Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spitzer Observations of Dust Emission from HII Regions in the Large
  Magellanic Cloud   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
(N63 and N180) and two simple superbubbles (N70 and N144) 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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The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
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The categories of this paper are: quant-ph