Joblin, C. and Lord, S. D. and Phillips, T. G. and Colin, B. (2010) Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023. Astronomy and Astrophysics, 521 . L25. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20101222-113251478
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Context. We investigate the physics and chemistry of the gas and dust in dense photon-dominated regions (PDRs), along with their dependence on the illuminating UV field. Aims. Using Herschel/HIFI observations, we study the gas energetics in NGC 7023 in relation to the morphology of this nebula. NGC 7023 is the prototype of a PDR illuminated by a B2V star and is one of the key targets of Herschel. Methods. Our approach consists in determining the energetics of the region by combining the information carried by the mid-IR spectrum (extinction by classical grains, emission from very small dust particles) with that of the main gas coolant lines. In this letter, we discuss more specifically the intensity and line profile of the 158 μm (1901 GHz) [C ii] line measured by HIFI and provide information on the emitting gas. Results. We show that both the [C ii] emission and the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) arise from the regions located in the transition zone between atomic and molecular gas. Using the Meudon PDR code and a simple transfer model, we find good agreement between the calculated and observed [C ii] intensities. Conclusions. HIFI observations of NGC 7023 provide the opportunity to constrain the energetics at the surface of PDRs. Future work will include analysis of the main coolant line [O i] and use of a new PDR model that includes PAH-related species.
|Additional Information:||© 2010 ESO. Received 1 June 2010; Accepted 19 July 2010; Published online 01 October 2010. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France, and the US. Consortium members are: Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland, NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri- INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronímico Nacional (IGN), Centro de Astrobiología (CSIC-INTA). Sweden: Chalmers University of Technology - MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University - Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. This work was supported by the German Deutsche Forschungsgemeinschaft, DFG project number Os 177/1–1. A portion of this research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space administration.|
|Subject Keywords:||ISM: structure; ISM: kinematics and dynamics; ISM: molecules; submillimeter: ISM|
|Official Citation:||Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023 C. Joblin, P. Pilleri, J. Montillaud, A. Fuente, M. Gerin, O. Berné, V. Ossenkopf, J. Le Bourlot, D. Teyssier, J. R. Goicoechea, F. Le Petit, M. Röllig, M. Akyilmaz, A. O. Benz, F. Boulanger, S. Bruderer, C. Dedes, K. France, R. Güsten, A. Harris, T. Klein, C. Kramer, S. D. Lord, P. G. Martin, J. Martin-Pintado, B. Mookerjea, Y. Okada, T. G. Phillips, J. R. Rizzo, R. Simon, J. Stutzki, F. van der Tak, H. W. Yorke, E. Steinmetz, C. Jarchow, P. Hartogh, C. E. Honingh, O. Siebertz, E. Caux and B. Colin A&A 521 L25 (2010) DOI: 10.1051/0004-6361/201015129|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||23 Dec 2010 16:19|
|Last Modified:||26 Dec 2012 12:47|
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