Nu Ceti
Binary star system in the constellation Cetus
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Nu Ceti is a binary star[5] system in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from ν Ceti, and abbreviated ν Ceti or ν Cet. This system is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.86.[2] It is located approximately 340 light years distant from the Sun, based on parallax measurements, 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.[11]
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| 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 mas/yr[1] Dec.: −22.32±0.22 mas/yr[1] |
| Parallax (π) | 9.59±0.23 mas[1] |
| Distance | 340 ± 8 ly (104 ± 3 pc) |
| Absolute magnitude (MV) | −0.415[6] |
| Orbit[5] | |
| Primary | ν 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 | |
| Mass | 2.65[7] M☉ |
| Radius | 15.87+1.06 −2.19[8] R☉ |
| Luminosity | 161.4±7.9[8] L☉ |
| Surface gravity (log g) | 2.56[7] cgs |
| Temperature | 5,164+417 −164[8] K |
| Age | 537[7] Myr |
| B | |
| Mass | 1.124[9] M☉ |
| Radius | 1.075[9] R☉ |
| Luminosity | 1.421[9] L☉ |
| Surface gravity (log g) | 4.36[9] cgs |
| Temperature | 6,077[9] K |
| Age | 1.3[9] Gyr |
| Other designations | |
| Struve 281, 78 Ceti, BD+04°418, HD 16161, HIP 12093, HR 754, SAO 110635, WDS J02359+0536[10] | |
| Database references | |
| SIMBAD | data |
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.[12]
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]