Dual-frequency and dual-polarization VLBI observations of the stellar system Algol

Results of multiepoch VLBI observations of the stellar system Algol are presented, including dual-polarization and dual-frequency measurements at 2.3 and 8.4 GHz. The brightness temperature of the radio source is generally between 3 x 10 to the 8th K and 5 x 10 to the 9th K and is consistent with gyrosynchrotron emission from energetic electrons with mean energy less than 1 MeV in an active coronal region. Two exceptional events were observed: a high-brightness, broad-band outburst occurring simultaneously at 2.3 and 8.4 GHz, and a short-duration, highly polarized and high-brightness temperature outburst at 1.66 GHz. A simple physical model which includes all three types of emission is suggested.