Dust Spectral Energy Distributions of Nearby Galaxies: an Insight from
  the Herschel Reference Survey
  We gather infrared (IR) photometric data from 8 to 500 microns (Spitzer,
WISE, IRAS and Herschel) for all of the HRS galaxies. Draine & Li (2007) models
are fit to the data from which the stellar contribution has been carefully
removed. We find that our photometric coverage is sufficient to constrain all
of the models parameters and that a strong constraint on the 20-60 microns
range is mandatory to estimate the relative contribution of the
photo-dissociation regions to the IR SED. The SED models tend to systematically
under-estimate the observed 500 microns flux densities, especially for low mass
systems. We provide the output parameters for all of the galaxies: the minimum
intensity of the interstellar radiation field (ISRF), the fraction of PAH, the
relative contribution of PDR and evolved stellar population to the dust
heating, the $M_{dust}$ and the $L_{IR}$. For a subsample of gas-rich galaxies,
we analyze the relations between these parameters and the integrated properties
of galaxies, such as $M_*$, SFR, metallicity, H$\alpha$ and H-band surface
brightness, and the FUV attenuation. A good correlation between the fraction of
PAH and the metallicity is found implying a weakening of the PAH emission in
galaxies with low metallicities. The intensity of the IRSF and the H-band and
H$\alpha$ surface brightnesses are correlated, suggesting that the diffuse dust
component is heated by both the young stars in star forming regions and the
diffuse evolved population. We use these results to provide a new set of IR
templates calibrated with Herschel observations on nearby galaxies and a mean
SED template to provide the z=0 reference for cosmological studies. For the
same purpose, we put our sample on the SFR-$M_*$ diagram. The templates are
compared to the most popular IR SED libraries, enlightening a large discrepancy
between all of them in the 20-100 microns range.
