Poster Version
This painterly portrait of a star-forming cloud, called NGC 346, is a
combination of multiwavelength light from NASA's Spitzer Space Telescope
(infrared), the European Southern Observatory's New Technology Telescope
(visible), and the European Space Agency's XMM-Newton space telescope
(X-ray).
The infrared observations highlight cold dust in red, visible data show
glowing gas in green, and X-rays show very warm gas in blue. Ordinary
stars appear as blue spots with white centers, while young stars
enshrouded in dust appear as red spots with white centers.
The colorful picture demonstrates that stars in this region are being
created by two different types of triggered star formation—one
involving wind, and the other, radiation. Triggered star formation occurs
when massive stars spur new, smaller stars into existence. The first
radiation-based mechanism is demonstrated near the center of the cloud.
There, radiation from the massive stars is eating away at the surrounding
dust cloud, creating shock waves that compress gas and dust into new
stars. This compressed material appears as an arc-shaped orange-red
filament, while the new stars within this filament are still blanketed
with dust and cannot be seen.
The second wind-based mechanism is at play higher up in the cloud. The
isolated, pinkish blob of stars at the upper left was triggered by winds
from a massive star located to the left of it. This massive star blew up
in a supernova explosion 50,000 years ago, but before it died, its winds
pushed gas and dust together into new stars. While this massive star
cannot be seen in the image, a bubble created when it exploded can be seen
near the large, white spot with a blue halo at the upper left (this white
spot is actually a collection of three stars).
NGC 346 is the brightest star-forming region in the Small Magellanic
Cloud, an irregular dwarf galaxy that orbits our Milky Way galaxy, 210,000
light-years away.
