 The name "black dwarf" has also been applied to hypothetical late-stage cooled brown dwarfs – substellar objects that do not have sufficient mass (less than approximately 0.08 ) to maintain hydrogen-burning nuclear fusion.Black dwarfs should not be confused with black holes or black stars.A white dwarf is what remains of a main-sequence star of low or medium mass (below approximately 9 to 10 solar masses ()) after it has either expelled or fused all the elements for which it has sufficient temperature to fuse.