Violent Galactic Collision: Stephan’s Quintet


Stephan's Quintet

Violent Galactic Collision

What happens when galaxies get too close to one another?  Why a galactic collision of course!  Stephan’s Quintet happens to be a pretty violent one.

Stephan’s Quintet is a cluster of five galaxies located 280 million light years away from Earth in the constellation Pegasus.  It is known as a compact galaxy group and this one happens to be one of the most studied compact galaxy groups in the cosmos. 

If you take a close look at the picture above, you will notice that three of the galaxies are distorted.  You would expect to see symmetry in the spiral arms and dust lanes of these galaxies, but here, they are warped and stretched out.  It almost looks like a part of one galaxy is being flung off into inter-galactic space.  This distortion is caused by the gravitational tidal forces of the independent galaxies interacting with one another.  The result is new star forming regions – which can be seen as the bright blue stars within pink cloud regions of glowing hydrogen.

Stephan’s Quintet is also known as the Hickson Compact Group 92.  The galaxies within the group are NCG 7319 which is at the top right.  Going in a clock-wise direction, the next two galaxies are NGC 7318A and NGC 7318B.    NGC 7317 is at bottom left and finally, NGC 7320 is at the upper left.

Stephan’s Quintet was the first compact group ever discovered.  Edouard M. Stephan found it in 1877. 

Image Credit:  NASA, ESA and the Hubble SM4 ERO Team



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