Eta Capricorni
Binary star in the constellation Capricornus / From Wikipedia, the free encyclopedia
Eta Capricorni, Latinized from η Capricorni, is a binary star[6] system in the southern constellation of Capricornus. It can be seen with the naked eye, having a combined apparent visual magnitude of +4.84.[2] Based upon an annual parallax shift of 20.20 mas as seen from the Earth,[1] the star is located about 161 light years from the Sun.
Quick Facts Constellation, Right ascension ...
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Capricornus |
Right ascension | 21h 04m 24.30132s[1] |
Declination | −19° 51′ 17.9711″[1] |
Apparent magnitude (V) | +4.84[2] (5.02 + 7.39)[3] |
Characteristics | |
Spectral type | A4 V + F2 V[4] |
U−B color index | +0.09[2] |
B−V color index | +0.17[2] |
Astrometry | |
Proper motion (μ) | RA: −37.62±0.90[1] mas/yr Dec.: −24.95±0.88[1] mas/yr |
Parallax (π) | 20.20 ± 0.82 mas[1] |
Distance | 161 ± 7 ly (50 ± 2 pc) |
Absolute magnitude (MV) | +1.35[5] |
Orbit[6] | |
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[6] M☉ |
Luminosity | 24[5] L☉ |
Metallicity [Fe/H] | −0.01[5] dex |
η Cap B | |
Mass | 1.21±0.07[6] M☉ |
Other designations | |
Database references | |
SIMBAD | data |
Close
The pair orbit each other with a period of 27.85 years, a semimajor axis of 0.265 arc seconds, an eccentricity of 0.410.[6] The primary member, component A, is a white-hued A-type main sequence star with an apparent magnitude of +5.02.[3] Its companion, component B, has an apparent magnitude of +7.39.[3]