FLARING AND QUIESCENT RADIO-EMISSION OF UX ARIETIS - A TIME-DEPENDENTMODEL

Two different interpretations of the quiescent radio emission of UX Ar i are considered and compared with available observations. It is assum ed that the radiation mechanism is gyrosynchrotron and that the emitti ng electrons are distributed according to (1) a Maxwellian distributio n at the same temperature deduced from X-ray observations (T congruent -to 5 x 10(7) K); and (2) a power-law distribution with different expo nents. Both electron populations can reproduce the observed spectrum, provided that a suitable configuration of the magnetic field is assume d. The time evolution of a population of electrons following an initia l power-law distribution is also studied. It is shown that the spectru m of the emitted radiation evolves, in a time scale of a few days, fro m the typical spectrum of the flaring emission to the flat one observe d in quiescent periods. It is also shown that the intensity distributi on reproduces the core-halo structure observed by Mutel et al. (1985) using VLBI for a period of approximately 1 day after the flare.