W 49 A North - Global or Local or No Collapse ?

We attempt to fit observations with 5 resolution of the J=2−1 transition of CS in the directions of H ii regions A, B, and G of W49A North as well as observations with 20 resolution of the J=2−1, 3−2, 5−4, and 7−6 transitions in the directions of H ii regions A and G by using radiative transfer calculations. These calculations predict the intensity profiles resulting from several spherical clouds along the line of sight. We consider three models: global collapse of a very large (5 pc radius) cloud, localized collapse from smaller (1 pc) clouds around individual H ii regions, and multiple, static clouds. For all three models we can find combinations of parameters that reproduce the CS profiles reasonably Department of Astronomy, University of Illinois, 103 Astronomy Building, 1002 West Green Street, Urbana, IL 61801