A model of SVC radiation in magnetic dipole field and radiation varying with magnetic field. I - Active region model and SVC radiation source model

Abstract

In our model, the latest EUV data on the chromosphere-corona transition region havebeen used. We have assumed that the plasma conditions above an active region are varyingcontinuously from the centre of the region to the adjacent quiet region. We have taken thethree physical parameters of the plasma (electron temperature and density, and magneticfield) to be functions of both the height above the photosphere and the distance from thecentral axis of the active region. According to the combined mechanism including both the gyroresonance radiation and thebremsstrahlung, using a dipole magnetic field and above-mentioned model of the electrontemperature and density, we have calculated the radio radiation of the slowly varying compo-nent (SVC) and emphatically studied the radiative characteristics of the SVC radiation (suchas the spectra of flux density, polarization degree, and brightness temperaturc, and thebrightness distribution) and the geometrical features of the SVC radiation source (such asheight and radius), and their variations with the magnetic field. Some very interesting resultshave been obtained and they are considerably in agreement with the observations.