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NGC 7331 (also known as Caldwell 30) is a spiral galaxy about 40 million light-years (12 Mpc) away in the constellation Pegasus. It was discovered by William Herschel in 1784. NGC 7331 is the brightest member of the NGC 7331 Group of galaxies, which is the group just below NGC 7331.
Another prominent group of galaxies in the image, to the upper right in the image, is 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 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. Also of interest, NGC 7320 indicates a small redshift (790 km/s) while the other four exhibit large redshifts (near 6600 km/s). Since galactic redshift is proportional to distance, NGC 7320 is only a foreground projection and is ~39 million ly from Earth versus the 210-340 million ly of the other galaxies in the group.
There are also other faint galaxies in the image if you look hard enough.
Image:
6 x 300 sec = 30 minutes total exposure at ISO 1600.
Image taken on August 26, 2011 at the Louisville Astronomical Society James Baker Center for Astronomy, in Curby, Indiana.
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