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Yeah, those diagrams in the astronomy textbooks are wrong; you know, those diagrams showing a spiral galaxy as a thin flat and planar object!
Thin and flat, yes, but planar....NO!
In fact, strict planarity is rare in disk galaxies.
I have prepared an Atlas of edge-on S0 and Spiral galaxies that show a bewildering variety of non-planar bends, warps, and tilts. There are about 4 types of warp that are recognized in the scientific literature, but this is only a fraction of the various types that exist in the real universe.
A third possibility for the actual 3-dimensional structure of what we observe (in two dimensions only) in the outermost regions of NGC 2841 would be a detached ring that surrounds the bright optical body of this galaxy, but which is well separated from the main optical body.
Polar rings are a well-known and well-studied phenomenon in galaxies, but regarding the existence (and plausibility) of Outermost detached rings that are in a similar plane to the rest of a galaxy.......
I don't think anyone knows what is the actual incidence of these objects, but with the new trend towards ultra-deep imaging by amateurs, we will soon find out.
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