Theta Ceti
Orange-hued giant star in the constellation Cetus
From Wikipedia, the free encyclopedia
Theta Ceti is a solitary,[10] orange-hued star in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from θ Ceti, and abbreviated Theta Cet or θ Cet. This star is visible to the naked eye with an apparent visual magnitude of 3.60.[3] Based upon an annual parallax shift of 20.04 mas as seen from Earth,[2] it is located about 112 light-years (34 pc) from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.28 due to interstellar dust.[8] The star is drifting further away with a line of sight velocity component of +17 km/s.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 01h 24m 01.40328s[2] |
| Declination | −08° 10′ 59.7392″[2] |
| Apparent magnitude (V) | 3.60[3] |
| Characteristics | |
| Evolutionary stage | red clump[4] |
| Spectral type | K0 III[5] |
| B−V color index | +1.07[3] |
| Astrometry | |
| Radial velocity (Rv) | +17.2±0.5[6] km/s |
| Proper motion (μ) | RA: −76.226 mas/yr[2] Dec.: −201.519 mas/yr[2] |
| Parallax (π) | 29.0339±0.2198 mas[2] |
| Distance | 112.3 ± 0.9 ly (34.4 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.89[1] |
| Details | |
| Mass | 1.80[7] M☉ |
| Radius | 10.37±0.09[8] R☉ |
| Luminosity | 58.3±3.0[8] L☉ |
| Surface gravity (log g) | 2.70[3] cgs |
| Temperature | 4,951±64[8] K |
| Metallicity [Fe/H] | −0.13±0.15[3] dex |
| Rotational velocity (v sin i) | 2.60[3] km/s |
| Age | 2.20[7] Gyr |
| Other designations | |
| θ Cet, 45 Cet, BD−08°244, FK5 47, HD 8512, HIP 6537, HR 402, SAO 129274[9] | |
| Database references | |
| SIMBAD | data |
With an age of about 2.2 billion years,[7] this is an evolved, K-type giant star with a stellar classification of K0 III.[5] It is a red clump[4] star on the horizontal branch,[3] which means it is generating energy through helium fusion at its core.[4] The star has an estimated 1.8[7] times the mass of the Sun and has expanded to 10 times the Sun's radius. It is radiating 58 times the solar luminosity from its photosphere at an effective temperature of 4,951 K.[8]
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.[11] 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.[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]