Chandra’s observation of TWA 5 distinguished the brown dwarf TWA 5B from TWA 5A. The X-rays from both the stars and the brown dwarf come from their hot upper atmospheres, or coronas. The interiors of young stars and brown dwarfs are turbulent. When combined with rapid rotation, this turbulence can lead to a tangled magnetic field that can heat their upper atmospheres, or coronas, to a few million degrees Celsius. TWA 5B is estimated to be only between 15 and 40 times the mass of Jupiter, making it one of the least massive brown dwarfs known.