Mass loss and luminosities of S and C AGB stars with and without Li

We present the preliminary results of an analysis performed on two samples of thermally pulsing Asymptotic Giant Branch stars from our Galaxy, the first made of carbonrich sources and the second of S-type stars. We have estimated their absolute luminosities and updated rates of the stellar winds through methods based on their infrared spectrophotometry and on updated estimates of their variability and distance. We then focus on those sources in our database showing Li in their spectra looking for correlations between the Li abundance and the other physical parameters, in the aim of establishing observational criteria for understanding the conditions for the occurrence of the deep mixing phenomena to which the production of Li is currently attributed.