1995A&A...300..643C

We present total intensity and polarization data of three B2 radio galaxies with of radio luminosity in the range P_1.4=10^24.6-10^24.8 W.Hz^–1, intermediate between FRI and FRII objects. The sources were observed at 6 and 20cm in different configurations of the VLA. We discuss the morphology, the polarization and the spectral properties of these objects and particularly of their jets. In certain aspects their behaviour is intermediate between the FRI or FRII radio galaxies, leading to the conclusion that they are transition objects between the two classes. In two of these sources depolarization and rotation measure analysis clearly display the Laing-Garrington effect. Spectral steepening in the the low brightness regions leads to an estimate of the ages of the sources. From energy arguments and from the asymmetry in the jet brightness, we estimate that velocities in the jets are of the order of 0.5c-0.7c in the first 5kpc and then decrease to ≲0.2c at ≳20kpc from the core. The jet Mach numbers are estimated in the range of 4-6.