Renewed Radio Activity of Age 370 years in the Extragalactic Source 0108+388

Abstract

We present the results of multi-epoch global VLBI observations of the Compact Symmetric Object (CSO) 0108+388 at 5 GHz. Analysis of data spread over 12 years shows strong evidence for an increase in the separation of the outer components at a rate of $0.197\pm0.026 h^{-1}c$. Given an overall size of 22.2 $h^{-1}$pc this implies a kinematic age of only $367\pm48$ yrs. This result strongly supports the idea that radio emission in Compact Symmetric Objects arises from recently activated radio sources. The presence of weak radio emission on kpc-scales in 0108+388 suggests recurrent activity in this source, and that we are observing it just as a new period of activity is beginning.