Splashy Portrait Helps Explain How Stars Form
Different wavelengths of light swirl together like watercolors
in a new, ethereal portrait of a bright, star-forming region.
The multi-wavelength picture combines infrared, visible and X-ray
light from NASA's Spitzer Space Telescope, the European Southern
Observatory's New Technology Telescope, and the European Space
Agency's XMM-Newton orbiting X-Ray telescope, respectively.
The colorful image offers a fresh look at the history of the star-studded
region, called NGC 346, revealing new information about how stars form
in the universe. NGC 346 is the brightest star-forming region in the
Small Magellanic Cloud, a so-called irregular dwarf galaxy that orbits
our Milky Way galaxy, 210,000 light-years away.
"NGC 346 is an astronomical zoo," said Dimitrios Gouliermis of the Max
Planck Institute for Astronomy in Germany, lead author of a new paper
describing the observations in an upcoming issue of the Astrophysical
Journal. "When we combined data at various wavelengths, we were able to
tease apart what's going on in different parts of the cloud."
The new picture is available online at:
Small stars are scattered throughout the NGC 346 region, while massive
stars populate its center. The massive stars and most of the small stars
formed at the same time out of one dense cloud, while other small stars
were created later through a process called triggered star formation.
Intense radiation from massive stars ate away at the surrounding dusty
cloud, triggering gas to expand and create shock waves that compressed
nearby cold dust and gas into new stars. The red-orange filaments
surrounding the center of the image show where this process has occurred.
But a set of even younger small stars in the region, seen as a pinkish
blob at the top of the image, couldn't be explained by this mechanism.
Scientists were scratching their heads over what caused this seemingly
isolated group of stars to form.
By combining multi-wavelength data of NGC 346, Gouliermis says he and
his team were able to pinpoint the trigger as a very massive star that
blasted apart in a supernova explosion about 50,000 years ago. According
to the astronomers, this very massive star spurred the isolated young stars
into existence before it died, but through a different type of triggered star
formation than that which occurred near the center of the region. Fierce
winds from the massive star, and not radiation, pushed dust and gas together,
compressing it into new stars.
The finding demonstrates that both wind- and radiation-induced triggered
star formation are at play in the same cloud. According to Gouliermis, "The
result shows us that star formation is a far more complicated process than
we used to believe, comprising different competitive or collaborative mechanisms."
The new image also reveals a bubble, seen as a blue halo to the left, caused
by the supernova explosion that happened 50,000 years ago. Further analysis
shows that this bubble is located within a large expanding gaseous shell,
possibly powered by the explosion and the winds of other bright stars in its vicinity.
Infrared light (red) shows cold dust; visible light (green) denotes glowing gas;
and X-rays (blue) represent very warm gas. Ordinary stars appear as blue spots
with white centers, while young stars enshrouded in dust appear as red spots
with white centers.
Other authors of this paper include Thomas Henning and Wolfgang Brandner of
the Max Planck Institute for Astronomy, and You-Hua Chu and Robert Gruendl of
the University of Illinois at Urbana-Champaign.
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.
More information about Spitzer is at http://www.spitzer.caltech.edu/spitzer
Media contact: Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.