Barnard's Star is a very low-mass star in the constellation Ophiuchus which was discovered by the astronomer E. E. Barnard in 1916. Barnard measured its proper motion to 10.3 arcseconds per year, which remains the largest known proper motion of any star relative to the Sun. Lying at a distance of about 1.8 parsecs or 5.96 light-years, Barnard's Star is the second closest known star system to the Sun and the fourth closest known individual star after the three components of the Alpha Centauri system.
Barnard's Star is a relatively well-studied astronomical object, and has likely received more attention than any other M dwarf star given its proximity and favourable location for observation near the celestial equator. It has also been the subject of some controversy. For a decade from the early 1960s onward, an erroneous discovery of a planet or planets in orbit around Barnard's star was accepted by astronomers. It is also notable as the target for a study on the possibility of rapid, unmanned travel to nearby star systems. Research has focused on stellar characteristics, astrometry, and refining the limits of possible planets.