HD 4747
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 00h 49m 26.76537s |
| Declination | −23° 12′ 44.9359″ |
| Apparent magnitude (V) | 7.155 |
| Characteristics | |
| Spectral type | G8V + L9 |
| B−V color index | 0.769 |
| Astrometry | |
| Radial velocity (Rv) | 9.893 ± 0.016 km/s |
| Proper motion (μ) | RA: 516.92±0.55 mas/yr Dec.: 120.05±0.45 mas/yr |
| Parallax (π) | 53.51±0.53 mas |
| Distance | 61.0 ± 0.6 ly (18.7 ± 0.2 pc) |
| Absolute magnitude (MV) | 5.94 |
| Orbit | |
| Primary | HD 4747A |
| Companion | HD 4747B |
| Period (P) | 33.2±0.4 yr |
| Semi-major axis (a) | 10.0±0.2 AU |
| Eccentricity (e) | 0.7317±0.0014 |
| Inclination (i) | 48.0±0.9° |
| Longitude of the node (Ω) | 89.4±1.1° |
| Periastron epoch (T) | JD 2462615±155 |
| Argument of periastron (ω) (secondary) | 267.2±0.5° |
| Semi-amplitude (K1) (primary) | 0.7553+0.0124 −0.0116 km/s |
| Details | |
| HD 4747A | |
| Mass | 0.85 ± 0.014 M☉ |
| Radius | 0.769 ± 0.016 R☉ |
| Luminosity | 0.45 ± 0.02 (log -0.346 ± 0.04) L☉ |
| Surface gravity (log g) | 4.60 ± 0.15 cgs |
| Temperature | 5400 ± 60 K |
| Metallicity [Fe/H] | -0.23 ± 0.05 dex |
| Rotation | 27.7 ± 0.5 |
| Rotational velocity (v sin i) | 2 ± 1 km/s km/s |
| Age | 2.3 ± 1.4 Gyr |
| HD 4747B | |
| Mass | 67.2 ± 1.8 MJup |
| Other designations | |
| CD−23 315, GJ 36, HIP 3850, SAO 166607 | |
| Database references | |
| SIMBAD | data |
HD 4747 is a star that lies approximately 61 light-years away in the constellation of Cetus. The star is a low-amplitude spectroscopic binary, with the secondary being a directly detected brown dwarf.