Black dwarf

A black dwarf is a kind of star. A black dwarf is made when a white dwarf star becomes too cold. When it is cold enough, it can no longer make large amounts of heat and light. The star will get darker and become black. Scientists are not certain if black dwarfs can exist because it takes longer than the age of the universe (13.8 billion years) for a white dwarf to become one.
Formation.
A white dwarf is made from a medium or small-sized star (any star less than nine or ten times the size of the sun) when it uses all of its fuel. After the star uses its fuel, it is a very tight ball of gasses. Then, it gets colder and colder, until it stops making light and heat, when it becomes a black dwarf. Scientists are not sure how long this takes. Some think it takes 1,000,000 billion years, but others think it could be longer. Scientists do not believe that black dwarf stars can exist right now because the universe is only 13.8 billion years old.