Hi Dana,
"long time no see".
That's in the UGC catalogue, not in the NGC.
The presence of two or three sub-systems within a galaxy, each of a distinctive age and kinematics and gas content, is not in itself unusual.
A good example of this is IC 5332, recently photographed by IIS members:
http://www.iceinspace.com.au/forum/s...d.php?t=186836
and there are many other galaxies which have this sort of "dual" internal structure, often with an old-aged (= 6-12 billion years old) disk that shows a spiral density wave, together with a young-aged blue-coloured disk structure which has semi-chaotic and open spiral structure.
In other cases, there seems to be a more profound decoupling between two (or even three, in some galaxies!) Different and Distinctive morphological+kinematic+age sub-components of a galaxy, which may well be indicative of a severe (ongoing, or in the past) perturbation.
A tremendous example of this is the Nearly Unclassifiable galaxy NGC 1316, which is Very Similar to an elliptical galaxy in its inner bright parts (albeit the inner region contains a small amount of dust, and also contains subtle low-contrast shells which are of such low contrast that they are hard to measure photometrically), but which also has a much much more Extended and Highly Peculiar component that extends vastly outside of the "elliptical-like" component.....Dr Kenneth Freeman of ANU wrote a paper indicating that this outermost part of N1316 is likely to be a kinematically-cold disk component which is currently (now.....) in the process of being formed in the outermost parts of NGC 1316.
( NGC 1316 has undergone more than one galaxy merger, in its history)
Here's a link to Mike Sidonio's superb pic of N1316::
http://www.iceinspace.com.au/forum/s...d.php?t=187524
But!.....the presence of two distinct and apparently-decoupled morphologies within the same extragalactic system does not have to be, in itself, evidence of a severe perturbation of a galaxy.
However, this sure is a weird (or at least "somewhat weird) galaxy that you have found , as the decoupling between the two evident sub-systems of UGC 12588, at least seems to be much much more evident than is usual in a normal spiral galaxy.
I will have a look , for comparison purposes , at my long-neglected database of 60 thousand galaxy images , as your idea that gas has been stripped from this galaxy by the effects of pressure from the inter-galactic or intra-GalaxyCluster medium has some merit.
But the separation between the two morphological sub-components of this interesting galaxy seems to be too profound for its appearance to be merely the result of gas being stripped from this galaxy. And why would the stripped gas have then formed itself into the pretty spiral pattern which is so very evident?
( one usually observes quite a lot of material which has been stripped from cluster galaxies;
for instance they Very Often lose lots of stars due to gravitational interactions between cluster members, and one does see modest amounts of HII patches that are part of the gas which has been lost by galaxies within galaxy clusters.)
Nonetheless, UGC 12588 may not(!!) actually be very far outside of the normal parameter space for galaxies, if (if!) it is actually a dwarf galaxy;
for instance, the inner component could be a somewhat dusty structure of intermediate-aged stars, and the outer component could simply be a Stochastic (= propagating)(by successive shocks to the interstellar medium) star formation process, leading to a Raggedy (entropic) spiral structure......
common enough in very large numbers of dwarf and low-luminosity galaxies.
Dwarf galaxies are Extremely! easily perturbed, by processes internal and external to a galaxy, so they can often seem to be extremely unusual, at least at first glance, because of the ease with which the interstellar medium, and the stellar body of such a galaxy, can be moved around by relatively modest inputs of energy.
And this galaxy has a Very low radial velocity of recession, in the CMB reference frame, so it is conceivably a nearby dwarf galaxy which is far in the foreground of the galaxy clusters that exist in this part of the sky.
It certainly looks a Whole Lot more normal when the HST image is viewed at large size and high resolution;
https://cdn.spacetelescope.org/archi.../potw2046a.jpg
But this is certainly a galaxy with two very distinct components, and I would very much agree with your proposition that both of the components have a very distinctive and very interesting look!!
P.S.
You are right that this galaxy might conceivably be on its "last gasp"when it comes to its ongoing star formation, leading eventually to the formation of a quiescent S0 morphology.
So, maybe......
here we are looking at the formation of a dwarf S0 galaxy?!?!?
P.P.S.
I do believe that we might conceivably find other galaxies that look like this, if we look in amongst the population of low-luminosity galaxies.
(As they are an incredibly diverse bunch.......
There are several Brand New (= recently posited) morphological classes of dwarf galaxies that I do not even know about, as my eyes have resolutely been pointed Down To The Ground for several years, especially towards fossils of the Ediacaran Geological Period!
So my suggestion is that we do try to assign a Hubble Class for this galaxy;
that is, to force this galaxy to fit into one of the existing (known) morphological classes of galaxy (e.g. Dwarf Sd/S0, dwarf S0, Sd, Sdm, Sm, BCD, etc), but then, if this doesn't work out, maybe to conclude that there is really and truly something weird going on here!!
But Orthodox galaxy classification can fail for dwarf galaxies.
(It was always based on galaxies of intermediate to high luminosity, though many are attempting to extend it to the dwarf end, with variable amounts of success)
I think some dwarfs could, for instance, be of a Mixed galaxy type of Irregular and also(!) Elliptical (E + Irr, E/Irr) . So maybe better to try to look at each galaxy as being the sum of various morphological components.
For instance, if we look in the SIMBAD galaxy database and then go to the ''Aladin Lite' image viewer , so as to view an image this galaxy, the PanSTARRS/Dr1 image appears to show an old (or oldish) stellar body of a roughly spheroidal appearance (though of course the 3-D morphology is highly uncertain) together with a highly-entropic (but organized) spiral structure.......= Hubble type E/Sd ?!?!?
(but of course Hubble himself knew little or nothing of the detailed morphology of these dwarfs. It was his disciples who extended the sequence to these systems)
[[[ Nonetheless, if this is a non-dwarf galaxy, then we would be looking at a different proposition!
( I do think it is likely to be a low luminosity galaxy)
]]]