The M 16 molecular complex under the influence of NGC 6611

Herschel’s perspective of the heating effect on the Eagle Nebula^⋆,⋆⋆

¹ Laboratoire AIM, CEA/IRFU CNRS/INSU Université Paris Diderot, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: tracey.hill@cea.fr
² The Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0NL, UK
³ Department of Physics and Astronomy, The Open University, Milton Keynes, UK
⁴ Herschel Science Centre, ESAC, Spain
⁵ Université de Bordeaux, OASU, Bordeaux, France
⁶ National Research Council of Canada, 5071 West Saanich Road, Victoria, BC, V9E 2E7, Canada
⁷ Department of Physics, West Virginia University, Morgantown, WV 26506, USA
⁸ Université de Toulouse, UPS, CESR, 9 avenue du Colonel Roche, CNRS, UMR 5187, 31028 Toulouse Cedex 4, France
⁹ IAPS – Instituto di Astrofisica e Planetologia Spaziali, via Fosso del Cavaliere 100, 00133 Roma, Italy
¹⁰ School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF243 AA, UK
¹¹ National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012, PR China
¹² Institut d’Astrophysique de Paris, Université Pierre et Marie Curie (UPMC), CNRS (UMR 7095), 75014 Paris, France
¹³ ESO, Karl Schwarzschild str. 2, 85748 Garching bei Munchen, Germany
¹⁴ Jeremiah Horrocks Institute, University of Central Lancashire, PR1 2HE, UK
¹⁵ Laboratoire d’Astrophysique de Marseille UMR 6110, CNRS, Université de Provence, 38 rue F. Joliot-Curie, 13388 Marseille, France

Received: 10 February 2012
Accepted: 26 April 2012

Abstract

We present Herschel images from the HOBYS key program of the Eagle Nebula (M 16) in the far-infrared and sub-millimetre, using the PACS and SPIRE cameras at 70 μm, 160 μm, 250 μm, 350 μm, 500 μm. M 16, home to the Pillars of Creation, is largely under the influence of the nearby NGC 6611 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 NGC 6611 on the entire M 16 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 M 16 with respect to the nebula, its surrounding environment, and the NGC 6611 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 NGC 6611 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 NGC 6611 cluster, indicating a heating penetration depth of  ~10 pc in each direction in 3–6  ×  10²² 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 initialconditions 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.