LIFE
OF A STAR
Star Birth - A Nebula
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A nebula is a
cloud of gas (mostly hydrogen) and dust in space.
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Occasionally, a portion
of the nebula collapses causing the matter in its center to become hotter and
denser until nuclear fusion begins.
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Nuclear fusion,
also called ÒburningÓ, is a process that bonds nuclei of atoms , such as H + H
= He.
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This is the birth of a
star.
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The ÒburningÓ of a star
provides all of the light in the universe.
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Planets and moons shine
by reflected light from stars.
Stars are
Different
- Stars
differ in size, color and temperature
Medium Sized
Stars - The Sun
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A medium-sized star,
such as our yellow Sun, will burn for about 10 billion years before it runs out
of fuel for nuclear fusion.
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Towards the end of its
life, the Sun will swell into a red giant, then collapse into a white
dwarf, and finally burn out.
- Nebula
-> Red Giant -> White Dwarf -> Dead Star
Massive Sized
Stars
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Stars more massive than
the Sun have a shorter and different life.
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Towards the end of a
massive starÕs life, it may swell into a red supergiant then supernova.
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A supernova is a
tremendous blast which hurls dust, gas, and elements millions of miles,
sometimes creating a new nebula.
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Ninety-two of our elements
come from supernovas.
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After the supernova of a
massive star a neutron star may remain.
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A neutron star is a small but
incredibly dense star.
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If the neutron star
collapses it can create a black hole.
- Nebula
-> Red Supergiant -> Supernova -> Neutron Star or Black Hole
Black Holes
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A black hole is
so dense and has such intense gravity that nothing can escape, not even light.