The white-dwarf cooling sequence of NGC 6791: a unique tool for stellar evolution E. García-Berro, S. Torres, I. Renedo, J. Camacho, L. G. Althaus, A. H. Córsico, M. Salaris and J. Isern A&A, 533 (2011) A31 Published online: 23 August 2011 DOI: 10.1051/0004-6361/201116499