A study of the color diversity around maximum light in Type Ia supernovae R. Cartier, F. Förster, P. Coppi, M. Hamuy, K. Maeda, G. Pignata and G. Folatelli A&A, 534 (2011) L15 Published online: 18 October 2011 DOI: 10.1051/0004-6361/201117778