There is a blue ring (stars forming?). Are rings a phase in a galaxy's evolution? Does it eventually evolve to a different shape? Has it evolved from some other shape?
by ElisabethB moderator
Wow ! Beautiful ring/ringed galaxy. The blue smudges are star forming areas in the galaxy.
by KWillett scientist, admin, translator
Rings can be a natural phase in the evolution of a galaxy, although they're usually not very common. You can either have regular ring galaxies, in which a ring of stars/gas orbits in the same plane as the disk (like Hoag's Object):
Or polar ring galaxies, in which the orbiting material goes perpendicular to the disk and around the poles of the galaxy:
The ring structures are probably pretty short-lived; it probably looked like a more standard disk galaxy with spiral arms. The burst of star formation will decrease over time, however: here's a neat movie showing the results of a dynamical simulation of a similar source. You can see the ring galaxy being created by the initial merger, and then the ring expanding outward while the bulges of the original galaxies completely merge.