G'day there Ray,
Your shot is nice and deep, and the angular resolution looks good. In fact, it has dragged me away from my studies of single-celled animals and lobe-finned fishes!
Yeah, the giant spiral is very pretty and somewhat distorted, but what really interests me is the unusual "layered" (onionlike) structure of the big elliptical NGC 6876, with various position angles and ellipticities of its outline that are dependent on the surface brightness to which its image is displayed. This big elliptical galaxy also has a remarkably extended extremely-extremely-faint outermost halo, which I seem to pick up when I try to stretch your .jpg
Here is the outer halo, from one of David Malin's "co-added UK Schmidt plates" images : :
Attachment 169098
As you can see, the true size of NGC 6876 is absolutely colossal!
The isophotes of NGC 6876 have at least three different shapes and position angles, depending upon how far out you are from its centre. [ While elliptical galaxies are - at face value - a bit bland in appearance, some of them have very complex isophotal structure in the outline of the galaxy at various radii.]
As I see it, this galaxy has at least three different shapes, depending upon how far out from its centre we display its outline:
- the innermost region is very elongated, and there is some further evidence of other fine structure near the very centre of this galaxy.
- outside of this inner elongated region, the isophotes of this galaxy become very round
- outside of this round zone, there is a vast halo which is noticeably elongated
Moreover, there are hints that many of the elliptical isophotes are not entirely regular.
In the below image, I superpose, in a crude way, lines of equal surface brightness (= isophotes) onto an image of this galaxy from the Chart 32 telescope : :
Attachment 169099
The general structures that are seen here are also visible in several other images that I have analyzed. I am interested, in particular, in the possibility that the outermost isophotes of this galaxy are not regular ellipses.
The innermost few arcseconds of this galaxy are also peculiar, as shown in HST imagery; there is a very unusual two-lobed structure near to the centre of this galaxy.
For instance, here are the isophotes of the central 4 by 4 arsecond region, from an F814W image taken with the HST & WFPC2 : :
Attachment 169100
cheers, Robert