1 Centauri
1 Centauri, or i Centauri, is a yellow-white-hued binary star system in the southern constellation Centaurus. It can be seen with the naked eye, having an apparent visual magnitude of +4.23. Based upon an annual parallax shift of 51.54 mas as seen from Earth's orbit, it is located 51.5 light-years from the Sun. The system is moving closer to the Sun with a radial velocity of −21.5 km/s.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 45m 41.24482s |
| Declination | −33° 02′ 37.3997″ |
| Apparent magnitude (V) | +4.23 |
| Characteristics | |
| Spectral type | F2 V |
| U−B color index | +0.00 |
| B−V color index | +0.38 |
| Astrometry | |
| Radial velocity (Rv) | −21.5±0.6 km/s |
| Proper motion (μ) | RA: −462.49±0.18 mas/yr Dec.: −146.49±0.16 mas/yr |
| Parallax (π) | 51.54 ± 0.19 mas |
| Distance | 63.3 ± 0.2 ly (19.40 ± 0.07 pc) |
| Absolute magnitude (MV) | +2.81 |
| Orbit | |
| Period (P) | 9.94480±0.00441 d |
| Eccentricity (e) | 0.247±0.105 |
| Periastron epoch (T) | 2,422,737.382 ± 3.35 JD |
| Argument of periastron (ω) (secondary) | 137.7±25.4° |
| Semi-amplitude (K1) (primary) | 6.00±0.75 km/s |
| Details | |
| Mass | 1.35 M☉ |
| Luminosity (bolometric) | 5.857 L☉ |
| Surface gravity (log g) | 4.25±0.14 cgs |
| Temperature | 6,898±235 K |
| Metallicity [Fe/H] | −0.09 dex |
| Rotation | 2.42±0.22 |
| Rotational velocity (v sin i) | 86 km/s |
| Age | 1.193 Gyr |
| Other designations | |
i Centauri, 1 Centauri, CD−32°9603, FK5 506, GC 18593, GJ 525.1, HD 119756, HIP 67153, HR 5168, SAO 204812 | |
| Database references | |
| SIMBAD | data |
Spectrographic images taken at the Cape Observatory between 1921 and 1923 showed this star has a variable radial velocity, which indicated this is a single-lined spectroscopic binary star system. The pair have an orbital period of 9.94 days and an eccentricity of about 0.2.
The primary component has received a number of different stellar classifications. For example, Jaschek et al. (1964) lists F0V, F2III, F4III and F4IV, thus ranging in evolutionary state from an ordinary F-type main-sequence star to a giant star. More recently, Houk (1982) listed a class of F3 V, matching an ordinary main-sequence star that is generating energy through hydrogen fusion at its core. The NStars project gives it a classification of F2 V.