Population Synthesis in Starburst Galaxies - MARKARIAN:710

Evolutionary population synthesis models have been built to study the properties of the starforming processes taking place in starburst regions. BothZ_⊙ andZ_⊙/10 stellar evolutionary tracks have been used to take into account that starburst galaxies are generally metal deficient. A very small time step allows us to follow the evolution of the cluster even during very short phases. Three parameters have been synthesized: the ratio of the SiIV (1400 Å) andCIV (1550 Å) UV absorption lines, that characterize the predominant massive stars in the cluster, the ratio of the WR_bump over the Hβ luminosity, tracer of WR stars and the FIR luminosity, directly related to the extinction due to dust in the cluster. The predictions have been compared with observations of the burst taking place in the galaxy Mkn 710. The burst age is 5–6 Myr. The stars seem to have formed simultaneously with a mass spectrum whose slope is in the range (1,2) for massive stars. The upper mass limit has to be ≥60M_⊙. We have performed a systematic study of a sample of 17 starburst galaxies searching for differences in the star formation process that may be related to different metallicities or morphological types.