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Martin Pugh

NGC 7331 & Stephan's Quintent


About this image.

Big, beautiful spiral galaxy NGC 7331, seen here on the right of the image, is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. The effect is further enhanced in this image by galaxies that lie beyond the gorgeous island universe. The background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen here through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is also known as the Deer Lick Group.

In contrast, Stephan's Quintet (at left) is about 300 million light-years away. Four galaxies of the group are actually locked in a cosmic dance of repeated close encounters. The odd man out is easy to spot, though. The four interacting galaxies (NGC 7319, 7318A, 7318B, and 7317) have an overall yellowish cast and tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides. But the larger bluish galaxy, NGC 7320, is much closer than the others. Just 40 million light-years distant, it isn't part of the interacting group. Stephan's Quintet lies within the boundaries of the high flying constellation Pegasus.

 (Text taken from NASA)
 

                               Full Size (11Mb)

 

Equipment

Telescope:                 Planwave 17" CDK f6.8
Mount:                      Paramount ME by Software Bisque
Instrument:               Apogee U16M, Astrodon Filters

Exposure:                  LRGB (6:2:2:2 hrs)
Capture Software:       CCDSOFT V5, CCDAutopilot
Processing:                Maxim DL/CCD, Photoshop CS, CCDStack, PixInsight

 

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