Downsizing in HII galaxies

In this work we estimated the statistical age of a set of HII galaxies obtained from the Sloan Digital Sky Survey Data Release Three (SDSS DR3). Applying an inversion method to the observed distribution of an age sensitive parameter such as the equivalent width of (Hα), we estimate the age of the galaxies. We find strong dependence of the age with stellar luminosity, mass and metallicity with the youngest HII galaxies being those with the lowest mass and metallicity. These dependences found among HII galaxies indicate that "downsizing" extends to the low end of the mass distribution of galaxies.