Antennae Galaxies
A name for the two colliding galaxies NGC 4038 and NGC 4039 about 68 million ly distant. The name derives from the two long, curved streams of stars and dust formed in the initial collision, that resemble the antennae of an insect. The tidal streams are approximately 100 000 light years across.
General information
The Antennae Galaxies are a part of the NGC 4038 group with five others. The nuclei of the two galaxies are joining to become one supergalaxy. Most galaxies probably undergo at least one significant collision in their lifetimes; This is likely the future of our Milky Way when it collides with Andromeda.
Timeline
Antennae's past
About 1.2 billion years ago, the Antennae were two separate galaxies. NGC 4038 was a spiral galaxy and NGC 4039 was a barred spiral galaxy, even though they are still spiral and barred spiral. It may look like NGC 4038 is larger then NGC 4039, but before they collieded, NGC 4039 was larger than NGC 4038. 900 million years ago, the Antennae started to get close to each other, looking similar to NGC 2207 and IC 2163. 600 million years ago, the Antennae had already gone through each other, looking like the Mice Galaxies. 300 million years ago, the Antennae's stars began to be flung out of both galaxies. Today the two streamers of ejected stars extend far beyond the original galaxies, making the antennae shape.
Antennae's future
Within 400 million years, the Antennae's nuclei will colide and become a single core with stars, gas, and dust around it. With in a billion years the galaxy shall look like a normal galaxy, the 'Antenna Galaxy'. It's not 100% sure whether it'll be a spiral or a barred spiral galaxy. The brand new galaxy will go on for billions of years, maybe with more collisions in its future.