Dynamical evolution of a dusty H II-region.

A previously described method is applied to a dusty model H II region in order to compute the evolution of hydrodynamical parameters, the evolution of the ionization structure of H and He, and the diffusion effect among all relevant components (H, He, dust). The space-time evolution of a spherical gas-dust cloud around a central star capable of ionizing the surrounding medium is considered for the case of a steady-state, homogeneous, and isotropic cold cloud consisting of H, He, and dust, and with a hot star formed at the center. The results obtained are shown to provide both a quantitative picture of the global hydrodynamical evolution of the H II region and a variety of effects giving detailed insight into the dynamical coupling of the different components and its relevance to local and global evolution.