Life and Death of Stars
Stars are believed to be formed from the collapse of
large, cold clouds of interstellar matter, mostly of hydrogen gas. the
particles in these clouds are not evenly spread and the closer the particles,
the greater the gravitational pull and the more particles are pulled in. the
core temperature of this mass
eventually reaches millions
of degrees, and become high enough for
nuclear fusion to take place with hydrogen as the fuel. This is what is know as
the birth of the stars.
The mass of a
star determines how long it will remain a main sequence. A star around the size
of the sun would have enough fuel for it to burn for around 10 billion years.
There are larger stars burn hotter and faster and only live for around 1
million years.
Once the hydrogen fuel at the stars core gets used up the
star starts to collapse. At the same time the layers in the outer of the stars.
Eventually the star becomes a red giant, it is large but it is relatively cool.
When a huge star dies in a supernova explosion most of its
gas is blown out into space. A supernova occurs in our galaxy once every 75
years.
Some nebulas emit their own light and they glow like the
stars. The can glow blue, pink yellow or green, this depends on the type of gas
in the cloud.
During supernova explosion astronomers reckon that the
remainder of the stars core is pulled inwards to make it incredibly dense star,
which would be less, then 20kmk in diameter. The protons and electrons in the
core a squeezed so much they join together, this forms neutrons and that is why
they call them neutrons.
These stars don’t glow very brightly but they send out
pulsating radio signals.
Black holes
After a supernova explosion the core of the star collapses
on itself, unlike a smaller star, these big ones keep collapsing. Nothing can
stop the collapse; the gravitational force is so strong it doesn’t even let
light escape from them. The remains of the star is a dark ‘hole’ in space which
astronomers call black holes.
When astronomers get strong x-ray from space they believe
that to be black holes.
