Mid-and far-infrared studies of galactic compact H II regions

Abstract

Several Galactic H II region complexes have been observed in the far infrared (FIR) wavebands using the TIFR 1-m balloon borne telescope, and in the mid infrared (MIR) using the Infrared Space Observatory (ISO). Many of these FIR maps show interesting structural details. The MIR observations have clearly detected PAH features in two compact H II regions and one molecular clump. A self consistent radiative transfer scheme (1-D) has been developed which has been successful in extracting important details like geometric sizes, radial density distribution, dust composition, etc, from these and other similar measurements. A new scheme (2-D) has been developed in cylindrical geometry to model IRAS 19181 + 1349, which has been resolved into two sources. The model parameters in this scheme have been constrained by the observed spectral energy distribution (SED) and radial profiles at MIR & FIR wavebands. Non-equilibrium processes have also been incorporated in spherical geometry, to explain the PAH emission features. This scheme has successfully explained high resolution spectra (ISO-SWS) of several Galactic compact H II regions.