Spatial metallicity asymmetry in omega Centauri

The compilation of the metallicity values of omega Centauri stars led to de tection of spatial asymmetry in the metallicity distribution of the bright giants. It was found that the most and the least metal-poor objects are sep arated along Galactic latitude. Statistical tests show that the chance occu rrence of the phenomenon is very low. The subgiant and the RR Lyrae samples do not show, however, similar segregation of the different metallicity obj ects. The physical parameters of the variables calculated by using empirica l formulae indicate that the bulk of the RRab stars comprise a very homogen eous group regarding both their metallicity and mass values. These stars ar e most probably already in the evolved stage of their horizontal branch evo lution.