Abstract
An original method of estimating the projected rotational velocity, vsini, and the macroturbulent velocity, vmac, of evolved M giant stars is presented. It is based on the use of spectrum synthesis and multiline analysis tools. The goal is to fit the mean line profile of observations with that of synthetic spectra. The method is applied to the red giant star RZ Ari, and the results vsini = 6.0 ± 0.5 km s−1 and vmac = 2.0 ± 1.0 km s−1 are obtained.