What happens to a small star after burning all of its fuel?

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kelly0303
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Hello! As far as I understand, after a star reaches iron in its core, if it is not massive enough it turns into a white or brown dwarf. What happens when all the energy of the dwarf is gone? Are we left with a huge sphere made almost entirely of iron?
 
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Not many stars get to the Iron production stage, only the biggest as far as I am aware. After the Hydrogen runs out stars start producing helium and only if they have enough mass do they carry on producing heavier and heavier elements after that. Any star big enough to produce Iron will go nova and end up being a neutron star or a stella mass black hole.
 
White dwarfs will, over very long periods of time, cool down until they reach thermal equilibrium with the rest of the universe, which will probably be less than 1 kelvin by the time any white dwarf has had time to cool to that point. They will be large, cold spherical objects composed of carbon, oxygen, and other elements in an extremely dense state.
 
The life time is so long I don't think we have any observation of the end of life of red dwarf stars yet. Brown dwarfs fizzel out after converting deuterium to helium.
Regards Andrew