Chemical composition of stellar populations in ω Centauri

We derive abundances of Fe, Na, O, α and s-elements from GIRAFFE@VLT spectra for more than 200 red giant stars in the Milky Way satellite ω Centauri. Our preliminary results are that: (i) we confirm that ω Centauri exhibits large star-to-star metallicity variation (~1.4 dex); (ii) the metallicity distribution reveals the presence of at least five stellar populations with different [Fe/H]; (iii) a distinct Na-O anticorrelation is clearly observed for the metal-poor and metal-intermediate stellar populations while apparently the anticorrelation disappears for the most metal rich populations. Interestingly the Na level grows with iron.