third nearest star to the Sun (after Proxima Centauri and Alpha Centauri’s A and B components considered together), at a distance of about 6 light-years. It is named for Edward Emerson Barnard, the American astronomer who discovered it in 1916. Barnard’s star has the largest proper motion of any known star—10.25 seconds of arc annually. It is a red dwarf star with a visual magnitude of 9.5; its intrinsic luminosity is only 1/2,600 that of the Sun.
Because of its high velocity of approach, 108 km (67 miles) per second, Barnard’s star is gradually coming nearer the solar system and by the year 11,800 will reach its closest point in distance—namely, 3.85 light-years. The star is of special interest to astronomers because its proper motion, observed photographically between the years 1938–81, was thought to show periodic deviations of 0.02 seconds of arc. This “perturbation” was interpreted as being caused by the gravitational pull of two planetary companions having orbital periods of 13.5 and 19 years, respectively, and masses of about two-thirds that of Jupiter. However, this finding has not been supported by results from other methods of detection.
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