Herschel photometric observations of the nearby low metallicity
  irregular galaxy NGC 6822
  We present the first Herschel PACS and SPIRE images of the low-metallicity
galaxy NGC6822 observed from 70 to 500 mu and clearly resolve the HII regions
with PACS and SPIRE. We find that the ratio 250/500 is dependent on the 24 mu
surface brightness in NGC6822, which would locally link the heating processes
of the coldest phases of dust in the ISM to the star formation activity. We
model the SEDs of some regions HII regions and less active regions across the
galaxy and find that the SEDs of HII regions show warmer ranges of dust
temperatures. We derive very high dust masses when graphite is used in our
model to describe carbon dust. Using amorphous carbon, instead, requires less
dust mass to account for submm emission due to its lower emissivity properties.
This indicates that SED models including Herschel constraints may require
different dust properties than commonly used.
