What is a brown dwarf?

A brown dwarf is like a star, only it is so small that it can’t quite work up the energy to shine as stars do. Brown dwarfs are at the lower end of the stellar family and are somewhere between the faint hydrogen-burning stars and the giant planets such as Jupiter. Stars vary considerably in size depending on where they were formed. Most are just a little smaller than our Sun, although some can be enormous. There is a limit, however, to how small a star can be in order to achieve the nuclear fusion that drives all stars. If a star is smaller than the minimum, it will glow dull red, a color that comes from its pressurized gases. This is how the brown dwarf was named. Because brown dwarfs are so small and dim, they have only recently been detected by astronomers with the help of infrared telescope technology.