Black dwarf

Low (<1 solar mass) Middle (5-10 solar masses) High (>20 solar masses) Protostar — pre-main sequence — main sequence — red giant — planetary nebula — white dwarf — black dwarf Protostar - main sequence — red giant — planetary nebula or supernova —> white dwarf or neutron star Protostar — main sequence —> supergiant — supernova — neutron star... 

The birth of a protostar and its life as a pre-main-sequence star, its descent to the main sequence and death, starting with a red giant leading to planetary nebula and ending in white and black dwarfs. This sequence varies with mass... 

White dwarf (Earth size) Dead black dwarf... 

White dwarfs Small, hot, white, dim stars, about the size of Earth. Smaller stars (like our Sun) eventually become faint white dwarfs off the Main Sequence. Nuclear fusion no longer occurs, but the stars possess sufficient heat to be visible using telescopes. These hot, shrinking stars have depleted their nuclear fuels and slowly evolve into cold, dark, black dwarfs. The companion of Sirius is a white dwarf. White dwarfs are not visible to the naked eye but are believed to be common, accounting for 10 percent of all stars in the Galaxy. 

Black dwarfs Cooled-off white dwarfs. The final stage in the evolution of stars of roughly one solar mass. Black dwarfs are not massive enough to permit nuclear reactions. 

In stars of small mass (<0.1 times the mass of the sun) the energy liberated by gravitational contraction is not sufficient to reach the temperature necessary to start thermonuclear reactions. These stars are directly entering the stage of black dwarfs (black holes). 

A few protostars are simply too small to "make it as fully evolved stars. The critical point seems to he about 0.08 solar mass. Protostars with less mass than this never develop enough energy in their cores to trigger nuclear reactions. They continue to collapse and emit energy, primarily in the infrared region, hut they do not "ignite" or "shine" the way stars on the Main Sequence do. These stars, known as brown dwarfs, may live up to 15 million years, after which they are unable to contract any further They emit no energy of any kind and they spend the rest of their lives as cold black dwarfs. 

Black Dwarf Imperial Stout o Rhino Porter... 

Black dwarfs are extremely difficult to detect, and because white dwarfs take so long to cool down, it is possible that the universe may not yet be old enough for any black dwarfs to have formed. 

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