Skies By Africa

Images of the Heavens By Eric Africa

NGC 7331 and the Deer Lick Group

Spiral galaxy NGC 7331 dominates this view of galaxies that is also known as the Deer Lick Group. The name of the group was reportedly given by Tomm Lorenzin, author of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing". This name was given in honor of the Deer Lick Gap in the mountains of North Carolina where he observed and had an especially fine view of this group of galaxies (source: Johannes Schedler).

NGC 7331 is a spiral galaxy about 40 million light-years away in the constellation Pegasus, and was discovered by William Herschel in 1784. Studies have indicated that in many respects, this galaxy has many physical similarities to our own Milky Way, and because of that it has been referred to as the Milky Way's twin. More recent discoveries about the Milky Way's structure have begun to raise doubts about this (source: Wikipedia).

One item of interest about NGC 7331 is that its central bulge rotates in the opposite direction of the rest of the galaxy's disk. This feature has been detected in other galaxies, so this peculiarity is not limited to this system. The cause of the counterrotation is still under study, but one possibility is a galactic merger in the distant past (recent discoveries have shown that galactic mergers are commonplace, and our own Milky Way is apparently on course for a merger with the Andromeda Galaxy in about 4 billion years).

The Deer Lick Group appears in to be a picturesque grouping of galaxies, but the three "smaller" galaxies in the image (NGC7336, 7335, 7337) are actually ten times more distant and just happen to lie in NGC 7331's line of sight (source: Robert Gendler).
Object: NGC 7331
Constellation: Pegasus
When Visible: September - December
Distance: 40 Million Light-years
Date: October - November 2015
Location: Rancho Hidalgo, New Mexico
Exposure Details:
Luminance: 32 x 10 minutes Binned 1 x 1
R: 10 x 10 minutes Binned 1 x 1
G: 10 x 10 minutes Binned 1 x 1
B: 10 x 10 minutes Binned 1 x 1

10 1/3 hours total exposure time
Equipment Used: 12.5" PlaneWave CDK on a Software Bisque Paramount ME mount. SBIG STL-6303 camera with 5-position filter wheel, AO-L Adaptive Optics Unit, Pyxis Rotator and Astrodon LRGB filters
Acquisition Software : MaximDL, CCDAutopilot, FocusMax, TheSky6
Processing Software: MaximDL, Adobe Photoshop CS5, IrFanView