Gravity as main driver of non-thermal motions in massive star forming regions A. Traficante, G.A. Fuller, R. Smith, N. Billot, A. Duarte-Cabral, N. Peretto, S. Molinari and J.E. Pineda EAS Publications Series, 75-76 (2015) 185-188 Published online: 20 May 2016 DOI: 10.1051/eas/1575034