The Dancing Galaxies of Stephan's Quintet

Image credit: NASA, ESA, Hubble; Processing: Daniel Nobre

Out of the numerous galaxies found in space, Stephan's Quintet shown above is the first cluster of galaxies ever to be discovered. First seen by Edouard Stephan in 1877 at the Marseille Observatory, it features four bright yellowish galaxies and one outlying, faintly bluish galaxy with a reddish core.

It's not visibly apparent but only four of these galaxies have constant interaction with one another causing them to be distorted by their gravitational forces.

The odd galaxy out is easy to spot in this recently reprocessed image by the Hubble Space Telescope -- the interacting galaxies, NGC 7319, 7318B, 7318A, and 7317 (left to right), have a more dominant yellowish cast. They also tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides.

NGC 7320, the bluish galaxy, is actually seven times closer to Earth than the others. The other four namely NGC 7317, 7318A, 7318B, and 7319 actively engage in a cosmic tango of sorts.

Upon closer inspection, scientists are saying that some of these galaxies may have started interacting with each other about a billion years ago. At some point, they also say that the cluster of four, collectively known as the Hickson Compact Group 92, would merge with one another.

Data and modeling indicate that NGC 7318B is a relatively new intruder. A recently-discovered halo of old red stars surrounding Stephan's Quintet indicate that at least some of these galaxies started tangling over a billion years. Stephan's Quintet is visible with a moderate sized-telescope toward the constellation of Winged Horse (Pegasus).

By Jeremiah