Modelling a set of C-rich AGB stars: the cases of RU Vir and R Lep

We study the atmospheres of a set of carbon-rich asymptotic giant branchAGB stars to improve our understanding of the dynamic processeshappening there. We compare in a systematic way spectrometric,photometric and mid-infrared (VLTI/MIDI) interferometric measurementswith different types of model atmospheres: (1) hydrostatic models +MOD-dusty models added a posteriori; (2) self-consistent dynamic modelatmospheres. These allow us to interpret in a coherent way the dynamicbehavior of gas and dust. The results underline that the joint use ofdifferent kinds of observations, as photometry, spectroscopy andinterferometry, is essential for understanding the atmospheres ofpulsating C-rich AGB stars. For our first target, the carbon-rich Mirastar RU Vir, the dynamic model atmospheres fit well the ISO/SWS spectrumin the wavelength range lambda = [2.9, 13.0] μm. However, the objectturned out to be somehow ''peculiar''. The other target we present is RLep. Here the agreement between models and observations is much betteralthough the MIDI data at 11.4 μm cannot be properly modelled.