Despite having a very high surface temperature, why do White Dwarfs exhibit low total luminosity?

Answer

Their minuscule physical size

The low luminosity of a White Dwarf, despite its high temperature, is a direct consequence of its small physical size, which results in a very small surface area from which light is emitted.

Despite having a very high surface temperature, why do White Dwarfs exhibit low total luminosity?
temperaturestarLuminosity