Xi2 Ceti
Star in the constellation Cetus
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Xi2 Ceti is a star located in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from ξ2 Ceti, and abbreviated Xi2 Cet or ξ2 Cet. This star is visible to the naked eye with an apparent visual magnitude of +4.3.[3] This star is located at a distance of approximately 197 light years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 12 km/s.[6] It made its closest approach some 2.7 million years ago at a distance of around 128 light-years.[1]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 02h 28m 09.55706s[2] |
| Declination | +08° 27′ 36.2168″[2] |
| Apparent magnitude (V) | +4.279[3] |
| Characteristics | |
| Spectral type | B9.5III[4] or A0III-[5] |
| U−B color index | −0.137[1] |
| B−V color index | −0.053±0.003[1] |
| Astrometry | |
| Radial velocity (Rv) | 11.90±1.3[6] km/s |
| Proper motion (μ) | RA: 23.707±0.844 mas/yr[2] Dec.: −4.787±0.778 mas/yr[2] |
| Parallax (π) | 16.5681±0.4608 mas[2] |
| Distance | 197 ± 5 ly (60 ± 2 pc) |
| Absolute magnitude (MV) | +0.45[1] |
| Details | |
| Mass | 2.45[7] M☉ |
| Radius | 2.60±0.17[8] R☉ |
| Luminosity | 80.13[1] L☉ |
| Surface gravity (log g) | 4.00±0.25[8] cgs |
| Temperature | 10,630±400[9] K |
| Metallicity [Fe/H] | −0.43±0.04[1] dex |
| Rotational velocity (v sin i) | 55[7] km/s |
| Age | 127[7] Myr |
| Other designations | |
| ξ2 Cet, 73 Ceti, BD+07°388, HD 15318, HIP 11484, HR 718, SAO 110543[10] | |
| Database references | |
| SIMBAD | data |
Xi2 Ceti is a spectrophotometric standard star.[3] It displays a stellar classification of B9.5III,[4] which suggests it has exhausted its core hydrogen, evolved away from the main sequence, and expanded to become a giant star, although still only 127 million years old.[7] It has 2.45[7] times the mass and 2.6[8] times the radius of the Sun. The star is radiating 80[1] times the Sun's luminosity from its photosphere at an effective temperature of 10,630.[9] It has a high rate of spin, showing a projected rotational velocity of 55 km/s.[7]
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 Xi2 Ceti itself is "the Sixth Star of Circular Celestial Granary", Tiān Qūn Liù.[11]