Milky Way versus Andromeda: a tale of two disks J. Yin, J. L. Hou, N. Prantzos, S. Boissier, R. X. Chang, S. Y. Shen and B. Zhang A&A, 505 2 (2009) 497-508 Published online: 03 August 2009 DOI: 10.1051/0004-6361/200912316