What happens when there is a gigantic collision of two immense intergalactic vehicles called galaxies each containing over 100 billion individual components called stars? Well, surprisingly, it is very unlikely that any of the stars will collide due to the vast distances between them and the extreme emptiness of space. However, the interacting gravity stirring up the interstellar medium results in bursts of star formation like no other!

The Antennae Galaxies, or Rat Tail Galaxies, are two interacting galaxies, likely in the phase of joining to become a single larger galaxy! They are located in the direction of the constellation Corvus, “the crow” in Latin. These two galaxies are designated NGC 4038 and 4039 in the New Generation Catalog of Nebula and Clusters of Stars, as well as C60 and C61 in the Caldwell Catalogue of star clusters, nebulae, and galaxies. This catalog was created by Patrick Moore as a complement to the more famous Messier catalogue. Note Moore used his other surname “Caldwell” to designate objects C1 through C109, since M was already taken for the Messier objects.

The two nuclei of NGC 4038 and 4039 will eventually merge in about 400 million years to form a single much more massive galaxy and with a combined supermassive black hole at its center.  Named the Antennae Galaxies due to their long tails of stars, gas, and dust, these galaxies are currently in an extreme starburst phase where the collision of gas and dust cause significant and rapid amount of star formation. This galaxy pair is also a relatively strong source of X-rays which also shows large amounts of neon, magnesium, and silicon.

These galaxies are home to some of the youngest globular clusters observed. Most globulars are over 10 billion years old, but these are just 1-2 billion, likely due to the compression of large molecular clouds around and withing the galaxies, thereby causing massive numbers of stars to form in relatively short order.

The two galaxies started to merge about 1.2 billion years ago and passed through each other 600 million years ago. This type of merger will likely happen in about a billion years from now between our own Milky Way galaxy and its neighbor, the Andromeda Galaxy.

The upper galaxy in this image, NGC 4038, has also been the home to five supernovae in the past century. Within about 400 million years, the colliding cores of these galaxies will merge into one, forming a single massive elliptical galaxy. Note, for comparison how faint these galaxies are, the bright star at the center top of this image is 8.7 magnitude star which is 12 time fainter than the faintest star visible by humans in a very dark site. Yet this single faint star is 5 times brighter than the combined light output of the entire galaxy as visible from earth.

The first image below demonstrates the improved processing technique using PixInsight software. Hovering a mouse over the image* demonstrates the before and after affect. The second image below is a zoomed in view of the cores of both galaxies showing the extreme starburst formation as well as disturbed star, gas, and dust of both galaxies.

The stats for NGC 4038 are RA: 12h 01m 53.1s, Dec: -18° 52' 02", Mag: 10.9 (P), Size: 3.7'x1.7', Class: SB(s)m pec and Position Angle 94. The stats for NGC 4039 are RA: 12h 01m 52.9s, Dec: -18° 53' 29", Mag: 11.1 (P), Size: 4.0'x2.2', Class: SA(s)m pec and Position Angle 62.

*Using a mouse, hover over the image above for annotations. This hover feature may be unavailable on smart phones.