Spatial metallicity asymmetry in ω Centauri

The compilation of the metallicity values of omega Centauri stars led to detection of spatial asymmetry in the metallicity distribution of the bright giants. It was found that the most and the least metal-poor objects are separated along Galactic latitude. Statistical tests show that the chance occurrence of the phenomenon is very low. The subgiant and the RR Lyrae samples do not show, however, similar segregation of the different metallicity objects. The physical parameters of the variables calculated by using empirical formulae indicate that the bulk of the RRab stars comprise a very homogeneous group regarding both their metallicity and mass values. These stars are most probably already in the evolved stage of their horizontal branch evolution.