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Transcript
Another Example: Expository Mode
stars. Young stars convert hydrogen to helium through a process
known as nuclear fusion to produce light. As stars use up this
hydrogen, in a process that takes billions of years, they pass through
certain phases or stages.
In each stage, the star’s
brightness, temperature,
and size change. The redgiant phase occurs when
the star begins to run out
of hydrogen. Its center
then contracts, and the
temperature and pressure
at the center increase.
However, the star’s outer
layers cool and expand,
increasing the star’s
overall size. Red giants
Betelgeuse, in the constellation Orion, is a
can be anywhere from 10 well-known red-orange giant.
to 100 times the size of the
sun. Most are red, though some may be orange or yellow.
Depending on its overall mass, a red giant may go on to become a
white dwarf or a supergiant.
© The Hampton-Brown Company, Inc.
A. Dupree (CfA), R. Gilland (STScl), FOC, HST, NASA
Red Giants The red-giant phase is a stage in the “life cycle” of