M83 is a magnificient spiral galaxy with well defined spiral arms, and
displaying a very dynamic
appearance, appealing by the red and blue knots tracing the arms.
The red knots
are apparently diffuse gaseous nebulae in which star formation is just taking
place, and which are excited to shine by its very hot young stars. The blue
regions represent young stellar populations which have formed shortly (i.e.,
some million or some dozens of million years ago).
Between the pronounced spiral
arms are regions with fewer stars. Dark dust lanes follow the spiral structure
throughout the disk, and may be traced well into the central region to the
nucleus, which has only 20 arcseconds diameter (less than 1/100 of the full moon).
The nucleus is composed of an older yellowish stellar population which dominates the
whole central region, and extends along the barlike structure.