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94_52.txt
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1994-12-13
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CONTACT: Ray Villard, STScI EMBARGOED UNTIL: 1:00 PM (EST)
(410) 338-4514 Tuesday, December 6, 1994
Duccio Macchetto, STScI PRESS RELEASE NO.: STScI-PR94-52
(410) 338-4790
Alan Dressler, Carnegie Institutions of Washington
(818) 304-0245
Mark Dickinson, STScI
(410) 338-4992
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 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, D.C. "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, which 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 Space Telescope Science Institute (STScI) is operated by the
Association of Universities for Research in Astronomy, Inc. (AURA)
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 (ESA).
* * * * * *
NASA press releases and other information are available automatically
by sending an Internet electronic mail message to domo@hq.nasa.gov.
In the body of the message (not the subject line) users should type
the words "subscribe press-release" (not quotes). The system will
reply with a confirmation via E-mail of each subscription. A second
automatic message will include additional information on the service.
Questions should be directed to (202) 358-4043.
To electronically access this press release and associated captioned
images and background information, you can use the Internet or
World Wide Web.
Image files are on ftp.stsci.edu in the directory /stsci/epa/gif:
PR# GIF file Caption text
STScI-PRC94-52a GalaxEvA.gif GalaxEvA.txt
STScI-PRC94-52b GalaxEvB.gif GalaxEvB.txt
STScI-PRC94-52c GalaxEvC.gif GalaxEvC.txt
STScI-PRC94-25 GalaxEvD.gif GalaxEvD.txt
The press release text is in the file /stsci/epa/press-releases/94-52.
The same data is available using WWW/Mosaic, which is always
accessible via:
http://www.stsci.edu/EPA/OPO.html
or to get right to the latest release:
http://www.stsci.edu/EPA/OPO/Latest.html