The Sun's neighbourhood is a little more crowded than we realized. Astronomers have discovered two ultracool brown dwarfs around 5 parsecs away — just four times farther than the distance to our next-nearest star, Proxima Centauri.

Brown dwarfs are objects bigger than Jupiter, but not big enough for their gravity to ignite fusion, as in a star. Ralf-Dieter Scholz and his colleagues at the Leibniz Institute for Astrophysics in Potsdam, Germany, found the brown dwarfs using NASA's Wide-field Infrared Survey Explorer. They looked for objects that had moved a lot in the sky since two previous ground-based surveys, indicating that these objects are close to us.

Astron. Astrophys. 532, L5 (2011)