The pair of newly found stars is the closest star system discovered since 1916.
Both stars in the new binary system discovered by NASA's Wide-field Infrared Survey Explorer (WISE) are "brown dwarfs", which are stars that are too small in mass to ever become hot enough to ignite hydrogen fusion.
As a result, they 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," said Kevin Luhman, an associate professor of astronomy and astrophysics at Penn State University, University Park, and a researcher in Penn State's Center for Exoplanets and Habitable Worlds.
More From This Section
The star system is named "WISE J104915.57-531906" because it was discovered in an infrared map of the entire sky obtained by WISE.
It is only slightly farther away than the second-closest star, Barnard's star, which was discovered 6 light-years from the Sun in 1916.
The closest star system consists of: Alpha Centauri, found to be a neighbour of the Sun in 1839 at 4.4 light-years away, and the fainter Proxima Centauri, discovered in 1917 at 4.2 light-years.
The study will be published in Astrophysical Journal Letters.