Eta Ceti
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 01h 08m 35.39133s |
| Declination | −10° 10′ 56.1519″ |
| Apparent magnitude (V) | +3.446 |
| Characteristics | |
| Evolutionary stage | Red-giant branch |
| Spectral type | K2−IIIb |
| U−B color index | +1.194 |
| B−V color index | +1.161 |
| Astrometry | |
| Radial velocity (Rv) | +11.74±0.30 km/s |
| Proper motion (μ) | RA: +215.922 mas/yr Dec.: −139.029 mas/yr |
| Parallax (π) | 27.0603±0.1799 mas |
| Distance | 120.5 ± 0.8 ly (37.0 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.68 |
| Details | |
| Mass | 1.7±0.1 M☉ |
| Radius | 13.2±0.1 R☉ |
| Luminosity | 74.0±3.7 L☉ |
| Surface gravity (log g) | 2.5 cgs |
| Temperature | 4,543±24 K |
| Metallicity [Fe/H] | −0.03 dex |
| Rotational velocity (v sin i) | 4.8 km/s |
| Age | 1.80 Gyr |
| Other designations | |
| Deneb Algenubi, Algenudi, 31 Ceti, BD−10 240, FK5 40, HD 6805, HIP 5364, HR 334, SAO 147632, 2MASS J01083539-1010560 | |
| Database references | |
| SIMBAD | data |
Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of 120.5 light-years (36.9 parsecs).
This is a giant star that has been chosen a standard for the stellar classification of K2−IIIb. It has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a strong CN star with higher-than-normal abundance of cyanogen and iron relative to other stars of its class.) It is probably on the red giant branch fusing hydrogen in a shell, although there is a possibility that it is a red clump star that is generating energy through the nuclear fusion of helium at its core.
Eta Ceti has 1.7 times more mass than the Sun and its surface has expanded to 13 times the Sun's radius. It is radiating 74 times as much luminosity as the Sun from its photosphere at an effective temperature of 4,356 K. This heat gives the star the orange-hued glow of a K-type star.