Stephan's Quintet
Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered.
The group, visible in the constellation Pegasus, and was discovered by Édouard Stephan in 1877.
The group is the most studied of all the compact galaxy groups.
The brightest member of the visual grouping (and the only non-member of the true group) is NGC 7320 identified as red blobs, where active star formation is occurring.