An alternate possibility is a relatively recent burst of star formation in the inner galaxy, probably within the last 10 million years. (scientificamerican.com)
It doesn't have gigantic regions of star formation in its arms, it doesn't have a rectangular bar in its center, it doesn't appear to have large satellite galaxies. (discovermagazine.com)
The energetic processes of star formation create not only the colors but the chaos. (apod.nasa.gov)