Properties of a Chemically Enriched Lya Absorption System at z=0.167 and Implications for the Total Baryons in Extended Gaseous Envelopes Around Galaxies

Abstract

We present a detailed analysis of the chemical abundances, ionization state, and origin of a partial Lyman limit system (N(HI) ~ 10^{16} cm^{-2}) at low redshift (z=0.167 towards PKS0405-1219). We also present the first estimate of the total baryons in extended gaseous envelopes around galaxies based on a simple photoionization model for the Lya absorbers. We find that extended gaseous envelopes can explain between 5--20% of the total baryons predicted by the big bang nucleosynthesis model.

10 pages, 4 figures, to appear in ``Extragalactic Gas at Low Redshift'', ed. J. Mulchaey and J. Stocke, ASP Conf. Serie