The recent history of star formation in the BCD galaxy VII Zw403, is analysed with accounts for the dynamics of the remnant generated either by an instantaneous burst or by a continuous star formation event. We have re-observed VII Zw403 with a better sensitivity corresponding to the threshold H$_{ \alpha}$ flux $8.15 \times 10^{ -17}$ erg cm$^{ -2}$ s$^{ -1}$. The total H$_{ \alpha}$ luminosity derived from our data is much larger than reported before, and presents a variety of ionized filaments and incomplete shells superimposed on the diffuse H$_{ \alpha}$ emission. This result has a profound impact on the predicted properties of the starburst blown superbubble. Numerical calculations based on the previous H$_{ \alpha}$ data, predict two different scenarios of star formation able to match simultaneously all observed parameters. These are an instantaneous burst of star formation with a total mass of $5 \times 10^5$ M$_{ \odot}$ and a star-forming event with a constant SFR = $4 \times 10^{ -3}$ M$_{ \odot}$ yr$^{ -1}$, which lasts for 35 Myrs. The numerical calculations based on the energy input rate derived from our observations predict a short episode of star formation lasting less than 10 Myrs with a total star cluster mass $\sim (1 - 3) \times 10^6$ M$_{ \odot}$.
Categories: astro-ph