On the possible importance of coherent resonant scattering in the solar transition region. A study of the C IV 154.8; 155.0 nm doublet.

We study the importance of resonant, coherent scattering of photons, in the C IV 154.8 and 155.0 nm spectral lines formed in the solar transition region. We show that under the effect of coherent scattering, the two lines of the doublet can present different spectral shapes as found in some solar and stellar observations which have not yet been explained. In order to model the combination of resonant scattering and opacity effects we simulate the spectral profiles of the C IV lines using Monte Carlo methods. Finally we present estimations of the importance of resonant scattering with respect to electron collisions inherent in the Differential Emission Measure function, a diagnostic tool much used for transition region plasma.