NGC 7331, the Deer Lick Group and Stephan’s Quintet

NGC 7331 is an unbarred spiral galaxy about 40 million light-years away in the constellation Pegasus. NGC 7331 is the brightest member of the NGC 7331 Group of galaxies, also known as the Deer Lick Group. The other members of the group are the lenticular or unbarred spirals NGC 7335 and 7336, the barred spiral galaxy NGC 7337 and the elliptical galaxy NGC 7340. These galaxies lie at distances of approximately 332, 365, 348 and 294 million light years, respectively. In both visible light and infrared photos of NGC 7331, the core of the galaxy appears to be slightly off-center, with one side of the disk appearing to extend further away from the core than the opposite side.

In the lower left corner is Stephan’s Quintet, a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. These four galaxies in Stephan’s Quintet form a physical association, Hickson Compact Group 92, and will likely merge with each other. The fifth galaxy, NGC 7320, with a distinctive bluish color and spiral morphology has a redshift of only 0.002622 z. This places it at a mere 46.6 million light-years away or less than an eighth of the average distance of 380 million light-years for the other four galaxies according to the distance/acceleration interpretation of redshifts.

Stephan’s Quintet (Left) and NGC 7331 (Right)

Telescope: 16″ f3.75 Dream Scope
Camera: FLI ML16803
Mount: ASA DDM85
Exposure: 9.5 hours (54x300s L + 3x20x300s RGB)
Date: July – August 2019
Location: Southern Alps, France

 

Larger FOV with correct orientation

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