The data presented in this paper demonstrate that massive star clusters are formed not only in starburst galaxies, but also in rather normal galaxies. None of the galaxies in our sample show obvious signs of having been involved in interaction processes, yet we find that there is a large variation in the specific frequency of massive clusters from one galaxy to another. Some of the galaxies in our sample (notably NGC 1313 and NGC 5236) have considerably higher than the LMC, while other galaxies which at first glance could seem in many ways morphologically similar to the LMC (e.g. NGC 300 and NGC 4395) turn out to contain no rich cluster systems. In general there is no correlation between the morphological type of the galaxies in our sample and their values. Whether a galaxy contains massive star clusters or not is therefore not only a question of its morphology (as suggested by Kennicutt & Chu 1988), so one has to search for correlations between other parameters and the values. Within each of the galaxies that contain populations of YMCs, the number of clusters as a function of radius follows the H surface brightness more closely than the broad-band surface brightness, which implies that the formation of massive clusters in a given galaxy is closely linked to star formation in general.
© European Southern Observatory (ESO) 1999
Online publication: April 12, 1999