Rivers of Gas Flow Around Stars in New Space Image

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Whitney Clavin 818-354-4673
Jet Propulsion Laboratory
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IMAGE ADVISORY: 2008-228 Dec. 8, 2008

Rivers of Gas Flow Around Stars in New Space Image

A new image from NASA's Spitzer Space Telescope shows a turbulent star-forming
region, where rivers of gas and stellar winds are eroding thickets of dusty material.

The picture provides some of the best examples yet of the ripples of gas, or bow shocks,
that can form around stars in choppy cosmic waters.

"The stars are like rocks in a rushing river," said Matt Povich of the University of
Wisconsin, Madison. "Powerful winds from the most massive stars at the center of the
cloud produce a large flow of expanding gas. This gas then piles up with dust in front of
winds from other massive stars that are pushing back against the flow." Povich is lead
author of a paper describing the new findings in the Dec. 10 issue of the Astrophysical
Journal.

Spitzer's new infrared view of the stormy region, called M17, or the Swan nebula, is
online at http://www.nasa.gov/mission_pages/spitzer/multimedia/20081208.html .
The Swan is located about 6,000 light-years away in the constellation Sagittarius.

Dominating the center of the Swan is a group of massive stars, some exceeding 40 times
the mass of our sun. These central stars are 100,000 to one million times as bright as the
sun, and roar with radiation and fierce winds made of charged particles that speed along
at up to 7.2 kilometers per hour (4.5 million miles per hour). Both the wind and radiation
carve out a deep cavity at the center of the picture -- an ongoing process thought to
trigger the birth of new stars.

The growth of this cavity pushes gas up against winds from other massive stars, causing
"smiley-faced" bow shocks -- three of which can be seen in the new picture. The
direction of the bow shocks tells researchers exactly which way the "wind is blowing."

"The bow shocks are like interstellar weather vanes, indicating the direction of the stellar
winds in the nebula," said Povich.

Povich and his colleagues also used Spitzer to take an infrared picture of a star-forming
region called RCW 49. Both photographs are described in the same Astrophysical Journal
paper, and both provide the first examples of multiple bow shocks around the massive
stars of star-forming regions.

Spitzer was able to spot the bow shocks because its infrared eyes can pierce intervening
dust, and because it can photograph large swaths of sky quickly.

Ultimately, the new observations will help researchers understand how solar systems like
our own are able to form and persist in the rough, celestial seas of space.

"The gas being lit up in these star-forming regions looks very wispy and fragile, but looks
can be deceiving," said co-author Robert Benjamin of the University of Wisconsin,
Whitewater. "These bow shocks serve as a reminder that stars aren't born in quiet
nurseries but in violent regions buffeted by winds more powerful than anything we see on
Earth."

Other authors include Barbara A. Whitney of the Space Science Institute, Boulder, Colo.;
Brian L. Babler, Marilyn R. Meade and Ed Churchwell of the University of Wisconsin,
Madison; and Remy Indebetouw of the University of Virginia, Charlottesville.

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, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array
camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The
instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center
for Astrophysics.

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

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