EDP Sciences
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Volume 402, Number 3, May II 2003
First Science with the ODIN satellite
Page(s) L47 - L54
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20030339

A&A 402, L47-L54 (2003)
DOI: 10.1051/0004-6361:20030339


Odin water mapping in the Orion KL region

A. O. H. Olofsson1, G. Olofsson2, Å. Hjalmarson1, P. Bergman1, J. H. Black1, R. S. Booth1, V. Buat3, C. L. Curry4, P. J. Encrenaz5, E. Falgarone6, P. Feldman7, M. Fich4, H. G. Florén2, U. Frisk8, M. Gerin6, E. M. Gregersen9, J. Harju10, T. Hasegawa11, L. E. B. Johansson1, S. Kwok11, B. Larsson2, A. Lecacheux12, T. Liljeström13, R. Liseau2, K. Mattila10, G. F. Mitchell14, H. L. Nordh15, M. Olberg1, H. Olofsson2, L. Pagani5, R. Plume11, I. Ristorcelli16, G. Rydbeck1, Aa. Sandqvist2, F. von Schéele8, G. Serra16, N. F. Tothill14, K. Volk11 and C. D. Wilson9

1  Onsala Space Observatory (OSO), 439 92 Onsala, Sweden
2  Stockholm Observatory, SCFAB, Roslagstullsbacken 21, 106 91 Stockholm, Sweden
3  Laboratoire d'Astronomie Spatiale, BP 8, 13376 Marseille Cedex 12, France
4  Department of Physics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
5  LERMA & FRE 2460 du CNRS, Observatoire de Paris, 61 Av. de l'Observatoire, 75140 Paris, France
6  LERMA & FRE 2460 du CNRS, École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
7  NRC-HIA, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
8  Swedish Space Corporation, PO Box 4207, 171 04 Solna, Sweden
9  Department of Physics and Astronomy, McMaster University, Hamilton, ON L8S 4M1, Canada
10  Observatory, PO Box 14, University of Helsinki, 00014 Helsinki, Finland
11  Department of Physics and Astronomy. University of Calgary, Calgary, ABT 2N 1N4, Canada
12  LESIA, Observatoire de Paris, Section de Meudon, 5 place Jules Janssen, 92195 Meudon Cedex, France
13  Metsähovi Radio Observatory, Helsinki University of Technology, Otakaari 5A, 02150 Espoo, Finland
14  Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3, Canada
15  Swedish National Space Board, Box 4006, 171 04 Solna, Sweden
16  CESR, 9 avenue du Colonel Roche, BP 4346, 31029 Toulouse, France

(Received 3 December 2002 / Accepted 14 February 2003)

New results from water mapping observations of the Orion KL region using the submm/mm wave satellite Odin (2.1´beam size at 557 GHz), are presented. The ortho-H 2O $J_{K_{+}K_{-}}\!=\!1_{1,0}\!\rightarrow\!1_{0,1}$ ground state transition was observed in a $7\arcmin\times 7\arcmin$ rectangular grid with a spacing of 1´, while the same line of H 218Owas measured in two positions, Orion KL itself and 2´ south of Orion KL. In the main water species, the KL molecular outflow is largely resolved from the ambient cloud and it is found to have an extension of 60´´-110´´. The H 2O outflow profile exhibits a rather striking absorption-like asymmetry at the line centre. Self-absorption in the near (or "blue") part of the outflow (and possibly in foreground quiescent halo gas) is tentatively suggested to play a role here. We argue that the dominant part of the KL H 218Ooutflow emission emanates from the compact (size ~15´´) low-velocity flow and here estimate an H 2Oabundance of circa 10 -5 compared to all H 2 in the flow - an order of magnitude below earlier estimates of the H 2O abundance in the shocked gas of the high-velocity flow. The narrow ambient cloud lines show weak velocity trends, both in the N-S and E-W directions. H 218Ois detected for the first time in the southern position at a level of ~0.15 K and we here estimate an H 2Oabundance of (1-8)  $\times
10^{-8}$ .

Key words: ISM: abundances -- ISM: individual objects: Orion KL -- ISM: molecules -- submillimeter

Offprint request: A. O. H. Olofsson, henrik@oso.chalmers.se

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