This false-color image from NASA's Spitzer Space Telescope reveals hidden
populations of newborn stars at the heart of the colliding "Antennae"
galaxies. These two galaxies, known individually as NGC 4038 and 4039,
are located around 68 million light-years away and have been merging
together for about the last 800 million years. The latest Spitzer
observations provide a snapshot of the tremendous burst of star formation
triggered in the process of this collision, particularly at the site
where the two galaxies overlap.
The image was taken by Spitzer's infrared array camera and is a
combination of infrared light ranging from 3.6 microns (shown in blue) to
8.0 microns (shown in red). The dust emission (red) is by far the
strongest feature in this image. Starlight was systematically subtracted
from the longer wavelength data (red) to enhance dust features.
The two nuclei, or centers, of the merging galaxies show up as white
areas, one above the other. The brightest clouds of forming stars lie in
the overlap region between and left of the nuclei.
Throughout the sky, astronomers have identified many of these so-called
"interacting" galaxies, whose spiral discs have been stretched and
distorted by their mutual gravity as they pass close to one another.
The distances involved are so large that the interactions evolve on
timescales comparable to geologic changes on Earth. Observations of such
galaxies, combined with computer models of these collisions, show that
the galaxies often become forever bound to one another, eventually
merging into a single, spheroidal-shaped galaxy.
Wavelengths of 3.6 microns are represented in blue, 4.5 microns in green
and 5.8-8.0 microns in red. This image was taken on Dec. 24, 2003.
