On the nature of dust clouds in the region towards M81 and NGC3077
  There is some controversy on the nature of dust clouds found in direction of
the interacting galaxy triplett M81, M82, and NGC3077. Are they associated with
the tidal arms seen in HI around those galaxies or are they simply Galactic
foreground clouds? Data from the SPIRE instrument onboard HERSCHEL and MIPS
onboard of SPITZER are used to derive physical parameters for the dust clouds.
These observions are compared to CO clouds previously mapped with the IRAM and
the FCRAO radio telescopes.SPIRE and MIPS maps show several dust clouds north
of M81 and south of NGC3077. Modelling of the dust emission provides total
hydrogen column densities between 1.5 and 5.0 * 10^20 cm^-2. Dust temperatures
are between 13 to 17K. No significant difference in the dust emission can be
found between individual clouds. It is shown that CO line emission provides the
best clues on the origin of those clouds. Most of the clouds seen towards M81
are associated with small-area molecular structures (SAMS), i.e. tiny CO clouds
of Galactic origin. The clouds seen towards NGC3077 are partly associated with
the tidal arms and are partly in the Galactic foreground associated with SAMS.
