Galaxy NGC 7331
About 40 million light-years distant in the constellation Pegasus, NGC 7331 is often touted as an analog to our own Milky Way Galaxy. Adam Block / Mount Lemmon SkyCenter / University of Arizona

Among the stars of Pegasus, the Winged Horse, are some of the fall sky’s best galaxy groups for backyard observers. Stephan’s Quintet is probably the best-known example of such a compact gathering, comprised of four gravitationally interacting galaxies and a prominent foreground galaxy, projected onto the more distant group by chance. But have you ever heard of the “Deer Lick Group”? No? Well, read on.

A trail blaze on the path to Stephan’s Quintet, NGC 7331 also anchors its own galaxy grouping. It is accompanied by several faint companions, including the smaller spiral galaxies NGC 7335 and NGC 7337, which are probably ten times farther away than NGC 7331. In the 1980s, author Tom Lorenzin bestowed the common name on this galaxy group to honor the Deer Lick Gap, which lies in the mountains of North Carolina. Apparently, Tom had a memorable view of these galaxies from there.

NGC 7335 and NGC 7337 are often erroneously referred to as satellites, but they are not associated with NGC 7331. The two companions glow at around magnitude +14, way too faint for most amateur scopes. NGC 7331, however, can even be spotted with larger binoculars.

Located about 4.5° northwest of Eta Pegasi, near the border of Lacerta, NGC 7331 was discovered in 1784 by William Herschel, and was one of the brightest galaxies overlooked by Messier in his catalog. It appears nearly edge on, tilted at an inclination of 77°. Its structure is remarkably similar to our own Milky Way Galaxy, with a comparable overall mass, spiral structure, distribution of stars, and central supermassive black hole.

Shining with the combined light of a 9th-magnitude star, NGC 7331 appears as a small fuzzy patch when viewed through binoculars. With an 8-inch telescope, a bright core appears and the beginnings of wispy arms. At 12-inches in aperture, spiral patterns emerge, and with good seeing conditions you will observe “patchiness” in the structure. Nebulous areas are revealed and the western half of the galaxy is deeply outlined with a dark dust lane.

Finder map – field width 15°, stars to magnitude +8.5.