High-mass star formation at sub-50 au scales H. Beuther, A. Ahmadi, J. C. Mottram, H. Linz, L. T. Maud, Th. Henning, R. Kuiper, A. J. Walsh, K. G. Johnston and S. N. Longmore A&A, 621 (2019) A122 Published online: 16 January 2019 DOI: 10.1051/0004-6361/201834064