White Dwarf

White Dwarf (Credit:i.ytimg.com)

It is what the Sun becomes when their nuclear fuel is diminished.

A dwarf is intensely dense, the mass can be comparable to the Sun while the size can be of Earth.

The luminosity of this dwarf derived from the emission of stored thermal energy as the fusion has ceased. (Credit:en.wikipedia.org/wiki/White_dwarf & imagine.gsfc.nasa.gov/science/objects/dwarfs2.html)