[madbadgalaxyman (Robert)]

Marco,

As has become the normal thing in most of your astro images, there is something on your image which is potentially of astrophysical interest; due to the depth and resolution that you always do achieve in your images.

The centralmost feature of dust lanes in M31 looks like a ring ; the dust lanes spiral inwards, but they actually do form a ring structure.

In my view, if this inner dust feature were at the same orientation (the same angle to our line-of-sight) as the rest of M31, the central dust lanes would make a completely different pattern than the actual dust pattern that we do observe.

The overall dust lanes seen in M31 are foreshortened due to the orientation of the disk of this galaxy, but the central dust ring does not look foreshortened!!

The way I interpret this hypothetical dust ring is that the inner dust ring is actually in a different plane to the rest of M31.
Indeed, this is one strange galaxy, and it has had multiple interactions with other galaxies in its past.
Various subtle non-planarities are very common within M31!

The central dust feature is, without doubt, an unusual one.

Note added in an edit:
One of the more interesting observations that is within the positional accuracy possible with the Hubble Space Telescope is to measure the proper motions of M31 and its satellites. In other words, while extragalactic astronomers generally have access only to the radial motion of a galaxy (its motion in our line-of-sight), by means of its velocity as can be derived from its spectrum, it is currently feasible to measure the motions "across the sky" (at right angles to the line-of-sight) of galaxies in our Local Group of Galaxies. This remarkable feat would then enable us to get accurate orbits for many nearby galaxies such as M32 and NGC 205; some people think that a lot of the strange and unusual features of M31 are due to the effects of its satellite galaxies.