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Why do stars shine?
Name: martin lapinski
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1993 - 1999
Question:
Why do stars shine?
Replies:
Stars get their heat from two sources - gravity, and
nuclear fusion. When stars initially form from large balls
of gas, they contract under the influence of gravity, and
heat up because that gravitational energy goes into the
motion of the gas. Once they get hot enough, the hydrogen
nuclei in the plasma in the center of the star start to
occasionally merge to form helium, releasing a lot of energy
from that nuclear fusion process. All this heating, from
both sources, creates a pressure that causes the star to
quit contracting at some point. If the star is big enough to
start with, the central temperature will be high enough to
really keep that fusion going, and the heat gradually will
seep out to the outside parts of the star, so the outer
surface regions will also rise to quite high temperatures.
It is the temperature of the outer surface that determines the
way the stars shine - our sun has an outer temperature of around
5000 degrees, but other stars can be as hot as 50,000 degrees,
producing much bluer light, while red dwarf stars are considerably
cooler and produce mostly red and infrared light.
A Smith
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Update: June 2012
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