To the left of centre is NGC 7331, a famous spiral galaxy, discovered by William Herschel in 1784. Reportedly, Tom Lorenzin (author of " The Amateur Astronomers' Field Guide to Deep Sky Observing") gave the name to the NGC 7331 group in honour of Deer Lick Gap in the mountains of North Carolina where he observed and once had an especially fine view of this group of galaxies.
NGC 7331, sometimes referred to as our galaxy's twin, is found in the constellation Pegasus at a distance of 49 million light-years. The other brighter galaxies around NGC 7331 are 10x more distant far in the background.
To the right of centre, Stephan's Quintet, also in Pegasus, is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. The group was discovered by Édouard Stephan in 1877 at Marseilles Observatory. The group is the most studied of all the compact galaxy groups. The brightest member of the visual grouping is NGC 7320 that is shown to have extensive H II regions where active star formation is occurring.
These galaxies are of interest because of their violent collisions. Four of the five galaxies in Stephan's Quintet form a physical association, Hickson Compact Group 92, and are involved in a cosmic dance that most likely will end with the galaxies merging. Radio observations in the early 1970s revealed a mysterious filament of emission which lies in inter-galactic space between the galaxies in the group. Two space telescopes have recently provided new insight into the nature of the strange filament, which is now believed to be a giant intergalactic shock-wave (similar to a sonic boom but traveling in intergalactic gas rather than air) caused by one galaxy (NGC 7318B) falling into the centre of the group at several millions of miles per hour.
There are many other smaller, more distant galaxies in this image if you look around.
Orion Optics UK AG16 Astrograph: SBIG 11000 CM: Titan Mount
38 x 4 minutes minutes (2hr 32 minutes total) single shot colour, processed with CCDStack, Photoshop, Pixinsight.
Data capture: 4th November 2013