Stephan's Quintet of Galaxies

Click on image for larger version.

As the name implies, there are 5 major galaxies here- but the casual observer will note a sixth galaxy on the left side of the image. This group of galaxies (as well as a few others) is often quoted as being an example of "discordant redshift." The idea is that we live in an expanding universe, and galaxies that are far from us appear to recede at some rate accordingly. If galaxies are at the same distance from us, their recessional velocities should be the same. However, in this example 4 out of 5 galaxies have the same speed- the large spiral in the bottom right (4 O'clock) of the group has a recessional speed of half the rest! So, perhaps this galaxy is in the foreground and we are witnessing some chance alignment. Or, can you see evidence of gravitional interaction between this galaxy and the 4 others? (which would place them at the same distance). To-date there isn't much agreement- but for this particular set of galaxies the consensus is that this errant member is not related. There are many other examples that have yet to be explained. Visit another NOAO image for a similar explanation.

Equipment

20in RC Optical Systems telescope Operating at f/8.4
Paramount ME Robotic Telescope Mount
SBIG ST10XME CCD camera with color filter wheel

L R G B color production was used to create this image.

Luminance = 150 minutes binned 1x1
Red = 20 minutes binned 2x2
Green = 20 minutes binned 2x2
Blue = 20 minutes binned 2x2

Luminance data taken through thin clouds (on one night) and smoke (on the next).

One iteration of CCDsharp was applied to this image.

Digital Development (DDP) via Maxim/DL was also used in order to display the the very dim and very bright details of the image simultaneously.

Minimum credit line: Adam Block/NOAO/AURA/NSF

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Updated: 7/06/2003