Physical conditions in the central molecular zone inferred by H3+ Franck Le Petit, Maxime Ruaud, Emeric Bron, Benjamin Godard, Evelyne Roueff, David Languignon and Jacques Le Bourlot A&A, 585 (2016) A105 Published online: 05 January 2016 DOI: 10.1051/0004-6361/201526658