Astronomy:Theta Ceti
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Cetus |
| Right ascension | 01h 24m 01.40528s[1] |
| Declination | −08° 10′ 59.7212″[1] |
| Apparent magnitude (V) | 3.60[2] |
| Characteristics | |
| Spectral type | K0 III[3] |
| B−V color index | +1.07[2] |
| Astrometry | |
| Radial velocity (Rv) | +17.2±0.5[4] km/s |
| Proper motion (μ) | RA: −77.94[1] mas/yr Dec.: −206.53[1] mas/yr |
| Parallax (π) | 28.66 ± 0.19[1] mas |
| Distance | 113.8 ± 0.8 ly (34.9 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.89[5] |
| Details[2] | |
| Mass | 1.80[6] M☉ |
| Radius | 10.04 R☉ |
| Luminosity | 53 L☉ |
| Surface gravity (log g) | 2.70 cgs |
| Temperature | 4,660±17[6] K |
| Metallicity [Fe/H] | −0.13±0.15 dex |
| Rotational velocity (v sin i) | 2.60 km/s |
| Age | 2.20[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Theta Ceti, Latinized from θ Ceti, is a solitary,[8] orange-hued star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.60.[2] Based upon an annual parallax shift of 28.66 mas as seen from Earth,[1] it is located about 114 light-years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.10 due to interstellar dust.[2]
With an age of about 2.2 billion years,[6] this is an evolved, K-type giant star with a stellar classification of K0 III.[3] It is a red clump[9] star on the horizontal branch,[2] which means it is generating energy through helium fusion at its core.[9] The star has an estimated 1.8[6] times the mass of the Sun and has expanded to 10 times the Sun's radius.[2] It is radiating 53[2] times the solar luminosity from its photosphere at an effective temperature of 4,660 K.[6]
Name
In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Thanih al Naamat (ثاني النعامات - thānī al-naʽāmāt), which was translated into Latin as Secunda Struthionum, meaning the second ostrich.[10] This star, along with η Cet (Deneb Algenubi), τ Cet (Thalath Al Naamat), ζ Cet (Baten Kaitos) and υ Cet, were Al Naʽāmāt (النعامات), the Hen Ostriches.[11][12]
In Chinese, 天倉 (Tiān Cāng), meaning Square Celestial Granary, refers to an asterism consisting of θ Ceti, ι Ceti, η Ceti, ζ Ceti, τ Ceti and 57 Ceti.[13] Consequently, the Chinese name for θ Ceti itself is 天倉三 (Tiān Cāng sān, English: the Third Star of Square Celestial Granary).[14]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Jones, M. I. et al. (December 2011), "Study of the impact of the post-MS evolution of the host star on the orbits of close-in planets. I. Sample definition and physical properties", Astronomy & Astrophysics 536: 7, doi:10.1051/0004-6361/201117887, A71, Bibcode: 2011A&A...536A..71J.
- ↑ 3.0 3.1 Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey (Ann Arbor, Michigan: Department of Astronomy, University of Michigan) 5, Bibcode: 1999MSS...C05....0H.
- ↑ 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal 150 (3): 88, doi:10.1088/0004-6256/150/3/88, Bibcode: 2015AJ....150...88L.
- ↑ "tet Cet -- Horizontal Branch Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=tet+Cet, retrieved 2017-04-25.
- ↑ 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ 9.0 9.1 Laney, C. D. et al. (January 2012), "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars", Monthly Notices of the Royal Astronomical Society 419 (2): 1637–1641, doi:10.1111/j.1365-2966.2011.19826.x, Bibcode: 2012MNRAS.419.1637L.
- ↑ Knobel, E. B. (June 1895), "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket", Monthly Notices of the Royal Astronomical Society 55: 429, doi:10.1093/mnras/55.8.429, Bibcode: 1895MNRAS..55..429K.
- ↑ Allen, R. H. (1963), 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 2017-04-26.
- ↑ η Cet as Aoul al Naamat or Prima Struthionum (the first ostrich), θ Cet as Thanih al Naamat or Secunda Struthionum (the second ostrich), τ Cet as Thalath al Naamat or Tertia Struthionum (the third ostrich), and ζ Cet as Rabah al Naamat or Quarta Struthionum (the fourth ostrich). υ Cet should be Khamis al Naamat or Quinta Struthionum (the fifth ostrich) consistently, but Al Achsasi Al Mouakket designated the title the fifth ostrich to γ Gam with uncleared consideration.
- ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN:978-986-7332-25-7.
- ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日
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