  We combine Spitzer and Herschel data of the star-forming region N11 in the
Large Magellanic Cloud to produce detailed maps of the dust properties in the
complex and study their variations with the ISM conditions. We also compare
APEX/LABOCA 870um observations with our model predictions in order to decompose
the 870um emission into dust and non-dust (free-free emission and CO(3-2) line)
contributions. We find that in N11, the 870um can be fully accounted for by
these 3 components. The dust surface density map of N11 is combined with HI and
CO observations to study local variations in the gas-to-dust mass ratios. Our
analysis leads to values lower than those expected from the LMC low-metallicity
as well as to a decrease of the gas-to-dust mass ratio with the dust surface
density. We explore potential hypotheses that could explain the low observed
gas-to-dust mass ratios (variations in the XCO factor, presence of CO-dark gas
or of optically thick HI or variations in the dust abundance in the dense
regions). We finally decompose the local SEDs using a Principal Component
Analysis (i.e. with no a priori assumption on the dust composition in the
complex). Our results lead to a promising decomposition of the local SEDs in
various dust components (hot, warm, cold) coherent with that expected for the
region. Further analysis on a larger sample of galaxies will follow in order to
understand how unique this decomposition is or how it evolves from one
environment to another.
