The subgiant branch of ω Centauri seen through high-resolution spectroscopy - I. The first stellar generation in ω Cen?E. Pancino, A. Mucciarelli, L. Sbordone, M. Bellazzini, L. Pasquini, L. Monaco and F. R. FerraroA&A, 527 (2011) A18DOI: https://doi.org/10.1051/0004-6361/201016024
