Orbiting Observatory Detects Organic Chemistry In One Of The Most Luminous Galaxies Ever Found

http://www.news.cornell.edu/releases...Houck.deb.html

Orbiting observatory detects organic chemistry in one of the most
luminous galaxies ever found

FOR RELEASE: DEC. 18, 2003

Contact: David Brand
Office: 607-255-3651
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ITHACA, N.Y. -- An instrument aboard NASA's recently launched
orbiting infrared observatory has found evidence of organic molecules
in an enormously powerful galaxy some 3.25 billion light years from
the Earth. So powerful is the source, that it is equal to 10 trillion
times the luminosity of the sun, making it one of the brightest
galaxies ever detected.

The instrument on the newly named Spitzer Space Telescope (previously
called the Space Infrared Telescope Facility, or SIRTF) is the
infrared spectrograph, or IRS. James Houck, professor of astronomy at
Cornell University, heads the scientific team on the $39 million IRS
contract with the Jet Propulsion Laboratory, Pasadena, Calif., a
division of the California Institute of Technology, manager of the
mission for NASA.

Houck participated in a press conference at NASA headquarters in
Washington, D.C., today (Dec. 18) at which the first observations and
data from the half-billion-dollar observatory, launched Aug. 25, were
released. Among the most spectacular details released were dazzling
images taken with the space telescope's infrared-array camera and
with its multiband-imaging photometer. The images include a glowing
stellar nursery; a swirling, dusty galaxy; a disc of planet-forming
debris; and organic material in the distant universe.

The IRS, one of three instruments carried by the space telescope, is
the most sensitive infrared spectrograph ever to go into space. In
less than 15 minutes it produced a spectrum of the distant galaxy
IRAS 00183, first observed by the infrared astronomical satellite
(IRAS) in 1983. The spectrum "gives evidence for organic chemistry in
a distant galaxy shortly after the formation of the Earth," says
Houck. (While the Spitzer observatory's cameras take infrared
snapshots of distant galaxies and dust clouds, and objects too cool
to emit visible light, the IRS determines their precise infrared
colors. Astronomers are then able to read the peaks and valleys in
the spectrum, called emission and absorption lines, to determine the
chemical mix of the object being observed.)

In an optical image, the IRAS galaxy appears as no more than a faint
smudge. But the IRS spectrum -- the first detailed look at the galaxy
-- shows a broad silicate feature. The dominant absorber of visible
energy is tiny silicate dust particles. The silicate dust is so
opaque that only a small percentage of the visible light escapes the
galaxy, says Houck.

"We are seeing the merger of two galaxies. This produces one of two
effects: Either what we are seeing is a brief flash of incredibly
strong star formation, or one or both of the galaxies contained a
black hole before colliding. The massive black holes are releasing
the energy by swallowing stars and gas," says Houck. In both cases,
he says, the collision would compress gas that would trigger the star
formation or the release of energy from the black hole, a process
called "feeding the monster."

Both scenarios have problems, Houck concedes. "One is, how do you get
enough gas close enough to a black hole to make all this happen? And
how do you get stars to form so quickly all at the same time?"

Houck's IRS team also released a spectrum of HH46IR, a "dusty, dirty
cloud" in our galaxy, the Milky Way, that visible light is unable to
penetrate. The spectrum shows the cloud to be a region of star
formation containing organic materials, including methyl alcohol,
carbon dioxide ice and carbon monoxide gas and ice.

Houck also notes that the IRS is "working well" and is likely to be
"a workhorse for years to come." During November, he relates, the
instrument was subject to a massive proton "storm" in space, with 1.6
billion atomic particles (mostly protons) bombarding a square
centimeter of the instrument in just two days. "It was a staggering
event," he says.



Related World Wide Web sites: The following sites provide
additional information on this news release. Some might not be part
of the Cornell University community, and Cornell has no control over
their content or availability.

o Spitzer Space Telescope/JPL: http://sirtf.caltech.edu/

o Cornell News Service reports on Spitzer/IRS:

http://www.news.cornell.edu/releases/SIRTF/

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