  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Corona Borealis |
| Right ascension | 15h 23m 12.31s[1] |
| Declination | +30° 17′ 16.17″[1] |
| Apparent magnitude (V) | 5.02 |
| Characteristics | |
| Spectral type | G1V[2] / G3V[2] / L8 [3] |
| B−V color index | 0.56 |
| Astrometry | |
| Radial velocity (Rv) | -7.410 ± 0.054[4] km/s |
| Proper motion (μ) | RA: 116.83 ± 0.40[1] mas/yr Dec.: -171.37 ± 0.49[1] mas/yr |
| Parallax (π) | 55.98 ± 0.78 mas[1] |
| Distance | 58.3 ± 0.8 ly (17.9 ± 0.2 pc) |
| Orbit[4] | |
| Primary | Eta Coronae Borealis A |
| Companion | Eta Coronae Borealis B |
| Period (P) | 15189.1 ± 2.9 days |
| Semi-major axis (a) | 0.860 ± 0.003″ |
| Eccentricity (e) | 0.277 ± 0.001 |
| Inclination (i) | 58.7 ± 0.16° |
| Longitude of the node (Ω) | 22.9 ± 0.19° |
| Periastron epoch (T) | 1892.317 ± 0.031 |
| Argument of periastron (ω) (secondary) | 39.24 ± 0.37° |
| Argument of periastron (ω) (primary) | 219.2 ± 0.37° |
| Semi-amplitude (K1) (primary) | 4.709 ± 0.095 km/s |
| Semi-amplitude (K2) (secondary) | 5.276 ± 0.054 km/s |
| Position (relative to Eta Coronae Borealis AB)[3] | |
| Component | Eta Coronae Borealis C |
| Angular distance | 194″ |
| Position angle | 136° |
| Projected separation | ~3600 AU |
| Details | |
| A | |
| Mass | 1.19 ± 0.071[4] M☉ |
| Metallicity [Fe/H] | -0.20[5] dex |
| Age | 1-2.5[3] Gyr |
| B | |
| Mass | 1.05±0.05[4] M☉ |
| Age | 0.5 to 10[6] Gyr |
| C | |
| Mass | 63±16[3] MJup |
| Radius | 0.97±0.11[6] RJup |
| Luminosity | 2.667×10−5[6] L☉ |
| Temperature | 1295±76[6] K |
| Other designations | |
2 Coronae Borealis, HD 137107/137108, HIP 75312, Gliese 584, HR 5727 | |
| Database references | |
| SIMBAD | data |
Eta Coronae Borealis (η Coronae Borealis, η CrB) is a stellar system that lies approximately 58 light-years away. The primary component is a mid-wide binary, while a brown dwarf component is located at a wide separation.
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