Parsec-scale Properties of eight Fanaroff-Riley Type 0 Radio Galaxies
  We report the high-resolution radio observations of eight Fanaroff-Riley type
0 radio galaxies (FR 0s), selected from the published FR 0 sample. These
observations were carried out with the Very Long Baseline Array (VLBA) and
European VLBI Network (EVN) at frequencies of 5 and 8 GHz with a highest
resolution of 0.6 mas. All eight sources show compact structures on projected
physical sizes of 0.3-10 parsec. Six sources show a two-sided structure and two
sources show a one-sided jet structure. J1025+1022 shows an X-shaped jet
structure, which could result from a reorientation of the jet axis due to a
restart of the central engine or a projection of a highly curved inner jet, but
more studies are needed to examine these scenarios. Proper motions for 22 jet
components of the eight sources are determined to be between -0.08 c and 0.51
c. Although most of the sources exhibit flat spectra, other observed
characteristics, such as, low-amplitude flux density variations, low jet proper
motion speeds, and symmetric two-sided jet structures, tend to support that the
pc-scale FR 0 jets are mildly relativistic with lower bulk Lorentz factors and
larger viewing angles.
