Red Giant
Red Giant
Red giants are the
ending stages of a star which has exhausted all its hydrogen at its core and
has started to consume the hydrogen from its outer shell. Only the stars with
smaller mass i.e. 0.3 to 8 solar masses become red giant at the end of its
life.
When the hydrogen in
the inner core of the star is fully consumed then the nuclear fusion reaction
starts shifting in the outer shells. When the outermost shells of the star
start burning, then the core contracts due to its own gravity. This creates an
empty space between the core and the outer shell. The outer shell of the star
keeps expanding. This expansion is so massive that its radius becomes 100 times
bigger than the radius of our sun. Though the core doesn’t burn, even then it
is hotter than the expanding shell. The outer shell radiates lesser energy than
our sun still it is much brighter because of its extra-large size. The surface
temperature of this outer envelope is low, that is why it appears reddish
orange in color. Its life is too short as compare to its life as a normal star
and as the time passes, the core contracts more and the envelope
expands. When this expansion exceeds its limit, it explodes leaving behind a
fade cloud of dust and a core without any activity.
The stars which are
larger than 8 solar masses don’t convert into a red giant as their
gravitational pull is too high to allow any expansion in the outer shell. Stars
with a very high mass simply become a black hole.
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