Interstellar-cloud formation in the extended envelopes of blue compact dwarf galaxies

Blue compact dwarf galaxies (BCDs) have an interesting feature in their cen tral region where stars are actively forming. In this paper, we show that s hock waves produced by the starbursts there are able to trigger self-gravit ating interstellar clouds in extended envelopes, which are often observed i n typical BCDs. The criterion adopted for the formation of interstellar clo uds is very simple, that is, rho > 2 Gamma<(<rho>)over bar>/3. Here, rho is the gas density of the shocked layer, <(<rho>)over bar> is a mean density including the dark matter, and r is a numerical factor between 0.5 and 1.0, depending on the mass distribution of the galaxy. Hence, we suggest that t he infalling of the clouds onto the central regions causes subsequent starb ursts after similar to 0.1 Gyr of the event, and that the episodic starburs ts continue during sub-Gyr.