Velocity dispersions of elliptical and S0 galaxies. I - Data and mass-to-light ratios. II - Infall of the local group to Virgo

The method of dispersion calculation employed in the reported investigation uses cross-correlation against a filtered template. It is a linear process that does not require nonlinear least-square parameter estimation. A description is given of tests which were performed to check the accuracy of the conducted measurements. Dispersion estimates are presented for 373 elliptical and S0 galaxies. Mass-to-luminosity ratios are computed, and the obtained global values are compared to core values of M/L derived by Schechter (1980). Plots are presented of M/L versus luminosity, dispersion, and equivalent width. The observed M/L ratio shows no correlation with luminosity, although the luminosity varies by a factor of 100. This is evidence that the stellar population within elliptical galaxies is relatively insensitive to the size of the galaxy. The question of correlations between various observable parameters of elliptical galaxies is investigated, and the relationship is exploited between absolute luminosity and velocity dispersion to measure the infall velocity of the Local Group toward the Virgo supercluster.