The M16 molecular complex under the influence of NGC6611. Herschel's
  perspective of the heating effect on the Eagle Nebula
  We present Herschel images from the HOBYS key program of the Eagle Nebula
(M16) in the far-infrared and sub-millimetre, using the PACS and SPIRE cameras
at 70{\mu}m, 160{\mu}m, 250{\mu}m, 350{\mu}m, 500{\mu}m. M16, home to the
Pillars of Creation, is largely under the influence of the nearby NGC6611
high-mass star cluster. The Herschel images reveal a clear dust temperature
gradient running away from the centre of the cavity carved by the OB cluster.
We investigate the heating effect of NGC6611 on the entire M16 star-forming
complex seen by Herschel including the diffuse cloud environment and the dense
filamentary structures identified in this region. In addition, we interpret the
three-dimensional geometry of M16 with respect to the nebula, its surrounding
environment, and the NGC6611 cavity. The dust temperature and column density
maps reveal a prominent eastern filament running north-south and away from the
high-mass star-forming central region and the NGC6611 cluster, as well as a
northern filament which extends around and away from the cluster. The dust
temperature in each of these filaments decreases with increasing distance from
the NGC6611 cluster, indicating a heating penetration depth of \sim 10 pc in
each direction in 3 - 6 \times 10^{22} cm-2 column density filaments. We show
that in high-mass star-forming regions OB clusters impact the temperature of
future star-forming sites, modifying the initial conditions for collapse and
effecting the evolutionary criteria of protostars developed from spectral
energy distributions. Possible scenarios for the origin of the morphology seen
in this region are discussed, including a western equivalent to the eastern
filament, which was destroyed by the creation of the OB cluster and its
subsequent winds and radiation.
