THE COMPACT TRIPLES 0710+439 AND 2352+495 - A NEW MORPHOLOGY OF RADIO GALAXY NUCLEI

The compact radio sources 0710 + 439 and 2352 + 495 have each been mapped using intercontinental VLBI arrays at frequencies of 5.0 and 10.7 GHz. The source 0710 + 439 has also been mapped at 1.7 GHz. Both sources consist of three principal components that lie almost on a straight line. Except for the existence of three VLBI components instead of two they both seem to have similar properties to members of the compact double class. Multi-epoch observations show that apparent velocities between the components in both sources are below c. In the source 0710 + 439 comparison of multi-epoch data allows us to set a limit of 0.054 +/- 0.14 h-1 c on the rate of separation of the two brightest components. In 2352 + 495 the multi-epoch 5 GHz VLBI data show that the flux density variations detected by total flux density monitoring are due to changes within the middle component. These fluctuations may be due to refractive interstellar scintillation or they may be intrinsic to the source; in either case the middle component must contain the most compact structure within the source. The morphology, spectra and variability of the middle components strongly suggest that the center of activity in both sources lies here rather than in either of the outer components, providing the first clear evidence of symmetric radio structure in a powerful active galaxy nucleus.