Omega Centauri is no longer the only globular cluster known to contain multiple stellar populations , yet it remains the most puzzling .
Due to the extreme way in which the multiple stellar population phenomenon manifests in this cluster , it has been suggested that it may be the remnant of a larger stellar system .
In this work , we present a spectroscopic investigation of the stellar populations hosted in the globular cluster \omega Centauri to shed light on its , still puzzling , chemical enrichment history .
With this aim we used FLAMES+GIRAFFE @ VLT to observe 300 stars distributed along the multimodal red giant branch of this cluster , sampling with good statistics the stellar populations of different metallicities .
We determined chemical abundances for Fe , Na , O , and n -capture elements Ba and La .
We confirm that \omega Centauri exhibits large star-to-star variations in iron with [ Fe/H ] ranging from \sim - 2.0 to \sim - 0.7 dex .
Barium and lanthanum abundances of metal poor stars are correlated with iron , up to [ Fe/H ] \sim - 1.5 , while they are almost constant ( or at least have only a moderate increase ) in the more metal rich populations .
There is an extended Na-O anticorrelation for stars with [ Fe/H ] \lesssim - 1.3 while more metal rich stars are almost all Na-rich .
Sodium was found to midly increase with iron over all the metallicity range .