Methyl cyanide as tracer of bow shocks in L1157-B1 C. Codella, M. Benedettini, M. T. Beltrán, F. Gueth, S. Viti, R. Bachiller, M. Tafalla, S. Cabrit, A. Fuente and B. Lefloch A&A, 507 2 (2009) L25-L28 Published online: 27 October 2009 DOI: 10.1051/0004-6361/200913340