Credit: NASA/JPL-Caltech/Univ. of Wisc.
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, can be found online in the Spitzer Image Gallery. 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 million 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.
Whitney Clavin 818-354-4673
Jet Propulsion Laboratory
whitney.clavin@jpl.nasa.gov
About the Image:
(1) NASA's Spitzer Space Telescope has captured a new, infrared view of the choppy star-making cloud called M17, also known as Omega Nebula or the Swan nebula.
The cloud, located about 6,000 light-years away in the constellation Sagittarius, is dominated by a central group of massive stars -- the most massive stars in the region (see yellow circle). These central stars give off intense flows of expanding gas, which rush like rivers against dense piles of material, carving out the deep pocket at center of the picture. Winds from the region's other massive stars push back against these oncoming rivers, creating bow shocks like those that pile up in front of speeding boats.
Three of these bow shocks are labeled in the magnified inset. They are composed of compressed gas in addition to dust that glows at infrared wavelengths Spitzer can see. The smiley-shaped bow shocks curve away from the stellar winds of the central massive stars.
This picture was taken with Spitzer's infrared array camera. It is a four-color composite, in which light with a wavelength of 3.6 microns is blue; 4.5-micron light is green; 5.8-micron light is orange; and 8-micron light is red. Dust is red, hot gas is green and white is where gas and dust intermingle. Foreground and background stars appear scattered through the image.
About the Object:
Object name: Omega Nebula, Swan Nebula, M 17, NGC 6618
Object type: Star Formation
Position (J2000): RA: 18h 20m 26.00s Dec: -16° 10' 0.00"
Distance: 5,200 Light Years
Constellation: Sagittarius
Instrument: IRAC
