[Spitzer-news] Galaxy on Fire! NASA's Spitzer Reveals Stellar Smoke

spitzer-news at lists.ipac.caltech.edu spitzer-news at lists.ipac.caltech.edu
Thu Mar 16 10:12:57 PST 2006


Where there's smoke, there's fire - even in outer space. A new infrared
image from NASA's Spitzer Space Telescope shows a burning hot galaxy
whose fiery stars appear to be blowing out giant billows of smoky dust.

The galaxy, called Messier 82, or the "Cigar galaxy," was previously
known to host a hotbed of young, massive stars. The new Spitzer image
reveals, for the first time, the "smoke" surrounding those stellar

"We've never seen anything like this," said Dr. Charles Engelbracht of
the University of Arizona, Tucson. "This unusual galaxy has ejected an
enormous amount of dust to cover itself with a cloud brighter than any
we've seen around other galaxies."

The false-colored view, online at http://www.spitzer.caltech.edu/Media ,
shows  Messier 82, an irregular-shaped galaxy positioned on its side, as
a diffuse bar of blue light. Fanning out from its top and bottom like
the wings of a butterfly are huge red clouds of dust believed to contain
a compound similar to car exhaust. 

The smelly material, called polycyclic aromatic hydrocarbon, can be
found on Earth in tailpipes, barbecue pits and other places where
combustion reactions have occurred.  In galaxies, the stuff is created
by stars, whose winds and radiation blow the material out into space. 

"Usually you see smoke before a fire, but we knew about the fire in this
galaxy before Spitzer's infrared eyes saw the smoke," said Dr. David
Leisawitz, Spitzer program scientist at NASA Headquarters in Washington. 

These hazy clouds are some of the biggest ever seen around a galaxy.
They stretch out 20,000 light-years away from the galactic plane in both
directions, far beyond where stars are found.

Previous observations of Messier 82 had revealed two cone-shaped clouds
of very hot gas projecting outward below and above the center of galaxy.
Spitzer's sensitive infrared vision allowed astronomers to see the
galaxy's dust.

"Spitzer showed us a dust halo all around this galaxy," said
Engelbracht.  "We still don't understand why the dust is all over the
place and not cone-shaped." 

Cone-shaped clouds of dust around this galaxy would have indicated that
its central, massive stars had sprayed the dust into space. Instead,
Engelbracht and his team believe stars throughout the galaxy are sending
off the "smoke signals." 

Messier 82 is located about 12 million light-years away in the Ursa
Major constellation.  It is undergoing a renaissance of star birth in
its middle age, with the most intense bursts of star formation taking
place at its core. The galaxy's interaction with its neighbor, a larger
galaxy called Messier 81, is the cause of all the stellar ruckus. Our
own Milky Way galaxy is a less hectic place, with dust confined to the
galactic plane.

The findings will appear in an upcoming issue of the Astrophysical
Journal. Other authors who contributed significantly to this work are
Praveen Kundurthy and Dr. Karl Gordon, both of the University of
Arizona. The image was taken as a part of the Spitzer Infrared Nearby
Galaxy Survey, which is led by Dr. Robert Kennicutt, also of the
University of Arizona.

The Jet Propulsion Laboratory manages the Spitzer Space Telescope
mission for NASA's Science Mission Directorate, Washington. Science
operations are conducted at the Spitzer Science Center at Caltech. JPL
is a division of Caltech. 

For more information about Spitzer, visit
http://www.spitzer.caltech.edu/spitzer . For more information about NASA
and agency programs on the Web, visit http://www.nasa.gov/home/ .

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