Nu Ceti

ν Ceti, Latinized as Nu Ceti, is a binary star[5] system in the equatorial constellation of Cetus. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.86.[2] The system is located approximately 340 light years distant from the Sun, based on parallax, and is drifting further away with a radial velocity of 4.8 km/s.[5] Nu Ceti is believed to be part of the Ursa Major stream of co-moving stars.[10]

Nu Ceti
Location of ν Ceti (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cetus
Right ascension 02h 35m 52.473s[1]
Declination +05° 35′ 35.69″[1]
Apparent magnitude (V) 4.86[2] + 9.08[3] (visual companion)
Characteristics
Spectral type G8III + F7V (visual companion)[4]
U−B color index 0.52[2]
B−V color index 0.88[2]
Astrometry
Radial velocity (Rv)4.81±0.02[5] km/s
Proper motion (μ) RA: −26.51±0.25[1] mas/yr
Dec.: −22.32±0.22[1] mas/yr
Parallax (π)9.59 ± 0.23[1] mas
Distance340 ± 8 ly
(104 ± 3 pc)
Absolute magnitude (MV)−0.415[6]
Orbit[5]
Primaryν Ceti A
Period (P)714.48±0.15 days
Eccentricity (e)0.274±0.005
Periastron epoch (T)53364.9±1.9
Argument of periastron (ω)
(secondary)		119.5±1.1°
Semi-amplitude (K1)
(primary)		5.09±0.03 km/s
Details
Aa
Mass2.65[7] M☉
Radius15.87+1.06
−2.19[8] R☉
Luminosity161.4±7.9[8] L☉
Surface gravity (log g)2.56[7] cgs
Temperature5,164+417
−164[8] K
Other designations
Struve 281, 78 Ceti, CD−80°365, HD 88351, HIP 12093, HR 754, SAO 258561[9]
Database references
SIMBADdata

In Chinese, 天囷 (Tiān Qūn), meaning Circular Celestial Granary, refers to an asterism consisting of α Ceti, κ1 Ceti, λ Ceti, μ Ceti, ξ1 Ceti, ξ2 Ceti, ν Ceti, γ Ceti, δ Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for ν Ceti itself is "the Seventh Star of Circular Celestial Granary", Tiān Qūn Qī.[11]

The primary, designated component A, forms a single-lined spectroscopic binary with an orbital period of 1.96 years and an eccentricity of 0.27.[5] The visible component is a G-type giant star, currently on the horizontal branch,[7] with a stellar classification of G8III.[4] In addition to the spectroscopic companion there is a visual companion star which shares a common proper motion with Nu Ceti A, designated component B; an F-type main-sequence star with a class of F7V[4] and a 9.08 apparent visual magnitude located 8.0 arcsec away. It was discovered by Struve.[5][3]

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. S2CID 18759600. Vizier catalog entry
  2. Cousins, A. W. J. (1963). "Photometric Data for Stars in the Equatorial Zone (Third List)". Monthly Notes of the Astronomical Society of Southern Africa. 22: 12–17. Bibcode:1963MNSSA..22...12C.
  3. Lutz, T. E.; Lutz, J. H. (1977). "Spectral classification and UBV photometry of bright visual double stars". The Astronomical Journal. 82: 431–434. Bibcode:1977AJ.....82..431L. doi:10.1086/112066.
  4. Stephenson, C. B.; Sanwal, N. B. (1969). "The masses of stars above the main sequence". The Astronomical Journal. 74: 689–704. Bibcode:1969AJ.....74..689S. doi:10.1086/110845.
  5. Griffin, R. F. (2015). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 240: BD+59 224, HD 9592, HD 10171, HD 11738, and nu Ceti". The Observatory. 135: 15–41. Bibcode:2015Obs...135...15G.
  6. "Nu Ceti". Archived from the original on 2013-02-26.
  7. Stock, Stephan; et al. (August 2018), "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search", Astronomy & Astrophysics, 616: 15, arXiv:1805.04094, Bibcode:2018A&A...616A..33S, doi:10.1051/0004-6361/201833111, S2CID 119361866, A33.
  8. 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.
  9. "nu. Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-09-27.
  10. Levato, H.; Abt, H. A. (August 1978), "Spectral types in the Ursa Major stream", Publications of the Astronomical Society of the Pacific, 90: 429−433, Bibcode:1978PASP...90..429L, doi:10.1086/130352.
  11. (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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