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a small planetary nebula Size is only approximate. False color.
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A planetary nebula represents the final stage in the evolution of a
star similar to our Sun. The star at the center of IC 418 was a red
giant a few thousand years ago, but then ejected its outer layers
into space to form the nebula, which has now expanded to a diameter
of about 0.1 light-year. The stellar remnant at the center is the
hot core of the red giant, from which ultraviolet radiation floods
out into the surrounding gas, causing it to fluoresce. Over the
next several thousand years, the nebula will gradually disperse into
space, and then the star will cool and fade away for billions of
years as a white dwarf. Our own Sun is expected to undergo a similar
fate, but this will not occur until some 5 billion years from now.
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