August 22, 2008—Several generations of stars "pose" for a family portrait amid curtains of clouds in the star-forming region called W5, about 6,500 light-years away.

The composite image was released today to mark the upcoming five-year anniversary of the Spitzer Space Telescope, which lifted off from Cape Canaveral Air Force Station in Florida on August 25, 2003.

Since its launch, Spitzer's infrared images have been helping astronomers peer through gases and dust that can block visible light, revealing distant cosmic objects in high detail.

The latest image of W5 uncovered a stellar family tree that offers scientists new evidence for the theory of triggered star formation. This is when powerful winds from massive stars carve out cavities inside nebulae, compressing gases along the rims of the cavities and spawning new stars.

Using Spitzer data, a team led by Xavier Koenig at the Harvard-Smithsonian Center for Astrophysics found that cavities in W5 do contain ladder-like progressions of stellar generations, with older stars (blue dots) inside the hollows and younger stars (pink and white dots) around the rims.

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