Models of wave supported clumps in giant molecular clouds

We present plane-parallel equilibrium models of molecular clumps that are s upported by Alfven waves damped by the linear process of ion-neutral fricti on. We used a WKB approximation to treat the inward propagation of waves an d adopted a realistic ionization structure influenced by dissociation and i onization due to photons of external origin. The model clumps contain centr al condensations surrounded by lower density envelopes and are more condens ed than those obtained for an assumed ionization structure, used in some pr evious studies, that is more appropriate for dark regions. In some paramete r regimes the structures of clumps depend sensitively on the assumed deplet ions of Sulphur and metals.