Kristensen, L. E. and Blake, G. A. and Lis, D. (2010) Water in low-mass star-forming regions with Herschel: HIFI spectroscopy of NGC 1333. Astronomy and Astrophysics, 521 . L30. ISSN 0004-6361 http://resolver.caltech.edu/CaltechAUTHORS:20110107-141421734
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“Water In Star-forming regions with Herschel” (WISH) is a key programme dedicated to studying the role of water and related species during the star-formation process and constraining the physical and chemical properties of young stellar objects. The Heterodyne Instrument for the Far-Infrared (HIFI) on the Herschel Space Observatory observed three deeply embedded protostars in the low-mass star-forming region NGC 1333 in several H_(2)^(16)O, H_(2)^(18)O, and CO transitions. Line profiles are resolved for five H_(2)^(16)O transitions in each source, revealing them to be surprisingly complex. The line profiles are decomposed into broad (>20 km s^(-1)), medium-broad (~5-10 km s^(-1)), and narrow (<5 km s^(-1)) components. The H_(2)^(18)O emission is only detected in broad 1_(10)–1_(01) lines (>20 km s^(-1)), indicating that its physical origin is the same as for the broad H_(2)^(16)O component. In one of the sources, IRAS4A, an inverse P Cygni profile is observed, a clear sign of infall in the envelope. From the line profiles alone, it is clear that the bulk of emission arises from shocks, both on small (≲1000 AU) and large scales along the outflow cavity walls (~10 000 AU). The H2O line profiles are compared to CO line profiles to constrain the H_(2)O abundance as a function of velocity within these shocked regions. The H_(2)O/CO abundance ratios are measured to be in the range of ~0.1-1, corresponding to H2O abundances of ~10^(-5)–10^(-4) with respect to H_2. Approximately 5–10% of the gas is hot enough for all oxygen to be driven into water in warm post-shock gas, mostly at high velocities.
|Additional Information:||© 2010 ESO. Received 31 May 2010; Accepted 13 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. This work is made possible thanks to the HIFI guaranteed time programme. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada and the US under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands 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, Arcetri-INAF; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronomico 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 Zürich, 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. We thank many funding agencies for financial support.|
|Subject Keywords:||astrochemistry; stars: formation; ISM: molecules; ISM: jets and outflows; ISM: individual objects: NGC 1333|
|Official Citation:||Water in low-mass star-forming regions with Herschel - HIFI spectroscopy of NGC 1333 L. E. Kristensen, R. Visser, E. F. van Dishoeck, U. A. Yıldız, S. D. Doty, G. J. Herczeg, F.-C. Liu, B. Parise, J. K. Jørgensen, T. A. van Kempen, C. Brinch, S. F. Wampfler, S. Bruderer, A. O. Benz, M. R. Hogerheijde, E. Deul, R. Bachiller, A. Baudry, M. Benedettini, E. A. Bergin, P. Bjerkeli, G. A. Blake, S. Bontemps, J. Braine, P. Caselli, J. Cernicharo, C. Codella, F. Daniel, Th. de Graauw, A. M. di Giorgio, C. Dominik, P. Encrenaz, M. Fich, A. Fuente, T. Giannini, J. R. Goicoechea, F. Helmich, F. Herpin, T. Jacq, D. Johnstone, M. J. Kaufman, B. Larsson, D. Lis, R. Liseau, M. Marseille, C. McCoey, G. Melnick, D. Neufeld, B. Nisini, M. Olberg, J. C. Pearson, R. Plume, C. Risacher, J. Santiago-García, P. Saraceno, R. Shipman, M. Tafalla, A. G. G. M. Tielens, F. van der Tak, F. Wyrowski, D. Beintema, A. de Jonge, P. Dieleman, V. Ossenkopf, P. Roelfsema, J. Stutzki and N. Whyborn A&A 521 L30 (2010) DOI: 10.1051/0004-6361/201015100|
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|Deposited By:||Jason Perez|
|Deposited On:||11 Jan 2011 22:11|
|Last Modified:||26 Dec 2012 12:49|
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