Circumstellar envelope manifestations in the optical spectra of evolved stars

We consider the peculiarities of the optical spectra of far evolved stars with circumstellar gaseous-dusty envelopes: the time variability of the absorption-emission profiles of the H$α$ line, the presence of stationary emission and absorption molecular bands, multicomponent complex profiles of the NaI D-doublet lines. We show that the peculiarities of the line profiles (the presence of an emission component in the NaI D-doublet lines, the specific type of the molecular features, the asymmetry or splitting of the profiles of strongest absorptions with low excitation potential of the low level) can be associated with the kinematic and chemical properties of the circumstellar envelope and its morphological type.

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