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The various stages of a star's life, from its beginnings as a protostar in a stellar nebula to its eventual demise as a white dwarf, black dwarf, or black hole. The document also discusses the differences between main sequence stars, red giants, red supergiants, and supernovae.
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^ All^ stars^ follow^ a^ very
specific^ life
cycle.
^ All^ stars^ begin^ in^ the
same^ way. ^ The^ size^
of^ the^ star^
determines
how^ the^ star
will
“die.” All^ stars^ begin
their^ lives^ in^ a^ stellar^
nebula^ as^ cool
clouds^ of^ gas
and^ dust. ^ Once^ the
cloud^ of^ gas
and^ dust^ begins
collapsing in
on^ itself,^ it^
becomes^ a
protostar.
^ The next stage of a star’s life is called
Main
Sequence Main sequence stars are stars, like our Sun, that fusehydrogen atoms together to make helium atoms intheir cores. Since stars have a limited supply of hydrogen in theircores, they have a limited lifetime as main sequencestars. The amount of mass and the luminosity, or brightnessof stars, determines the length of their lives.
^ Stars^ the
size^ of^ our
sun^ or^ smaller
become^ red
giants. As^ hydrogen
in^ the^ core
is^ consumed,
the^ core^ of
the^ star^ loses
gravity. ^ Eventually,
the^ outer^ parts
of^ the^ star
expand^ away
from^ the^ core
and^ its^ decreased
gravity.
^ Red^ giants
eventually
become^ planetary
nebula
where^ the^ outer
layers^ of^ the
star^ are^ blown
away
leaving^ only
the^ hot,^ dense
core
^ After^ becoming
a^ planetary
nebula,^ the
remains^ of
the^ core^ of
the^ star^ become
a^ white^ dwarf. ^ A^ white^ dwarf
is^ a^ star^ that
has^ exhausted
most^ or
all^ of^ its^ nuclear
fuel^ and^ has
collapsed^ to
a^ very
small^ size;^
such^ a^ star is^ near^ its^ final
stage^ of^ life.
^ White^ dwarfs
eventually
become^ black
dwarfs,
which^ is^ a^ white
dwarf^ that
has^ cooled
down^ enough
that^ it^ no^ longer
emits^ light. ^ Interesting
Fact:^ The^ universe
is^ not^ old^ enough
to
have^ any^ black
dwarf^ stars
yet.
^ Eventually
Red^ Super
Giants^ will
explode^ in
something
called^ a^ Supernova. ^ A supernova occurs when a star withmany times the mass of the Sun runs outof usable nuclear fuel. ^ The^ Crab Nebula
is an example of the remnants of supernova.
^ Neutron stars^ are^ the
collapsed^ cores
of^ some
massive^ stars.
They^ pack roughly^ the
mass^ of^ our
Sun^ into^ a^ region
the^ size^ of
a^ city. ^ Black^ Holes
form^ from
the^ most^ massive
of^ stars.
^ Black^ holes
have^ such^
strong^ gravity
that^ nothing,
not^ even^ light,
can^ escape
their^ grip.