From: nasanews
Date: Dec 6 18:47 UTC
Subject: HST Identifies Primeval Galaxy
HUBBLE IDENTIFIES PRIMEVAL GALAXIES, UNCOVERS NEW CLUES TO THE
UNIVERSE'S EVOLUTION
Astronomers using NASA's Hubble Space Telescope as a "time machine"
have obtained the clearest views yet of distant galaxies that existed
when the universe was a fraction of its current age.
A series of remarkable pictures, spanning the life history of the
cosmos, are providing the first clues to the life history of galaxies.
The Hubble results suggest that elliptical galaxies developed
remarkably quickly into their present shapes. However, spiral galaxies
that existed in large clusters evolved over a much longer period -- the
majority being built and then torn apart by dynamic processes in a
restless universe.
Astronomers, surprised and enthusiastic about these preliminary
findings, anticipate that Hubble's observations will lead to a better
understanding of the origin, evolution, and eventual fate of the
universe. The Hubble observations challenge those estimates for the
age of the universe that do not allow enough time for the galaxies to
form and evolve to the maturity seen at an early epoch by the Space
Telescope.
"These unexpected results are likely to have a large influence on our
cosmological models and theories of galaxy formation," says Duccio
Macchetto of the European Space Agency and the Space Telescope Science
Institute (STScI). "These Hubble telescope images are sufficient to
provide a first determination of the properties of these very young and
distant galaxies."
"This is compelling, direct visual evidence that the universe is truly
changing as it ages, as the Big Bang model insists," emphasizes Alan
Dressler of the Carnegie Institutions, Washington, DC. "Though much of
the quantitative work can be done best with large Earth-bound
telescopes, Hubble Space Telescope is providing our first view of the
actual forms and shapes of galaxies when they were young."
"These initial results are surprising," adds Mauro Giavalisco (STScI).
"Hubble is giving us, for the first time, a chance to study in great
detail the properties of very young galaxies and understand the
mechanisms of their formation."
A series of long exposures, taken by separate teams led by Macchetto,
Dressler, and Mark Dickinson (STScI) trace galaxy evolution in rich
clusters that existed when the universe was approximately one-tenth,
one-third, and two-thirds its present age. Their key findings:
* Scientists identified the long-sought population of primeval galaxies
that began to form less than one billion years after the Big Bang.
* One of the deepest images ever taken of the universe reveals a
"cosmic zoo" of bizarre fragmentary objects in a remote cluster that
are the likely ancestors of our Milky Way Galaxy.
* A series of pictures, showing galaxies at different epochs, offers
the most direct evidence to date for dynamic galaxy evolution driven by
explosive bursts of star formation, galaxy collisions, and other
interactions that ultimately created and then destroyed many spiral
galaxies that inhabited rich clusters.
Postcards from Edge of Space and Time
The researchers used Hubble as a powerful "time machine" for probing
the dim past. The astronomical equivalent of digging through geologic
strata on Earth, Hubble peers across a large volume of the observable
universe and resolves thousands of galaxies from five to twelve billion
light-years away. Because their light has taken billions of years to
cross the expanding universe, these distant galaxies are "fossil
evidence," encoded in starlight, of events that happened long ago.
These long-exposure Hubble images will help test and verify ideas about
galaxy evolution based on several decades of conjecture, theoretical
modeling, and ground-based observation. Ground-based observations have
not been able to establish which of several competing theories best
describe how galaxies formed and evolved in the early universe.
Though the largest ground-based telescopes can detect objects at great
distances, only Hubble can reveal the shapes of these remote objects by
resolving structures a fraction of the size of our Milky Way Galaxy.
This is allowing astronomers, for the first time, to discriminate among
various types of distant galaxies and trace their evolution. Like
watching individual frames of a motion picture, the Hubble pictures
reveal the emergence of structure in the infant universe, and the
subsequent dynamic stages of galaxy evolution.
Now that Hubble has clearly shown that it is an exquisite time machine
for seeking our cosmic "roots," astronomers are anxious to push back
the frontiers of time and space even further. "Our goal now is to look
back further than twelve billion years to see what we are sure will be
even more dramatic evidence of galaxies in formation," says Dressler.
The STScI is operated by the Association of Universities for Research
in Astronomy, Inc., for NASA, under contract with the Goddard Space
Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project
of international cooperation between NASA and the European Space
Agency.
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- T o d d E. V a n H o o s e a r -
``'''vanhoose@lalaland.cl.msu.edu - vanhoose@msu.edu - vanhoose@lalaland.cl.msu.edu
(._.) Michigan State University - East Lansing, MI USA
(_) Computer Laboratory - Department of Communication
`---' <A HREF="http://lalaland.cl.msu.edu/~vanhoose/">My Home Page</A>
"I'd love to change the world, but they won't give me the source code!"
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