|Designation|| Gliese 699|
|Right ascension||17h 57m 48.49803s|
|Declination||+04° 41′ 36.2072″|
|Type of object||Red dwarf|
|Magnitude|| Apparent Mag: 9.54|
Absolute Mag: 13.22
|Distance from Earth||5.98 ly|
|Radial velocity||-110.5±0.1 km/s|
|Proper motion|| RA: -798.71 mas/yr|
Dec.: 10337.77 mas/yr
Barnard's Star is a very cool and dim star that is the third closest star to our solar system after Proxima Centauri and Alpha Centauri AB respectively, located some 6 light years from Sol in the constellation of Ophiuchus.
The star was first discovered in 1916 by and then named after American astronomer E. E. Barnard, and like Proxima Centauri is too dim to be viewed by the unaided eye. Barnard noticed in his observations, that the star has the largest known proper motion of all known stars, moving around 10 arcseconds per year. This is due to the star's closeness to our own Solar System and actual travel speed through space. Barnard's Star is approaching our own system at the speed of 140 kilometers per second and will approach as close as 3.8 light years (making it the closest star) around 11,800 A.D. before receding.
Barnard's Star is classified as a spectral type M4.0Ve red dwarf, with only 17 percent of Sol's mass, some 15 to 20 percent of its diameter, but only estimated to have 0.04% of the luminosity of our star. If the Earth orbited Barnard's Star at the same distance as we orbit the sun, the star would be only 100 times more bright then the full moon. The star is relatively inactive, and has a rotation period of only 130.4 days, typical for an older red dwarf star. Barnard's Star however isn't completely inactive, but in 1998 a flare was observed, which scientists believed would be unlikely on such an old star.
In recent history there has been much speculation to whither or not Barnard's Star has any planetary companions. During the late 1960s, astronomer Peter van de Kamp announced the detection of possibly two planets that revolved around each other, however his claim could never be verified, and recent observations have thus far failed to locate any evidence of planetary companions around the star. In order for an Earth-type world to have liquid water at the surface, it would have to be located very close to Barnard's Star, at only around 0.034 to 0.082 AU. Such a world would be tidally locked to the star.
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007). Validation of the new Hipparcos reduction. Astronomy & Astrophysics, 474(2), pp.653-664. arXiv:0708.1752
- ↑ Barnard's Star from the SIMBAD Astronomical Database
- ↑ Koen, C., Kilkenny, D., van Wyk, F. and Marang, F. (2010). UBV(RI)C JHKobservations of Hipparcos-selected nearby stars. Monthly Notices of the Royal Astronomical Society, 403(4), pp.1949-1968.
- ↑ From definition of absolute magnitude, using apparent magnitude (+9.511) and distance (5.98 ly) given here.
- ↑ Nidever, D., Marcy, G., Butler, R., Fischer, D. and Vogt, S. (2002). Radial Velocities for 889 Late‐Type Stars. The Astrophysical Journal Supplement Series, 141(2), pp.503-522. arXiv:astro-ph/0112477
- ↑ Barnard's Star from britanica.com
- ↑ Barnard, E. (1916). A small star with large proper-motion. The Astronomical Journal, 29, p.181. Online
- ↑ Barnard's Star from solstation.com