New View of Distant Galaxy Reveals Furious Star Formation (Forwarded)

Public Affairs Office
Harvard-Smithsonian Center for Astrophysics

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462

Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463

For Release: Tuesday, December 18, 2007

Release No.: 2007-33

New View of Distant Galaxy Reveals Furious Star Formation

Cambridge, MA -- A furious rate of star formation discovered in a distant
galaxy shows that galaxies in the early universe developed either much
faster or in a different way from what astronomers have thought.

"This galaxy is forming stars at an incredible rate," said Wei-Hao Wang, an
astronomer at the National Radio Astronomy Observatory (NRAO) in Socorro,
New Mexico. The galaxy, Wang said, is forming the equivalent of 4,000 Suns a
year. This is a thousand times more violent than our own Milky Way galaxy.

The galaxy, called GOODS 850-5, is 12 billion light-years from Earth, and
thus is seen as it was only about 1.5 billion years after the Big Bang. Wang
and his colleagues observed it using the Smithsonian Astrophysical
Observatory's Submillimeter Array (SMA) on Mauna Kea in Hawaii.

Young stars in the galaxy were enshrouded in dust that was heated by the
stars and radiated infrared light strongly. Because of the galaxy's great
distance from Earth, the infrared light waves have been stretched out to
submillimeter-length radio waves, which are seen by the SMA. The waves were
stretched or "redshifted," as astronomers say, by the ongoing expansion of
the Universe.

"This evidence for prolific star formation is hidden by the dust from
visible-light telescopes," Wang explained. The dust, in turn, was formed
from heavy elements that had to be built up in the cores of earlier stars.
This indicates, Wang said, that significant numbers of stars already had
formed, then spewed those heavy elements into interstellar space through
supernova explosions and stellar winds.

"Seeing the radiation from this heated dust revealed star formation we could
have found in no other way," Wang said. Similar dusty galaxies in the early
universe may contain most of the star formation at those times. "This means
that future telescopes such as the Atacama Large Millimeter Array (ALMA) can
reveal many more such galaxies and give us a much more complete picture of
star formation in the early universe," he added.

Lennox Cowie of the University of Hawaii said, "We found out in the last
decade that most of the recent star formation in the Universe occurs in
large dusty galaxies, but we had always expected that early star formation
would be dominated by smaller and less obscured galaxies. Now it seems that
even at very early times it may be the same big dusty star formers that are
the sites of most of the star formation. That's quite a surprise."

Astronomers believe that large galaxies originally formed through mergers of
smaller objects. Seeing a large galaxy such as GOODS 850-5 forming stars so
rapidly at such an early time in the history of the universe is a surprise.
"Either the mergers that formed the galaxy happened much faster than we
thought or some other process altogether produced the galaxy," Wang said.

Wang and Cowie worked with Jennifer van Saders of Rutgers University and
NRAO, Amy Barger of the University of Wisconsin-Madison, and Jonathan
Williams of the University of Hawaii. The scientists published their
findings in the December 1 edition of the Astrophysical Journal Letters.

This release is being issued jointly with NRAO.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation, operated under cooperative agreement by Associated
Universities, Inc. The Submillimeter Array is an 8-element interferometer
located atop Mauna Kea in Hawaii. It is a collaboration between the
Smithsonian Astrophysical Observatory and the Institute of Astronomy and
Astrophysics of the Academia Sinica of Taiwan.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.

[NOTE: An image supporting this release is available at
http://cfa-www.harvard.edu/press/200...33_images.html ]