The Interstellar Medium of Young Stellar Clusters from the Mid-Infrared Point of View

Effects of young stellar clusters on their gas and dust environment are probed using mid-infrared (MIR) wavelengths. The strong MIR [NeIII]/[NeII] ratios (∼ 5 to 10) reveal the presence of current massive stars less than 5Myr. Using MIR line ratios along with optical and NIR data from the literature, composite SEDs are constructed for NGC 1569, NGC 1140 and II Zw40. The stellar SEDs are then used as input to a dust model to study the impact of the hard, penetrating radiation field on the dust components, particularly in low metallicity environments, where the destructive effects of the massive stellar clusters on the environments occur on global scales. For example, the smallest dust particles are destroyed over larger regions in the dwarf galaxies than in normal metallicity starbursts.