What does it mean?
Brown dwarf – are cosmic objects that are too small to be stars and too large to be planets. They have the same composition as stars but because of their low mass are unable to sustain nuclear fusion (if they ever manage to get fusion started) at their cores.
Is that all?
Brown Dwarf Detectives – NASA scientists study brown dwarfs.
Brown Dwarfs – A detailed explanation of brown dwarfs.