Proxima Centauri
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Centaurus |
| Pronunciation | /ˌprɒksɪmə sɛnˈtɔːraɪ/ or US /ˌprɒksɪmə sɛnˈtɔːr.ɪ/ |
| Right ascension | 14h 29m 42.94853s |
| Declination | −62° 40′ 46.1631″ |
| Apparent magnitude (V) | 11.13 |
| Characteristics | |
| Spectral type | M6Ve |
| Apparent magnitude (J) | 5.357 ± 0.023 |
| U−B color index | 1.26 |
| B−V color index | 1.82 |
| Variable type | UV Ceti ("flare star") |
| Astrometry | |
| Radial velocity (Rv) | −22.4 ± 0.5 km/s |
| Proper motion (μ) |
RA: −3775.75 mas/yr Dec.: 765.54 mas/yr |
| Parallax (π) | 768.13 ± 1.04mas |
| Distance | 4.246 ± 0.006 ly (1.302 ± 0.002 pc) |
| Absolute magnitude (MV) | 15.60 |
| Details | |
| Mass | 0.123 ± 0.006 M☉ |
| Radius | 0.141 ± 0.007 R☉ |
| Luminosity (bolometric) | 0.0017 L☉ |
| Luminosity (visual, LV) | 0.00005 L☉ |
| Surface gravity (log g) | 5.20 ± 0.23 cgs |
| Temperature | 3,042 ± 117 K |
| Metallicity [Fe/H] | 0.21 dex |
| Rotation | 82.6±0.1 days |
| Rotational velocity (v sin i) | < 0.1 km/s |
| Age | 4.85 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Coordinates: 
14h 29m 42.9487s, −62° 40′ 46.141″
Proxima Centauri (from Latin, meaning "nearest [star] of Centaurus") or Alpha Centauri C is a red dwarf, a small low-mass star, about 4.25 light-years from the Sun in the constellation of Centaurus. It was discovered in 1915 by the Scottish astronomer Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest-known star to the Sun. With an apparent magnitude of 11.05, it is too faint to be seen with the naked eye. Proxima Centauri may form a third component of the Alpha Centauri binary star system, but at a separation of 15,000 ± 700AU its orbital period is likely greater than 500,000 years.
Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. It is about one-seventh the diameter of the Sun. It has a mass about an eighth of the Sun's mass (M☉), and its average density is about 40 times that of the Sun. Although it has a very low average luminosity, Proxima is a flare star that undergoes random dramatic increases in brightness because of magnetic activity. The star's magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The mixing of the fuel at Proxima Centauri's core through convection and its relatively low energy-production rate mean that it will be a main-sequence star for another four trillion years, or nearly 300 times the current age of the universe.
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