Galaxies and the Universe's Origins
Infrared emission from most galaxies comes primarily from three sources: stars, interstellar gas, and dust. With NASA's Spitzer Space Telescope astronomers can see which galaxies are furiously forming stars, locate the stellar nurseries, and pinpoint the cause of the stellar baby boom.
In looking at our own Milky Way galaxy, Spitzer has given astronomers valuable insights into the structure of our home galaxy by showing them where all the new stars are forming.
Spitzer also plays a significant role in helping astronomers understand Ultra Luminous Infrared Galaxies, or ULIRGs. These galaxies emit more than 90 percent of their light in the infrared, and are primarily found in the distant universe. With Spitzer's infrared eyes, astronomers can determine whether the source the ULIRG's infrared glow is from extreme star-formation or an active central supermassive black hole, or both.
Caption: Spitzer Space Telescope shows that the M51 spiral galaxy is rich in dust, and actively forming new stars, while its blue companion galaxy hosts an older stellar population.