On Hα source function vertical variations in filaments and bright rims visibility

Using new radiative modelling capabilities in twodimensional (2D) cartesian geometry,we investigate the vertical variations of the Hα source function in filaments. It is shown how the two-dimensional geometry can affect the transfer of the Hα line into filaments and, consequently, how assumptions on the geometry of the model may influence a further interpretation of observations. A special attention is paid to the possibility of formation of a bright rim inside the filament body by diffusive penetration of Hα radiation. Unlike recently proposed by Heinzel et al. (1995), we can see from our 2D computations that the observable emergent intensities are not high enough to explain bright rims contrasts.