What happens to the temperature of a White Dwarf over billions of years after formation?

Answer

It must cool down

Since a white dwarf no longer generates energy through fusion, it simply radiates away its residual thermal energy, meaning it must cool down over billions of years.

What happens to the temperature of a White Dwarf over billions of years after formation?
astronomytemperaturestarsstellar evolutionwhite dwarfblue giantstar temperature