Uv Hst Spectroscopy of Star-forming Galaxies

to be published in the " Starburst Activity in Galaxies " proceedings by the RevMexAstronAstrofis. ABSTRACT HST spectroscopical observations of 8 HII galaxies are reported. Lyα emission was detected in 4 of them. We find that it is the velocity structure of the gas which is the main determining factor for the escape of the Lyα photons, and not the abundance of dust. The rest of the sample shows broad damped Lyα absorption attributed to large HI column densities that is static with respect to the emitted Lyα photons emerging from the HII regions. The star-forming galaxies IZW18 and even more SBS0335–052 may have extremely metal deficient HI clouds, the latter with [O/H] as low as-7.2.