Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Centaurus |
Right ascension | 13h 53m 12.53953s[1] |
Declination | −31° 55′ 39.3947″[1] |
Apparent magnitude (V) | +4.73[2](+4.72[3] / +8.47[4]) |
Characteristics | |
Spectral type | B6IV[5] / Am[5] |
U−B color index | −0.56[2] |
B−V color index | −0.14[2] |
Astrometry | |
Radial velocity (Rv) | +5.2 ± 2[6] km/s |
Proper motion (μ) | RA: -12.72[1] mas/yr Dec.: -9.48[1] mas/yr |
Parallax (π) | 5.12 ± 0.70 mas[1] |
Distance | approx. 640 ly (approx. 200 pc) |
Absolute magnitude (MV) | −1.66[7] |
Orbit[5] | |
Primary | 4 Cen Aa |
Companion | 4 Cen Ab |
Period (P) | 6.930137 ± 0.000015 |
Eccentricity (e) | 0.25 ± 0.10 |
Periastron epoch (T) | 2418823.406 ± 0.10 |
Argument of periastron (ω) (secondary) | 152 ± 17° |
Semi-amplitude (K1) (primary) | 21.0 ± 1.5 km/s |
Orbit[5] | |
Primary | 4 Cen Ba |
Companion | 4 Cen Bb |
Period (P) | 4.8390 ± 0.0001 |
Eccentricity (e) | 0.05 ± 0.02 |
Periastron epoch (T) | 2442916.55 ± 0.09 |
Argument of periastron (ω) (secondary) | 51 ± 20° |
Semi-amplitude (K1) (primary) | 16.9 ± 3.5 km/s |
Other designations | |
4 Cen A[8]: SAO 204944, GC 18755, CD–31° 10729[9] | |
4 Cen B: SAO 204943, GC 18754, CD–31° 10727[10] | |
Database references | |
SIMBAD | 4 Cen |
4 Cen A | |
4 Cen B |
4 Centauri is a star in the constellation Centaurus. It is a blue-white B-type subgiant with an apparent magnitude of +4.75 and is approximately 640 light years from Earth.
4 Centauri is a hierarchical quadruple star system. The primary component of the system, 4 Centauri A, is a spectroscopic binary, meaning that its components cannot be resolved but periodic Doppler shifts in its spectrum show that it must be orbiting. 4 Centauri A has an orbital period of 6.927 days and an eccentricity of 0.23. Because light from only one of the stars can be detected (i.e. it is a single-lined spectroscopic binary), some parameters such as its inclination are unknown.[11] The secondary component, is also a single-lined spectroscopic binary. It has an orbital period of 4.839 days and an eccentricity of 0.05. The secondary component is a metallic-lined A-type star. The two pairs themselves are separated by 14 arcseconds; one orbit would take at least 55,000 years.[5]