4 Centauri
Star in the constellation Centaurus
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4 Centauri is a multiple star in the constellation Centaurus, approximately 640 light years from Earth. It has a combined apparent magnitude of +4.71.[18] The primary is a blue-white B-type subgiant with a spectroscopic companion, while the secondary is an Am star also with a spectroscopic companion.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus[1] |
| A | |
| Right ascension | 13h 53m 12.53829s[2] |
| Declination | −31° 55′ 39.4304″[2] |
| Apparent magnitude (V) | +4.72[3] |
| B | |
| Right ascension | 13h 53m 12.43506s[4] |
| Declination | −31° 55′ 54.1506″[4] |
| Apparent magnitude (V) | +8.47[5]) |
| Characteristics | |
| A | |
| Evolutionary stage | main sequence[2] |
| Spectral type | B6IV[6] |
| U−B color index | −0.56[7] |
| B−V color index | −0.14[7] |
| B | |
| Evolutionary stage | main sequence[4] |
| Spectral type | Am[6] |
| U−B color index | +0.10[8] |
| B−V color index | +0.30[8] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | +5.2±2[9] km/s |
| Proper motion (μ) | RA: −10.428[2] mas/yr Dec.: −10.710[2] mas/yr |
| Parallax (π) | 4.8225±0.1539 mas[2] |
| Distance | 680 ± 20 ly (207 ± 7 pc) |
| Absolute magnitude (MV) | −1.66[1] |
| B | |
| Radial velocity (Rv) | +9±10[9] km/s |
| Proper motion (μ) | RA: −10.905[4] mas/yr Dec.: −10.625[4] mas/yr |
| Parallax (π) | 4.1269±0.1312 mas[4] |
| Distance | 790 ± 30 ly (242 ± 8 pc) |
| Orbit[6] | |
| Primary | 4 Cen Aa |
| Name | 4 Cen Ab |
| Period (P) | 6.930137±0.000015 d |
| Eccentricity (e) | 0.25±0.10 |
| Argument of periastron (ω) (secondary) | 152±17° |
| Semi-amplitude (K1) (primary) | 21.0±1.5 km/s |
| Orbit[6] | |
| Primary | 4 Cen Ba |
| Name | 4 Cen Bb |
| Period (P) | 4.8390±0.0001 d |
| 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 |
| Details | |
| Aa | |
| Mass | 7.7[10] M☉ |
| Radius | 6.2[2] R☉ |
| Luminosity | 687[11] L☉ |
| Surface gravity (log g) | 3.43[2] cgs |
| Temperature | 14,322[11] K |
| Metallicity [Fe/H] | −1.06[2] dex |
| Rotation | 27.2 days[12] |
| Age | 51[13] Myr |
| Ab | |
| Mass | 0.75[10] M☉ |
| Details | |
| Ba | |
| Mass | 1.9[10] M☉ |
| Radius | 2.48[14] R☉ |
| Luminosity | 17.0[14] L☉ |
| Surface gravity (log g) | 3.88[14] cgs |
| Temperature | 7,440[14] K |
| Bb | |
| Mass | 0.22[10] M☉ |
| Other designations | |
| h Cen, 4 Cen, HD 120955, HR 5221, CCDM J13532-3156[15] | |
| A: CD−31°10729, GC 18755, HIP 67786, SAO 204944[16] | |
| B: CD−31°10727, GC 18754, SAO 204943[17] | |
| Database references | |
| SIMBAD | data |
| 4 Cen B | |
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.[19] 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.[6]