Title: Chemical tagging of moving groups in the solar neighborhood: the omega Centauri 
connection

Abstract:
The study of the substructures that live within the solar neighborhood today would produce 
valuable constraints on the working of hierarchical assembly of the Milky Way. However, the 
kinematic association of stars does not uniquely imply a stellar stream. In fact, the Galactic 
halo is known to harbor many moving groups, which are coherent substructures in phase-space. 
The validation of a moving group as a stellar stream requires a detailed chemical abundances 
study as well, which may allow to identify the possible progenitor for a given tidal debris 
candidate. One of the proposed progenitors of several known substructures, overdensities 
and moving groups is the globular cluster omega Centauri, thought to be the remnant nucleus of 
a dwarf galaxy accreted by the Milky Way at some time in the past. If they are really tidal 
debris of omega Centauri, stars in these groups should show some of the well-established 
specific chemical abundance patterns known for stars currently belonging to the cluster, such 
as the Na-O and Mg-Al anti-correlations. Moreover, unless only first generation stars were 
selectively stripped from the cluster, it would be reasonable to expect some star to be enhanced 
in their helium content. I will present the results of an optical and near-infrared analysis of 
stars belonging to three separate moving groups (including the famous Kapteyn group) that have 
been associated to omega Centauri based on kinematics and limited chemical abundance 
measurements.