INITIAL MASS FUNCTION IN STARBURST GALAXIES WITH DIFFERENT METALLICITY

Abstract

We present an analysis of the massive stellar population in 8 starburst galaxies and 4 blue compact galaxies based on the equivalent widths of the UV p-cygni lines Si IV lambda-1400 A and CIV-lambda-1550 A reported (in part) by Sekiguchi and Anderson (1987a,b). These lines are characteristic of early OB stars and represent good indicators of the massive stellar content. Based on this analysis we estimate the mean ionizing effective temperature (Tioniz) and compare these results with photoionization models. Our method indicate larger values (approximately 8%) for (Tioniz). We estimate the metallicities using different methods. The photoionization models indicate larger metallicities than those derived by the other methods. We also found that in the lower metallicity stellar systems there is a larger proportion of massive stars or a larger upper mass limit for the present day mass function. This second possibility seems to agree better with photoionization models.