Thu, Mar 11, 2004
Space Telescope Finds Farthest Galaxies Yet
Astronomers using the
Hubble Space Telescope (HST) unveiled the deepest look into the
universe yet, a portrait of what could be the most distant galaxies
ever seen. Too bad it won't be around for much longer, as NASA
plans to let the orbiting marvel degrade into a flying piece of
junk. The new image, called the Hubble Ultra Deep Field (HUDF),
includes objects that until now have been too faint to be seen and
includes ancient galaxies that emerged just 700 million years after
the Big Bang from what astronomers call the "dark ages" of the
universe.
"This image is the deepest view in the visible that we've ever
taken, where an object about as bright as a firefly on the Moon
would be visible," said Massimo Stiavelli, of the Space Telescope
Science Institute (STScI) in Baltimore and the UHDF project
leader.
Stiavelli said the new image is six times more sensitive than
previous deep sky surveys and four times better than even Hubble's
last faraway looks, the Hubble Deep Fields (HDFs), taken in 1995
and 1998.
The HUDF field contains an estimated 10,000 galaxies in a patch
of sky in the constellation Fornax, a region just below the
constellation Orion, that appears in an area of the sky that
appears largely empty if observed by ground-based instruments. The
image is about one-tenth the diameter of the full moon and took
Hubble one million seconds to take. To cover the entire sky with
such detail would take the HST one million years, astronomers said.
The HUDF is the result of two separate exposures, one taken by
Hubble's Advanced Camera for Surveys (ACS) and the other by the
Near Infrared Camera and Multi-object Spectrometer (NICMOS).
Astronomers can tell how old a galaxy is by measuring the light it
emits, specifically the amount of light that has been shifted
toward the red end of the spectrum. The higher red shift a galaxy
has, the more distant it is and the earlier it existed in the
universe.
Astronomers are eager to see the Hubble receive a stay of
execution in the form of future servicing missions by NASA's space
shuttles to extend the telescope's lifetime. Adam Riess, a
supernova researcher for STScI, said an extension could help
astronomers find supernova early in the universe's lifetime.
However, NASA Administrator Shawn O'Keefe claims the shuttle fleet
will not be able to participate in HST servicing missions, now that
the panel investigating the 2003 Columbia crash has placed new,
stringent operating restrictions on the orbiter program.
"There are no supernovae in this deep field, but the results show
that supernova in the early universe could be found if Hubble could
be extended," Riess said. "Those could provide valuable insight
into dark energy and fate of the universe."
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