Chromospheric Models in ω Centauri Red Giant Stars

Mass loss of ∼ 0.1-0.3 M_⊙ from Population II red giant stars is a requirement of stellar evolution theory in order to account for several observational evidences in globular clusters. The aim of this study is to detect the presence of outward velocity fields, that are indicative of mass outflow, in six luminous red giant stars of the stellar globular cluster ω Cen. We compare synthetic line profiles computed using relevant model chromospheres to observed profiles of the Hα and Ca II K lines. We do indeed reveal the presence of low velocity outward motions in four of our six targets, with no apparent correlation with astrophysical parameters.