Composite view of the Antennae Galaxies
Ssc2004 14a1

Credit: NASA/JPL-Caltech/Z. Wang (Harvard-Smithsonian CfA)

Observation • September 7th, 2004 • ssc2004-14a1


This infrared 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 is a false-color composite of infrared data from Spitzer and visible-light data from Kitt Peak National Observatory, Tucson, Ariz. Visible light from stars in the galaxies (blue and green) is shown together with infrared light from warm dust clouds heated by newborn stars (red). Wavelengths of .44 microns are represented in blue, .70 microns in green and 8.0 microns in red.

The two nuclei, or centers, of the merging galaxies show up as yellow-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.

About the Object

Antennae GalaxiesNGC 4038NGC 4039Arp 244
Galaxy > Type > Interacting
68,000,000 Light Years

Color Mapping

Band Wavelength Telescope
Optical 440 nm KPNO
Optical 700 nm KPNO
Infrared 8.0 ┬Ám Spitzer IRAC


Position (J2000)
RA =12h 1m 53.2s
Dec = -18° 52' 37.1"
Field of View
4.3 x 4.3 arcminutes
North is 4.5° right of vertical