 1997), "Multiwavelength studies of β Cephei stars: δ Ceti", Astronomy and Astrophysics, 326: 620–628, Bibcode:1997A&A...326..620C.
- Star Name - R.H. Allen p.160
- 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) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日 Archived 2012-02-04 at the Wayback Machine
External links
- "del Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-05.
