The hot, dense core of a once-normal star like the Sun. At the end of such a star's life, it can no longer produce the nuclear-fusion reactions that power it. Its outer layers drift away into space, while its core collapses into a ball that is as about as massive as the Sun but no bigger than Earth. This is the fate of stars that do not exceed about four to eight times the mass of the Sun. The Sun reaches this stage in a few hundred million to several billion years, depending on the star's original mass. A white dwarf may spin rapidly, is extremely hot, and may generate a strong magnetic field.