Eta Capricorni
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 21h 04m 24.297s |
| Declination | −19° 51′ 18.33″ |
| Apparent magnitude (V) | +4.84 (5.02 + 7.39) |
| Characteristics | |
| Spectral type | A4 V + F2 V |
| U−B color index | +0.09 |
| B−V color index | +0.17 |
| Astrometry | |
| Proper motion (μ) | RA: −28.702 mas/yr Dec.: −25.294 mas/yr |
| Parallax (π) | 16.6009±0.4965 mas |
| Distance | 196 ± 6 ly (60 ± 2 pc) |
| Absolute magnitude (MV) | +1.35 |
| Orbit | |
| Period (P) | 27.85±0.15 yr |
| Semi-major axis (a) | 0.265±0.003″ |
| Eccentricity (e) | 0.410±0.005 |
| Inclination (i) | 162.6±0.5° |
| Longitude of the node (Ω) | 171.1±15.0° |
| Periastron epoch (T) | 2002.46±0.09 |
| Argument of periastron (ω) (secondary) | 238.2±15.0° |
| Details | |
| η Cap A | |
| Mass | 2.03±0.12 M☉ |
| Luminosity | 24 L☉ |
| Metallicity [Fe/H] | −0.01 dex |
| η Cap B | |
| Mass | 1.21±0.07 M☉ |
| Other designations | |
| η Cap, 22 Cap, BD−20°6115, HD 200499, HIP 104019, HR 8060, SAO 189986, WDS J21044-1951AB | |
| Database references | |
| SIMBAD | data |
Eta Capricorni, Latinized from η Capricorni, is a binary star system in the southern constellation of Capricornus. Its name is a Bayer designation. This system can be seen with the naked eye as a point of light having a combined apparent visual magnitude of +4.84. Based upon an annual parallax shift of 20.20 mas as seen from the Earth, the star is located about 196 light-years (60 pc) from the Sun.
The pair orbit each other with a period of 27.85 years, a semimajor axis of 0.265 arc seconds, and an eccentricity of 0.410. The primary member, component A, is a white-hued A-type main sequence star with an apparent magnitude of +5.02. Its companion, component B, has an apparent magnitude of +7.39.