1 Centauri
Yellow-white-hued star in the constellation Centaurus
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1 Centauri, or i Centauri,[11] is a yellow-white-hued binary star[8] system in the southern constellation Centaurus. It can be seen with the naked eye, having an apparent visual magnitude of +4.23.[2] Based upon an annual parallax shift of 51.54 mas as seen from Earth's orbit, it is located 63.3 light-years from the Sun. The system is moving closer to the Sun with a radial velocity of −21.5 km/s.[6]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 45m 41.24482s[1] |
| Declination | −33° 02′ 37.3997″[1] |
| Apparent magnitude (V) | +4.23[2] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | F2 V[4] |
| U−B color index | +0.00[5] |
| B−V color index | +0.38[5] |
| Astrometry | |
| Radial velocity (Rv) | −21.5±0.6[6] km/s |
| Proper motion (μ) | RA: −462.49±0.18[1] mas/yr Dec.: −146.49±0.16[1] mas/yr |
| Parallax (π) | 51.54±0.19 mas[1] |
| Distance | 63.3 ± 0.2 ly (19.40 ± 0.07 pc) |
| Absolute magnitude (MV) | +2.81[7] |
| Orbit[8] | |
| 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[7] M☉ |
| Radius | 1.86[3] R☉ |
| Luminosity (bolometric) | 5.857[9] L☉ |
| Surface gravity (log g) | 4.25±0.14[10] cgs |
| Temperature | 6,898±235[10] K |
| Metallicity [Fe/H] | −0.09[9] dex |
| Rotation | 2.42±0.22[9] |
| Rotational velocity (v sin i) | 86[7] km/s |
| Age | 1.193[10] 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[11] | |
| 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.[8]
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.[12] More recently, Houk (1982) listed a class of F3 V,[13] 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.[4]