The onset of energetic particle irradiation in Class 0 protostars C. Favre, A. López-Sepulcre, C. Ceccarelli, C. Dominik, P. Caselli, E. Caux, A. Fuente, M. Kama, J. Le Bourlot, B. Lefloch et al. (4 more) A&A, 608 (2017) A82 Published online: 08 December 2017 DOI: 10.1051/0004-6361/201630177