Star formation in dwarf galaxies

We explore mechanisms for the regulation of star formation in dwarf galaxie s. We concentrate primarily on a sample in the Virgo Cluster, which has H I and blue total photometry, for which we collected H alpha data at the Wise Observatory. We find that dwarf galaxies do not show the tight correlation of the surface brightness of H alpha (a star formation indicator) with the H I surface density, or with the ratio of this density to a dynamical time scale, as found for large disk or starburst galaxies. On the other hand, we find the strongest correlation to be with the average blue surface brightn ess, indicating the presence of a mechanism regulating the star formation b y the older (up to 1 Gyr) stellar population if present, or by the stellar population already formed in the present burst.