The Lyman alpha forest towards B2 1225 + 317

We present observations of the Lyman alpha forest towards B2 1225+317 takenat a resolution of 18 km/s. A clean sample of Lyman alpha forest lines isextracted after a careful profile fitting analysis and removal of absorptionlines of heavy elements. The sample is analyzed for statistical properties.Eighty percent of the column densities are < 10^{14} cm^{-2}. A single powerlaw is inconsistent with the column density distribution and a steepening/breakin the distribution is indicated. The average velocity dispersion parameter is29.4 km/s. We find 3 sigma evidence for a correlation between column densityand the velocity dispersion parameter. The correlation, however, is mainly dueto narrow lines and weakens to 1.2 sigma if lines with velocity dispersionparameter smaller than 20 km/s are excluded. An excess of line pairs withvelocity separation $\le$ 100 km/s over the expected number is found.Comment: latex(mn.sty), 6 figures (available on request from anand@iucaa.ernet.in or khare@iopb.ernet.in), to appear in MNRA