Barnard's Star
 The location of Barnard's Star, ca. 2006 (south is up) |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Ophiuchus |
| Pronunciation | /ˈbɑːrnərd/ |
| Right ascension | 17h 57m 48.49803s |
| Declination | +04° 41′ 36.2072″ |
| Apparent magnitude (V) | 9.511 |
| Characteristics | |
| Spectral type | M4.0V |
| Apparent magnitude (U) | 12.497 |
| Apparent magnitude (B) | 11.240 |
| Apparent magnitude (R) | 8.298 |
| Apparent magnitude (I) | 6.741 |
| Apparent magnitude (J) | 5.24 |
| Apparent magnitude (H) | 4.83 |
| Apparent magnitude (K) | 4.524 |
| U−B color index | 1.257 |
| B−V color index | 1.713 |
| Variable type | BY Draconis |
| Astrometry | |
| Radial velocity (Rv) | −110.6 ± 0.2 km/s |
| Proper motion (μ) |
RA: −798.71 mas/yr Dec.: 10337.77 mas/yr |
| Parallax (π) | 545.62 ± 0.2mas |
| Distance | 5.978 ± 0.002 ly (1.8328 ± 0.0007 pc) |
| Absolute magnitude (MV) | 13.21 |
| Details | |
| Mass | 0.144 M☉ |
| Radius | 0.196 ± 0.008 R☉ |
| Luminosity (bolometric) | 0.0035 L☉ |
| Luminosity (visual, LV) | 0.0004 L☉ |
| Temperature | 3,134 ± 102 K |
| Metallicity | 10–32% Sun |
| Rotation | 130.4 d |
| Age | About 10 Gyr |
| Other designations | |
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"Barnard's Runaway Star", "Greyhound of the Skies",BD+04°3561a, GCTP 4098.00, Gl 140-024, Gliese 699, HIP 87937, LFT 1385, LHS 57, LTT 15309, Munich 15040, Proxima Ophiuchi,V2500 Ophiuchi, Velox Barnardi,Vyssotsky 799
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| Database references | |
| SIMBAD | data |
| ARICNS | data |
Barnard's Star /ˈbɑːrnərd/ is a very-low-mass red dwarf about six light-years away from Earth in the constellation of Ophiuchus. It is the fourth-closest known individual star to the Sun (after the three components of the Alpha Centauri system) and the closest star in the Northern Hemisphere. Despite its proximity, at a dim apparent magnitude of about nine, it is not visible with the unaided eye; however, it is much brighter in the infrared than it is in visible light.
The star is named after the American astronomer E. E. Barnard. He was not the first to observe the star (it appeared on Harvard University plates in 1888 and 1890), but in 1916 he measured its proper motion as 10.3 arcseconds per year, which remains the largest proper motion of any star relative to the Solar System.
Barnard's Star is among the most studied red dwarfs because of its proximity and favorable location for observation near the celestial equator. Historically, research on Barnard's Star has focused on measuring its stellar characteristics, its astrometry, and also refining the limits of possible extrasolar planets. Although Barnard's Star is an ancient star, it still experiences star flare events, one being observed in 1998.
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