Infrared Legacy


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Hidden behind a curtain of dusty darkness lurks one of the most violent pockets of star birth in our galaxy. Called DR21, this stellar nursery is so draped in cosmic dust that it appears invisible to the human eye.

By seeing in the infrared, NASA's Spitzer Space Telescope has pulled this veil aside, revealing a fireworks-like display of massive stars. The biggest of these stars is estimated to be 100,000 times as bright as our own Sun.

Located about 10,000 light-years away in the Cygnus constellation of our Milky Way galaxy, DR21 is a turbulent nest of giant newborn stars. The region is buried in so much space dust that no visible light escapes it. Previous images taken with radio and near-infrared bands of light reveal a powerful jet emanating from a huge, nebulous cloud. But these views are just the tip of the iceberg.

Spitzer's highly sensitive infrared detectors were able to see past the obscuring dust to the stars behind. This colorful image is a large-scale composite mosaic assembled from data collected at a variety of different wavelengths. Views at visible wavelengths appear blue, near-infrared light is depicted as green, and mid-infrared data from the InfraRed Array Camera (IRAC) aboard NASA's Spitzer Space Telescope is portrayed as red. The result is a contrast between structures seen in visible light (blue) and those observed in the infrared (yellow and red). A quick glance shows that most of the action in this image is revealed to the unique eyes of Spitzer. The image covers an area about two times that of a full moon.

The red filaments stretching across the image (from Spitzer data) show the presence of polycyclic aromatic hydrocarbons. These organic molecules, which are made up of carbon and hydrogen, are excited by surrounding interstellar radiation and become luminescent at wavelengths near 8 microns. The complex pattern of filaments is caused by an intricate combination of radiation pressure, gravity, and magnetic fields. The result is a tapestry in which winds, outflows, and turbulence move and shape the interstellar medium.

Image credits: NASA/JPL-Caltech/A. Marston (ESTEC/ESA)