Global InformationEta Gruis information
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Grus |
| Right ascension | 22h 45m 37.88285s[1] |
| Declination | −53° 30′ 00.4405″[1] |
| Apparent magnitude (V) | 4.85[2] |
| Characteristics | |
| Spectral type | K2 III CNIV[3] |
| U−B color index | +1.17[2] |
| B−V color index | +1.18[2] |
| Astrometry | |
| Radial velocity (Rv) | +27.8±2.8[4] km/s |
| Proper motion (μ) | RA: +30.207[1] mas/yr Dec.: +17.921[1] mas/yr |
| Parallax (π) | 7.1001 ± 0.1924 mas[1] |
| Distance | 460 ± 10 ly (141 ± 4 pc) |
| Absolute magnitude (MV) | −0.68[5] |
| Details | |
| Radius | 31.38+0.92 −1.04[1] R☉ |
| Luminosity | 338.5±10.5[1] L☉ |
| Temperature | 4,420+75 −64[1] K |
| Other designations | |
η Gru, CPD−54° 10123, FK5 3821, HD 215369, HIP 112374, HR 8655, SAO 247570, WDS J22456-5330A[6] | |
| Database references | |
| SIMBAD | data |
Eta Gruis, Latinized from η Gruis, is a solitary[7] star in the southern constellation of Grus. It is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 4.85.[2] Based upon an annual parallax shift of 7.1 mas as seen from the Earth,[8] the system is located about 460 light years from the Sun. The star is drifting further away with a radial velocity of +28 km/s.[4]
This object is an evolved K-type giant star with a stellar classification of K2 III CNIV,[3] where the suffix notation indicates this is an intermediate CN star. It is a periodic microvariable with an amplitude of 0.0055 magnitude and a frequency of 0.36118 cycles per day.[9] With the supply of hydrogen exhausted at its core, the star has expanded and cooled, now having 31[1] times the Sun's girth. It is radiating 338.5[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,420 K.[1]
Eta Gruis has a magnitude 11.5 visual companion located at an angular separation of 25.6″ along a position angle of 187°, as of 2012.[10]
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