Letters to the Editor

Characterizing interstellar filaments with Herschel in IC 5146 ^⋆,⋆⋆

¹ Laboratoire AIM, CEA/DSM–CNRS–Université Paris Diderot, IRFU/Service d’Astrophysique, CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France
e-mail: doris.arzoumanian@cea.fr; pandre@cea.fr
² Institute d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis Boulevard Arago, 75014 Paris, France
³ Laboratoire d’Astrophysique de Marseille, CNRS/INSU-Université de Provence, 13388 Marseille Cedex 13, France
⁴ Université de Bordeaux, OASU, Bordeaux, France
⁵ National Research Council of Canada, Herzberg Institute of Astrophysics, University of Victoria, Department of Physics and Astronomy, Victoria, Canada
⁶ School of Physics & Astronomy, Cardiff University, Cardiff, UK
⁷ Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S 3H8, Canada
⁸ IFSI - INAF, via Fosso del Cavaliere 100, 00133 Roma, Italy
⁹ The Rutherford Appleton Laboratory, Chilton, Didcot OX11 0NL, UK
¹⁰ Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
¹¹ Department of Physics & Astronomy, The Open University, Milton Keynes, UK

Received: 27 January 2011
Accepted: 17 February 2011

Abstract

We provide a first look at the results of the Herschel Gould Belt survey toward the IC 5146 molecular cloud and present a preliminary analysis of the filamentary structure in this region. The column density map, derived from our 70–500 μm Herschel data, reveals a complex network of filaments and confirms that these filaments are the main birth sites of prestellar cores. We analyze the column density profiles of 27 filaments and show that the underlying radial density profiles fall off as r^-1.5 to r^-2.5 at large radii. Our main result is that the filaments seem to be characterized by a narrow distribution of widths with a median value of 0.10 ± 0.03 pc, which is in stark contrast to a much broader distribution of central Jeans lengths. This characteristic width of  ~0.1 pc corresponds to within a factor of  ~2 to the sonic scale below which interstellar turbulence becomes subsonic in diffuse gas, which supports the argument that the filaments may form as a result of the dissipation of large-scale turbulence.