VLBI observations of a complete sample of radio galaxies: 10 years later

A complete sample of 27 radio galaxies was selected from the B2 and 3CR catalogs in order to study their properties on the milliarcsecond scale. In the Appendix of this paper we present new radio images for 12 of them. Thanks to the present data, all the sources in this sample have been imaged at milliarcsecond resolution. We discuss the general results. In particular we stress the evidence for high-velocity jets in low-power radio galaxies, compare high- and low-power sources, and discuss the source properties in light of the unified scheme models. We conclude that the properties of parsec-scale jets are similar in sources with different total radio power and kiloparsec-scale morphology. From the core-total radio power correlation, we estimate that relativistic jets with Lorentz factor gamma in the range 3-10 are present in high- and low-power radio sources. We discuss also the possible existence of a two-velocity structure (fast spine and lower velocity external shear layer).