Abstract
Massive stars can alter physical conditions and properties of their ambient
interstellar dust grains via radiative heating and shocks. The HII regions in
the Large Magellanic Cloud (LMC) offer ideal sites to study the stellar energy
feedback effects on dust because stars can be resolved, and the galaxy's nearly
face-on orientation allows us to unambiguously associate HII regions with their
ionizing massive stars. The Spitzer Space Telescope survey of the LMC provides
multi-wavelength (3.6 to 160 $\mu$m) photometric data of all HII regions. To
investigate the evolution of dust properties around massive stars, we have
analyzed spatially-resolved IR dust emission from two classical HII regions and
two simple superbubbles in the LMC. We produce photometric spectral energy
distributions (SEDs) of numerous small subregions for each region based on its
stellar distributions and nebular morphologies. We use DustEM dust emission
model fits to characterize the dust properties. Color-color diagrams and model
fits are compared with the radiation field (estimated from photometric and
spectroscopic surveys). Strong radial variations of SEDs can be seen throughout
the regions, reflecting the available radiative heating. Emission from very
small grains drastically increases at locations where the radiation field is
the highest, while polycyclic aromatic hydrocarbons (PAHs) appear to be
destroyed. PAH emission is the strongest in the presence of molecular clouds,
provided that the radiation field is low.
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