The exploding supernova throws the outer layers o dust and gas
into space, leaving a very dense core called a neutron star.
Black Hole
If the star is big enough, it will become a black hole.
Big stars glow brightly gain as they undergo more fusion and expand
several times to make elements as heavy as iron. They eventually
explode to form a supernova.
The star swells into a red giant if its a small star or a red giant if
its a big star. It becomes red because the surface cools.
Red Giant
Planetary Nebula
White Dwarf
Black Dwarf
A white dwarf cools down to a black dwarf and
eventually disappears.
This leaves behind a hot, dense solid core called a white
dwarf.
A small star like the sun becomes unstable and ejects its
outer layer of dust and gas as a planetary nebula.
Eventually the hydrogen begins to run out and heavy elements
such as iron are made by the nuclear fusion of helium.
Gravitational energy is converted to heat - temperature
rises. When the temperature gets high enough, nuclear
fusion occurs, giving out heat and light, forming a star.
The star enters a long, stable period where the heat created provdes
an outward pressure to balance the force of gravity. This period is
called a main sequence star, lasting billions of years.
Stars initially form clouds of dust and gas. The force
of gravity makes the gas and dust spiral in together
to form a protostar.