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Old 06-08-2013, 08:25 PM
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madbadgalaxyman (Robert)
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Join Date: Mar 2011
Location: Brisbane
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Hi Mike,

as usual, the depth and resolution of your image is very good, which is why I am interested in your image, insofar as investigating what is going on in NGC 6771......this galaxy is - in its way - much more interesting and unusual than the two mildly distorted face-on spirals!

This edge-on S0 galaxy has an unusual bulge;
this is a "giant boxy/x-shaped bulge", and some modelling indicates that these giant boxy or x-shaped bulges may be the product of galaxy mergers. (some people call them "peanut shaped bulges"). There are plenty of these bulges in some clusters of galaxies, but their origin and nature is not fully understood!!

To save a lot of explanation, I discuss the various types of bulges in the "Observation Reports" forum thread called "AGCS 805 observed".....

http://www.iceinspace.com.au/forum/s...=NGC+6771+boxy

In this thread, you can find pictures and isophotes of several galaxies which have very big and very rectangular bulges that sometimes simultaneously look X-shaped.
NGC 6771 is an excellent example of this morphology, a type of structure that is relatively common in some high-galaxy-density environments like galaxy clusters.

It might be interesting to see what your high-contrast image of NGC 6771 looks like, enlarged significantly , and at various levels of contrast.

The complexity of structure in these giant boxy bulges is hinted at in this image of N6771 from star shadows observatory (reproduced at two different levels of contrast):

Click image for larger version

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Click image for larger version

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Best regards,
Robert
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