Theoretical Multi-Frequency Solar Radii and Limb Brightening

Theoretical works show the solar limb brightening at radio – sub-millimeter wavelengths as opposed property to the solar limb darkening at visible range of the electromagnetic spectrum. Nowadays, there is not a consistently study in the wide radio-infrared electromagnetic regions. In this work, we present a detailed study of the solar limb brightening from 2 GHz to 10 THz using PakalMPI code to solve the radiative transfer equation in a 3D geometry. We found the theoretical region of expected maximum limb brightening and compute the theoretical solar radii at the same frequencies.