HUDF: Dawn of the Galaxies
When did galaxies form?
Faint red smudges identified on the
deepest optical sky image
ever taken may well be members of the first class of galaxies.
Detailed inspection of the
Hubble Ultra Deep Field (HUDF), taken by the
Advanced Camera for Surveys
on the
Hubble Space Telescope,
found the galaxies, circled above, and used their distance and abundance to
probe the universe
when it was only a few percent of its present age.
Analyses indicate that the discovered class of galaxies is exclusively composed of these smaller
dwarf galaxies from which larger
modern galaxies must have formed.
Some large modern galaxies make a colorful foreground to the above
HUDF.
The first class of dwarf galaxies likely contained
energetic stars emitting light that
transformed much of the remaining
normal matter in the universe from a cold gas to a hot
ionized plasma.