Black Dwarfs are still theoretical bodies in the Universe.
Belief and scientific observations are two different things. In theory, they will exist, but until one is observed, there existence can not be confirmed.
See related question
According to astronomers and authors Jonathan Weiner and Carl Sagan, white dwarfs - which have been an accepted entities by all astronomers for decades - require an amount of time to "cool down" that well exceeds the current age of the universe - hence there hasn't been enough time for any of them to cool down yet and become "black dwarfs".
None of the above. White dwarfs and the black dwarfs they will become consist of a unique state of matter called electron degenerate matter.
I think white dwarfs. This is because they are much more low mass than black holes. White dwarfs are much more common in the universe than black holes, because we have only discovered a few black holes whereas we are aware of many white dwarfs.
No.
There are currently no black dwarfs. The time it would take for a white dwarf to cool to a black dwarf is greater than the current age of the universe.
According to astronomers and authors Jonathan Weiner and Carl Sagan, white dwarfs - which have been an accepted entities by all astronomers for decades - require an amount of time to "cool down" that well exceeds the current age of the universe - hence there hasn't been enough time for any of them to cool down yet and become "black dwarfs".
They don't.
None of the above. White dwarfs and the black dwarfs they will become consist of a unique state of matter called electron degenerate matter.
their colour is one thing but a black dwarf originates from a white dwarf
specifically, "astronomers" that study black holes are called cosmologists.
Astronomers believe that black holes exist in the center of every universe. They even think that there may be a black hole in the center of our galaxy, the Milky Way
Black dwarfs of black holes.
A sphere.
Astronomers believe that there are black holes, but I will add that they have only been observed indirectly at great distances, so it may be that the interpretation of our observations will change in the future.
I think white dwarfs. This is because they are much more low mass than black holes. White dwarfs are much more common in the universe than black holes, because we have only discovered a few black holes whereas we are aware of many white dwarfs.
Earth
Stars.