We compute surface brightness profiles of galactic disks for outwardly propagating waves of star formation with a view to investigate the stellar populations in ring galaxies .
We consider two mechanisms which can create outwardly propagating star forming rings in a purely gaseous disk — a self-induced wave and a density wave .
We show that the surface brightness profiles produced by both scenarios of ring formation are similar and are strongly sensitive to the velocity of the wave .

The results of our computations are compared with the observational quantities sensitive to the young and old stellar populations in the ring galaxies A0035-335 ( the Cartwheel galaxy ) and VII Zw466 .
The best fit to the observed radial H \alpha surface brightness distribution in the Cartwheel galaxy is obtained for a wave velocity of about 90 km/s .
The red continuum brightness of the ring can be fully explained by the evolving stars present in the trailing part of the wave .
However the red continuum brightness in regions internal to the ring indicates that the wave of star formation propagates in a pre-existing stellar disk in the Cartwheel .
The H \alpha and K -band surface brightness profiles in VII Zw466 match the values expected from stellar populations produced by a wave of star formation propagating in a purely gaseous disk very well .
We conclude that VII Zw466 is probably experiencing the first event of star formation in the disk .