Explanation:
How can a round star make a square nebula?
This conundrum comes to light when studying
planetary nebulae like IC 4406.
Evidence indicates that
IC 4406 is likely a hollow cylinder,
with its square appearance the result of our vantage point in viewing the
cylinder from the side.
Were IC 4406
viewed from the top, it would likely look similar to the
Ring Nebula.
This representative-color picture is a
composite made by combining
images taken by the
Hubble Space Telescope in 2001 and 2002.
Hot gas flows out the ends of the cylinder, while filaments of dark
dust and
molecular gas
lace the bounding walls.
The star primarily responsible for this
interstellar sculpture can be found in the
planetary nebula's center.
In a few million years, the only thing left visible in
IC 4406 will be a fading
white dwarf star.
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