Dusting Spiral Galaxies
How much dust is in spiral galaxies?
Does it block out much of the starlight?
Because astronomers rely on an accurate knowledge
of galaxy properties
to investigate a wide range of problems, like galaxy and
quasar evolution and the
nature of dark matter, answers to simple questions like this
are key.
This striking,
detailed Hubble Space Telescope image of dust in the outer reaches
of a foreground spiral galaxy
(left) back lit by an elliptical galaxy offers
an elegant approach to providing the answers.
As expected, dust lanes in the foreground galaxy seem to be associated
with spiral arms.
But surprisingly, many dust regions are not
completely opaque and the dust is more smoothly distributed
than anticipated.
This "overlapping" pair of galaxies is cataloged as AM1316-241 and is about
400 million light-years away in
the constellation Hydra.