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Stars and the Universe

Stars  -  Life Cycle - White Dwarf - Black Dwarf.

What is a White Dwarf?

The red giant phase of a small star like the Sun will eventually
change. The star loses some of its gas into space and the
core contracts, gets brighter again and becomes a white dwarf.

A white dwarf, as the name suggests, is very small (for a star).
The mass has contracted so much that it has become very dense,
perhaps one million times as dense as any material on Earth.
A white dwarf does not have nuclear reactions but can be very hot.

What is a Black Dwarf?

In time a white dwarf loses energy, cools down, stops shining
and becomes a black dwarf. A black dwarf can no longer
be seen because it is not emitting any light. It may become
part of what is called "dark matter". It is not known how
much dark matter there is in the universe. Some astronomers
believe that a very large amount of dark matter may exist.

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