Galaxy Exposes Its Dusty Inner Workings in New Spitzer Image


http://www.jpl.nasa.gov/news/news.cfm?release=2010-003

Galaxy Exposes Its Dusty Inner Workings in New Spitzer Image
Jet Propulsion Laboratory
January 05, 2010

NASA's Spitzer Space Telescope has captured an action-packed picture of
the nearby Small Magellanic Cloud, a small galaxy that looks like a
wispy cloud when seen from Earth.

From Spitzer's perch up in space, the galaxy's clouds of dust and stars
come into clear view. The telescope's infrared vision reveals choppy
piles of recycled stardust -- dust that is being soaked up by new star
systems and blown out by old ones.

To some people, the new view might resemble a sea creature, or even a
Rorschach inkblot test. But to astronomers, it offers a unique
opportunity to study the whole life cycle of stars close-up. The image
is available online at http://www.nasa.gov/AAS and
http://www.jpl.nasa.gov/aas .

"It's quite the treasure trove," said Karl Gordon, the principal
investigator of the latest Spitzer observations at the Space Telescope
Science Institute in Baltimore, Md. "Because this galaxy is so close and
relatively large, we can study all the various stages and facets of how
stars form in one environment."

The Small Magellanic Cloud, and its larger sister galaxy, the Large
Magellanic Cloud, are named after the seafaring explorer Ferdinand
Magellan, who documented them while circling the globe nearly 500 years
ago. From Earth's southern hemisphere, they can appear as wispy clouds.
The Small Magellanic Cloud is the farther of the pair, at 200,000
light-years away.

Recent research has shown that the galaxies may not, as previously
suspected, orbit around the Milky Way. Instead, they are thought to be
merely sailing by, destined to go their own way. Astronomers say the two
galaxies, which are both less evolved than a galaxy like ours, were
triggered to create bursts of new stars by gravitational interactions
with the Milky Way and with each other. In fact, the Large Magellanic
Cloud may eventually consume its smaller companion.

Gordon and his team are interested in the Small Magellanic Cloud not
only because it is so close and compact, but also because it is very
similar to young galaxies thought to populate the universe billions of
years ago. The Small Magellanic Cloud has only one-fifth the amount of
heavier elements, such as carbon, contained in the Milky Way, which
means that its stars haven't been around long enough to pump large
amounts of these elements back into their environment. Such elements
were necessary for life to form in our solar system.

Studies of the Small Magellanic Cloud therefore offer a glimpse into the
different types of environments in which stars form.

The new Spitzer observations were presented today at the 215th meeting
of the American Astronomical Society in Washington. They reveal the
galaxy's youngest stars embedded in thick dust, in addition to the older
stars, which spit the dust out. Taken together with visible-light
observations, these Spitzer data help provide a census of the whole
stellar population.

"With Spitzer, we are pinpointing how to best calculate the numbers of
new stars that are forming right now," said Gordon. "Observations in the
infrared give us a view into the birthplace of stars, unveiling the
dust-enshrouded locations where stars have just formed."

Infrared light is color-coded in the new picture, so that blue shows
older stars, green shows organic dust and red highlights dust-enshrouded
star formation. Light encoded in blue has a wavelength of 3.6 microns;
green is 8.0 microns; and red is 24 microns. This image was taken before
Spitzer ran out of its liquid coolant in May 2009 and began its "warm"
mission.

Other collaborators include: M. Meixner, M, Sewilo and B. Shiao of the
Space Telescope Science Institute; M. Meade, B. Babler, S. Bracker of
the University of Wisconsin at Madison; C. Engelbracht, M. Block, K.
Misselt of the University of Arizona, Tucson; R. Indebetouw of the
University of Virginia, Charlottesville; and J. Hora and T. Robitaille
of the Harvard Smithsonian Center for Astrophysics, Cambridge, Mass.

The image includes Spitzer observations taken previously by a team led
by Alberto Bolatto of the University of Maryland, College Park.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer
Space Telescope mission for NASA's Science Mission Directorate,
Washington. Science operations are conducted at the Spitzer Science
Center at the California Institute of Technology in Pasadena. Caltech
manages JPL for NASA.

For more information about Spitzer, visit
http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
whitney.clavin@xxxxxxxxxxxx

2010-003

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