The first Hi-GAL observations of the outer Galaxy: a look to star
  formation in the third Galactic quadrant in the longitude range 216.5 < l <
  225.5
  We present the first Herschel PACS and SPIRE photometric observations in a
portion of the outer Galaxy ($216.5^{\circ} \lesssim \ell \lesssim
225.5^{\circ}$ and $-2^{\circ} \lesssim b \lesssim 0^{\circ}$) as a part of the
Hi-GAL survey. The maps between 70 and 500 $\mu$m, the derived column density
and temperature maps, and the compact source catalog are presented. NANTEN
CO(1-0) line observations are used to derive cloud kinematics and distances, so
that we can estimate distance-dependent physical parameters of the compact
sources (cores and clumps) having a reliable spectral energy distribution, that
we separate in 255 proto-stellar and 688 starless. Both typologies are found in
association with all the distance components observed in the field, up to $\sim
5.8$ kpc, testifying the presence of star formation beyond the Perseus arm at
these longitudes. Selecting the starless gravitationally bound sources we
identify 590 pre-stellar candidates. Several sources of both proto- and
pre-stellar nature are found to exceed the minimum requirement for being
compatible with massive star formation, based on the mass-radius relation. For
the pre-stellar sources belonging to the Local arm ($d\lesssim1.5$ kpc) we
study the mass function, whose high-mass end shows a power-law $N(\log M)
\propto M^{-1.0 \pm 0.2}$. Finally, we use a luminosity vs mass diagram to
infer the evolutionary status of the sources, finding that most of the
proto-stellar are in the early accretion phase (with some cases compatible with
a Class I stage), while for pre-stellar sources, in general, accretion has not
started yet.
