Dust Properties of Massive Star Forming Regions

We present our dust property studies of massive star forming regions by investigating the opacity and emissivity variation within the areas of Galactic infrared dark clouds (IRDCs). Due to their extreme environments (e.g. Av ~ 50mag and higher), the detailed dust property studies toward massive star forming regions have not been successfully delivered to astronomy community even for last two decades of high angular resolution observations along MIR to sub-mm regime. Here we provide the first combined maps of dust opacity and emissivity across MIR, FIR, and sub-mm wavelength regime by utilizing Spitzer, WISE, and Herschel data (3.6 to 500 micron). In this study, the MIR and FIR (3.6 to 110 micron) extinction maps are constructed to derive the normalized opacity trends that are compared to the spectral index variation of the corresponding regions. Various dust models assuming dust grain size distribution, ice mantle, chemical composition, and grain growth via accretion / coagulation are compared to the derived opacity and emissivity trends. We discuss the detailed implication and potential application to future observations via JWST and other great facilities.