Credit: NASA/JPL-Caltech/S. J. U. Higdon (Cornell University)

Dwarf Galaxies Swimming in Tidal Tails

This false-color infrared image from NASA's Spitzer Space Telescope shows little "dwarf galaxies" forming in the "tails" of two larger galaxies that are colliding together. The big galaxies are at the center of the picture, while the dwarfs can be seen as red dots in the red streamers, or tidal tails. The two blue dots above the big galaxies are stars in the foreground.

Galaxy mergers are common occurrences in the universe; for example, our own Milky Way galaxy will eventually smash into the nearby Andromeda galaxy. When two galaxies meet, they tend to rip each other apart, leaving a trail, called a tidal tail, of gas and dust in their wake. It is out of this galactic debris that new dwarf galaxies are born.

The new Spitzer picture demonstrates that these particular dwarfs are actively forming stars. The red color indicates the presence of dust produced in star-forming regions, including organic molecules called polycyclic aromatic hydrocarbons, or PAHs. PAHs are also found on Earth, in car exhaust and on burnt toast, among other places. Here, the PAHs are being heated up by the young stars, and, as a result, shine in infrared light.

This image was taken by the infrared array camera on Spitzer. It is a 4-color composite of infrared light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), and 8.0 microns (red). Starlight has been subtracted from the orange and red channels in order to enhance the dust, or PAH, features.

Image credit: NASA/JPL-Caltech/S. J. U. Higdon (Cornell University)

About the Object	Object Name: NGC 5291 Object Type: Interacting Galaxies Position (J2000): RA: 13h47m24.5s Dec: -30d24m25s Distance: 200 million light-years Constellation: Hydra
About the Data	Image Credit: NASA/JPL-Caltech/S. J. U. Higdon (Cornell University) Instrument: IRAC Wavelength: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange), 8.0 microns (red) Exposure Date: February 17, 2004 Exposure Time: 108 seconds per position Field of View: 8.5 x 7.1 arcmin Orientation: North is 140 deg clockwise from up Release Date: November 22, 2005
Observers	Sarah J. U. Higdon (Cornell University) James L. Higdon (Cornell University) Jason Marshall (Cornell University)

The Spitzer Space Telescope is a NASA mission managed by the Jet Propulsion Laboratory. This website is maintained by the Spitzer Science Center, located on the campus of the California Institute of Technology and part of NASA's Infrared Processing and Analysis Center.