[madbadgalaxyman (Robert)]

Originally Posted by marco

Actually I am more t extreme linear stretch on the reversed B&W luminance and I have to say that I get the impression that more than shell here we have extremely faint spiral arms..
Regards
Marco

Marco,

The surface brightness of the outermost features in IC 1459 is exceedingly low, so you have done very good work to show them even faintly. Your image of this galaxy is quite comparable to one that David Malin made with the UK Schmidt, and he had to stack several photographic plates to make his image.

Actually, "arm-like" features are sometimes found in elliptical-galaxy-like galaxies that have experienced merger with other galaxies (e.g. in NGC 1316.)
However, they usually look more like "ripples" or "waves" than actual spiral arms.....

Here are some examples:

(1) Messier 85 (this image from SDSS)


(2) NGC 467 (which you imaged)

(3) NGC 2655 (Carnegie Atlas image)


(4) NGC 2782 (SDSS image)


(5) NGC 3205 (SDSS image)


(6) NGC 7727


The interest of some of these galaxies is that there is the possibility that an orthodox (usual appearance) disk and spiral arms could currently be in the process of formation.

See this interesting paper which makes the provocative hypothesis that NGC 1316 is actually a young Sombrero Galaxy in the process of formation:
http://adsabs.harvard.edu/abs/2012A%26A...539A..11M

This is a distinct and unique type of morphology which is not so rare amongst the bright galaxy population, and it is not on the ordinary Hubble sequence of galaxy morphologies.
(E - S0 - S0/a - Sa -Sb - Sc - Sd - Sdm - Sm - Irr)