The Antennae Galaxies

This is one of my favourite galaxies, in fact, it is a collision of two galaxies, the NGC 4038 and 4039. Its shape gives the name away. It’s in the Corvus constellation in the Southern Hemisphere, encompassed by the Virgo and Hydra constellations. It is a favourite because it shows 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. Visible light from newborn stars in the galaxies (blue and green) is shown together with infrared light from warm dust clouds heated by more mature stars (red).

This image (the group of 3 pics below) from NASA’s Spitzer Space Telescope reveals hidden populations of newborn stars at the heart of the colliding “Antennae” galaxies located around 68 million light-years away and have been merging together for about the last 800 million years. The main image is a composite of infrared data from Spitzer and visible-light data from Kitt Peak National Observatory, Tucson, Ariz. 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.

The upper right panel shows the Spitzer image by itself. This picture was taken by the 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 lower right panel shows the true-color, visible-light image by itself. Here, we find a strikingly different view, with the bright star-forming features seen in the Spitzer image buried within dark clouds of dust. The Spitzer image was taken on Dec. 24, 2003.