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The CHESS spectral survey of star forming regions: Peering into the protostellar shock L1157-B1 - II. Shock dynamics

Lefloch, B. and Boogert, A. and Bell, T. and Blake, G. and Lis, D. and Lord, S. and Phillips, T. G. and Borys, C. (2010) The CHESS spectral survey of star forming regions: Peering into the protostellar shock L1157-B1 - II. Shock dynamics. Astronomy and Astrophysics, 518 . L113. ISSN 0004-6361. doi:10.1051/0004-6361/201014630.

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Context. The outflow driven by the low-mass class 0 protostar L1157 is the prototype of the so-called chemically active outflows. The bright bowshock B1 in the southern outflow lobe is a privileged testbed of magneto-hydrodynamical (MHD) shock models, for which dynamical and chemical processes are strongly interdependent. Aims. We present the first results of the unbiased spectral survey of the L1157-B1 bowshock, obtained in the framework of the key program “Chemical HErschel Surveys of star forming regions” (CHESS). The main aim is to trace the warm and chemically enriched gas and to infer the excitation conditions in the shock region. Methods. The CO 5-4 and o-H2_O 1_(10)–1_(01) lines have been detected at high-spectral resolution in the unbiased spectral survey of the HIFI-band 1b spectral window (555–636 GHz), presented by Codella et al. in this volume. Complementary ground-based observations in the submm window help establish the origin of the emission detected in the main-beam of HIFI and the physical conditions in the shock. Results. Both lines exhibit broad wings, which extend to velocities much higher than reported up to now. We find that the molecular emission arises from two regions with distinct physical conditions : an extended, warm (100 K), dense (3 × 10^5 cm^(-3)) component at low-velocity, which dominates the water line flux in Band 1; a secondary component in a small region of B1 (a few arcsec) associated with high-velocity, hot (>400 K) gas of moderate density ((1.0–3.0) × 10^4 cm^(-3)), which appears to dominate the flux of the water line at 179μm observed with PACS. The water abundance is enhanced by two orders of magnitude between the low- and the high-velocity component, from 8 × 10^(-7) up to 8 × 10^(-5). The properties of the high-velocity component agree well with the predictions of steady-state C-shock models.

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Blake, G.0000-0003-0787-1610
Lis, D.0000-0002-0500-4700
Additional Information:© 2010 ESO. Received 31 March 2010; Accepted 30 April 2010; Published online 16 July 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 Astronómico 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. HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS and SPIRE consortia.
Subject Keywords:stars: formation; ISM: jets and outflows; ISM: individual objects: L1157
Record Number:CaltechAUTHORS:20101119-104201063
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Official Citation:The CHESS spectral survey of star forming regions: Peering into the protostellar shock L1157-B1 - II. Shock dynamics B. Lefloch, S. Cabrit, C. Codella, G. Melnick, J. Cernicharo, E. Caux, M. Benedettini, A. Boogert, P. Caselli, C. Ceccarelli, F. Gueth, P. Hily-Blant, A. Lorenzani, D. Neufeld, B. Nisini, S. Pacheco, L. Pagani, J. R. Pardo, B. Parise, M. Salez, K. Schuster, S. Viti, A. Bacmann, A. Baudry, T. Bell, E. A. Bergin, G. Blake, S. Bottinelli, A. Castets, C. Comito, A. Coutens, N. Crimier, C. Dominik, K. Demyk, P. Encrenaz, E. Falgarone, A. Fuente, M. Gerin, P. Goldsmith, F. Helmich, P. Hennebelle, T. Henning, E. Herbst, T. Jacq, C. Kahane, M. Kama, A. Klotz, W. Langer, D. Lis, S. Lord, S. Maret, J. Pearson, T. Phillips, P. Saraceno, P. Schilke, X. Tielens, F. van der Tak, M. van der Wiel, C. Vastel, V. Wakelam, A. Walters, F. Wyrowski, H. Yorke, R. Bachiller, C. Borys, G. De Lange, Y. Delorme, C. Kramer, B. Larsson, R. Lai, F. W. Maiwald, J. Martin-Pintado, I. Mehdi, V. Ossenkopf, P. Siegel, J. Stutzki and J. H. Wunsch A&A 518 L113 (2010) DOI: 10.1051/0004-6361/201014630
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20913
Deposited On:22 Nov 2010 16:37
Last Modified:09 Nov 2021 00:04

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