Penn State astronomy and astrophysics Professor Kevin Luhman, who made the discovery in star surveys conducted by the NASA-funded WISE satellite that was confirmed by ground telescopes, said the stars are "brown dwarfs," stars too small in mass to become hot enough to ignite hydrogen fusion.
Such stars are very cool and dim, resembling a giant planet like Jupiter more than a bright star like the sun.
"The distance to this brown dwarf pair is 6.5 light-years -- so close that Earth's television transmissions from 2006 are now arriving there," Luhman said in a Penn State release Monday.
The new star system, dubbed WISE 1049-5319 is only slightly farther away than the second-closest star, Barnard's star, discovered 6.0 light-years from the sun in 1916. The closest star system consists of Alpha Centauri, found in 1839 at 4.4 light-years and the fainter Proxima Centauri, discovered in 1917 at 4.2 light-years.
The close proximity of the system makes it an ideal candidate for the search for planets outside the solar system, Luhman said.
"It will be an excellent hunting ground for planets because it is very close to Earth, which makes it a lot easier to see any planets orbiting either of the brown dwarfs," he said.