Detection of a large fraction of atomic gas not associated with star-forming material in M17 SW J. P. Pérez-Beaupuits, J. Stutzki, V. Ossenkopf, M. Spaans, R. Güsten and H. Wiesemeyer A&A, 575 (2015) A9 Published online: 11 February 2015 DOI: 10.1051/0004-6361/201425020