Ionization fraction and the enhanced sulfur chemistry in Barnard 1 A. Fuente, J. Cernicharo, E. Roueff, M. Gerin, J. Pety, N. Marcelino, R. Bachiller, B. Lefloch, O. Roncero and A. Aguado A&A, 593 (2016) A94 Published online: 29 September 2016 DOI: 10.1051/0004-6361/201628285