The radio corona of AR lacertae

We present multifrequency VLA and VLBA observations at 8.4 GHz of the RS CV n system AR Lac, that were performed in autumn 1997 simultaneously with X-r ay observations obtained from Rodono et al. (1999). Our VLBA data indicate a resolved source with dimension close to the system separation, while the study of the flux density curve reveals a small amplitude outside of the ec lipse variability. The derived five-frequencies spectra, combined with the size information from VLBA data, are compared with gyrosynchrotron emission from a two component structured source. A comparison with the results of t he X-ray observations allow us to exclude the possibility that a thermal gy rosynchrotron is responsible for the radio emission, but it is compatible w ith the hypothesis of co-spatial X-ray and radio emitting sources.