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Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between H II regions and molecular clouds. The physical conditions within these regions show variations on very short spatial scales, and therefore PDRs constitute ideal laboratories for investigating the properties and evolution of dust grains. We have mapped IC 63 at high resolution from the UV to the NIR (275 nm to 1.6 $mu$m), using the Hubble Space Telescope WFC3. Using a Bayesian SED fitting tool, we simultaneously derive a set of stellar ($T_text{eff}$, $log(g)$, distance) and extinction ($A_V$, $R_V$) parameters for 520 background stars. We present maps of $A_V$ and $R_V$ with a resolution of 25 arcsec based on these results. The extinction properties vary across the PDR, with values for $A_V$ between 0.5 and 1.4 mag, and a decreasing trend in $R_V$, going from 3.7 at the front of the nebula to values as low as 2.5 further in. This provides evidence for evolution of the dust optical properties. We fit two modified blackbodies to the MIR and FIR SED, obtained by combining the $A_V$ map with data from Spitzer and Herschel. We derive effective temperatures (30 K and 227 K) and the ratio of opacities at 160 $mu$m to V band $kappa_{160} / kappa_V$ ($7.0 times 10^{-4}$ and $2.9 times 10^{-9}$) for the two dust populations. Similar fits to individual pixels show spatial variations of $kappa_{160} / kappa_{V}$. The analysis of our HST data, combined with these Spitzer and Herschel data, provides the first panchromatic view of dust within a PDR.
Optical and infrared continuum polarization from the interstellar medium is driven by radiative processes aligning the grains with the magnetic field. While a quantitative, predictive theory of Radiative Alignment Torques (RAT) exists and has been ex
Interstellar dust grain alignment causes polarization from UV to mm wavelengths, allowing the study of the geometry and strength of the magnetic field. Over last couple of decades observations and theory have led to the establishment of the Radiative
Bright-rimmed clouds (BRCs) are formed at the periphery of H$~$II regions as the radiation from the central star interacts with dense gas. The ionization and resulting compression of the clouds may lead to cloud disruption causing secondary star form
We map the dust distribution in the central 180 (~680 pc) region of the M31 bulge, based on HST/WFC3 and ACS observations in ten bands from near-ultraviolet (2700 A) to near-infrared (1.5 micron). This large wavelength coverage gives us great leverag
The dust emissivity spectral index, $beta$, is a critical parameter for deriving the mass and temperature of star-forming structures, and consequently their gravitational stability. The $beta$ value is dependent on various dust grain properties, such