THE ORIGIN OF THE QUASI-STELLAR OBJECT ABSORPTION-LINES

In recent years, several results concerning the QSO absorption-line systems indicate the possibility that they may be associated with star-forming regions in intervening galaxies. In this paper, we explore the hypothesis that the metal absorption lines are produced in H II regions of intervening galaxies. Our method of analysis is mainly based on the C IV and Si IV absorption lines. A comparison between observed and calculated equivalent widths fix the characteristics of the absorbing H II region (ionizing star, gas density, and chemical abundances). The calculated equivalent widths are obtained from column densities given by photoionization models. The column densities are calculated for different lines of sight crossing the H II region at different distances from the star. The analysis of 20 absorption line systems shows that H II regions in intervening galaxies can be the origin of the metal-line absorption systems. This model provides promising consequences concerning star formation rates and chemical evolution of galaxies.