Author(s): , , ,
Institution(s): 1. Institute of Astrophysics, Pontificia Universidad Catolica de Chile, 2. McDonald Observatory and Department of Astronomy, 3. Universidad Andrés Bello
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.