New Abundances for Old Stars - Atomic Diffusion at Work in NGC 6397
  A homogeneous spectroscopic analysis of unevolved and evolved stars in the metal-poor globular cluster NGC 6397 with FLAMES-UVES reveals systematic trends of stellar surface abundances that are likely caused by atomic diffusion. This finding helps to understand, among other issues, why the lithium abundances of old halo stars are significantly lower than the abundance found to be produced shortly after the Big Bang. 
A.J. Korn (1), F. Grundahl (2), O. Richard (3), P.S. Barklem (1), L.   Mashonkina (4), R. Collet (1), N. Piskunov (1), B. Gu...