Gorban'ova T. Observational constraints of mixing processes in low-mass stars.

High-resolution spectra (R=42000, S/N >100) of 204 stars obtained by the ELODIE spectrograph of the 1.93-m telescope at the Observatoire de Haute Provence (France) were investigated for solve this problem. The atmosphere parameters and elements abundances for the 8 subgiants, 19 disk giants and 177 giants, that were selected as the clump giants using the photometric criteria were determined. We have compared our data with stellar evolution theoretical predictions for low-mass stars. The lithium and carbon abundances undergo a change along the subgiants branch according to the stellar evolution theory. We have estimated a possibility to define the evolutionary status of these giants on the basis of calculated evolutionary tracks and their determined elements abundances that are modified during the stellar evolution. We reliably selected 21 clump giants, about 54 clump candidates and about 100 usual giants that show all the features of first dredge-up. The determined C, N and Na abundances in our programstars reflect the CNO- and NaNe- cycle operation in the giant stars. Others elements abundances show trends similar to those observed in dwarfs. This fact allows us to use these abundances to study the chemical and dynamical evolution of the Galaxy.