Propagation of star formation at sub-kiloparsec scales
  We study the propagation of star formation based on the investigation of the
separation of young star clusters from HII regions nearest to them. The
relation between the separation and U-B colour index (or age) of a star cluster
was found. The average age of star clusters increases with the separation as
the 1.0-1.2 power in the separation range from 40 to 200 pc and as the 0.4-0.9
power in the range of 100-500 pc in the galaxies with symmetric morphology. The
galaxies with distorted asymmetric disc structure show more complex and steeper
(power >1.2 at separations from 40 to 500 pc) dependence between the age and
the separation. Our results confirm the findings of previous studies on the
dominant role of turbulence in propagation of the star formation process on
spatial scales up to 500 pc and on time scales up to 300 Myr. On a smaller
scale (=<100 pc), other physical processes, such as stellar winds and supernova
explosions, play an important role along with turbulence. On the scale of
stellar associations (100-200 pc and smaller), the velocity of star formation
propagation is almost constant and it has a typical value of a few km/s.
