This
narrow, deep view of the universe reveals a plethora of galaxies (reaching
fainter than 28th magnitude), as seen in visible and infrared light by NASA’s
Hubble Space Telescope. The reddish galaxies are glowing in infrared light,
and the bluish galaxies are glowing in visible light. Several distinctive
types of galaxies can be seen in these views: blue dwarf galaxies, disk
galaxies, and very red elliptical galaxies. A bright, nearby face-on spiral
galaxy appears at upper right. Some of the brightest objects in the field
are foreground stars in the halo of our own Milky Way galaxy. By combining
views in infrared light and visible light astronomers have a better idea
of the shapes of galaxies in the remote universe, and of the fraction which
are old or dust-obscured at early epochs. |
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Galaxies
could appear bright in the infrared (and thus red in this picture) for several
reasons. They might be dusty, or contain old stars, or are at a very great
distance. Several of the red galaxies in this field have the colours and
the smooth, symmetric shapes expected for old elliptical galaxies. The existence
of such objects in the early universe and their numbers can set important
limits on the era when the earliest galaxies assembled and formed most of
their stars. In general, the image shows that the shapes and sizes of most
faint galaxies are similar in infrared and visible light, suggesting that
younger and older stars within distant galaxies are well mixed and that
dust is not completely distorting impressions of distant objects. |
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