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Spitzer Spies Jet-Setting Stars
Rainbow-colored jets in the cosmic cloud BHR 71 point to a celestial smash occurring 600 light-years away from Earth. NASA's infrared Spitzer Space Telescope provides an exclusive peak at two "jet-setting stars" inside the cloud (right). These same stars are completely hidden from view in optical-light images (left).

The hot, young stars can be seen in the Spitzer image as yellow spots with dual rainbow-colored jets shooting out of them - one from the top and one from the bottom of each star. The colors in the jets represent infrared light: green reveals really hot hydrogen gas, orange shows warm gas, and the wisps of red represent the coolest gas. These infrared rainbows of color are exposed when shockwaves from the stars violently smash into surrounding gas and dust.

visible and infrared views of cosmic cloud BHR 71 Image right: Visible and infrared views of the cosmic cloud BHR 71. Image credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA
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"Spitzer offers a spectacular view of this region. In space, there are only a handful of places where we can see the chemical effects of stellar outflows on the surrounding cloud - and we see that in this Spitzer image," says Tyler Bourke of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.

The gas closest to the hot, young stars is hottest because the high-energy shockwaves collide into the dust and gas particles with incredible force. As the shockwaves travel away from these stars, resistance from the particles reduces their momentum. Collisions with material further away from the stars are thus not as intense, and gas there is not heated as much.

"Astronomers believe that all young stars at this stage of evolution produce jets. However, we don't always see these jets because they need a dense environment-with a lot of gas and dust -- to run into," says Bourke. "We also need infrared telescopes to measure heat created when the jets' shockwaves collide with gas molecules."

For years, stars inside BHR 71 have evaded the prying eyes of visible-light telescopes. In an optical image taken by the ground-based Very Large Telescope (left), BHR 71 is just a large black structure. A burst of yellow light toward the bottom of BHR 71 is the only indication that jet-setting starlets may lurk inside.

Before the Spitzer observations, astronomers suspected that this optical rupture was a hot young star's powerful jet breaking through the dense structure. This theory was confirmed when scientists combined the visible-light view of BHR 71 with Spitzer's infrared view. The visible-light jet overlaps exactly with the jet spouting out of the left star in the infrared image.

Bourke is the lead author of a paper on BHR 71 that is being prepared for publication in the Astrophysical Journal.

Written by Linda Vu, Spitzer Science Center
Media contact: Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.