HAL : hal-00495803, version 1

arXiv : 1005.4517

Code Bibliographique ADS : 2010arXiv1005.4517N

DOI : 10.1051/0004-6361/201014603

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Astronomy and Astrophysics 518 (2010) L120

Water cooling of shocks in protostellar outflows: Herschel-PACS map of L1157

B. Nisini 1, M. Benedettini, C. Codella, T. Giannini, R. Liseau, D. Neufeld, M. Tafalla, E. F. Van Dishoeck, R. Bachiller, O. A. Benz, E. Bergin, P. Bjerkeli, G. Blake 2, S. Bontemps 3, 4, 5, 6, J. Braine 3, 4, 5, 6, S. Bruderer, P. Caselli 7, 8, 9, J. Cernicharo 10, F. Daniel, P. Encrenaz 11, A. M. di Giorgio, C. Dominik 12, S. Doty, M. Fich, A. Fuente, J. R. Goicoechea 11, Th. de Graaw, F. Helmich, G. Herczeg, Fabrice Herpin 3, 4, 5, 6, M. Hogerheijde, T. Jacq 3, 4, 5, 6, D. Johnstone, J. Jorgensen 13, M. Kaufman, L. Kirstensen, B. Larsson, D. Lis, M. Marseille 3, 4, 5, 6, 14, C. McCoey, G. Melnick, M. Olberg 15, B. Parise 16, 17, J. Pearson, R. Plime, C. Risacher 18, J. Santiago, P. Saraceno 19, R. Shipman, T. A. van Kempen, R. Visser, S. Viti, S. Wampfler, F. Wyrowski 20, F. van der Tak, U. A. Yildiz, B. Delforge, J. Desbat, W. A. Hatch, I. Peron, R. Schieder, J. A. Stern, D. Teyssier 21, Alain Baudry 3, 4, 5, 6, N. Whyborn

(2010)

In the framework of the Water in Star-forming regions with Herschel (WISH) key program, maps in water lines of several outflows from young stars are being obtained, to study the water production in shocks and its role in the outflow cooling. This paper reports the first results of this program, presenting a PACS map of the o-H2O 179 um transition obtained toward the young outflow L1157. The 179 um map is compared with those of other important shock tracers, and with previous single-pointing ISO, SWAS, and Odin water observations of the same source that allow us to constrain the water abundance and total cooling. Strong H2O peaks are localized on both shocked emission knots and the central source position. The H2O 179 um emission is spatially correlated with emission from H2 rotational lines, excited in shocks leading to a significant enhancement of the water abundance. Water emission peaks along the outflow also correlate with peaks of other shock-produced molecular species, such as SiO and NH3. A strong H2O peak is also observed at the location of the proto-star, where none of the other molecules have significant emission. The absolute 179 um intensity and its intensity ratio to the H2O 557 GHz line previously observed with Odin/SWAS indicate that the water emission originates in warm compact clumps, spatially unresolved by PACS, having a H2O abundance of the order of 10^-4. This testifies that the clumps have been heated for a time long enough to allow the conversion of almost all the available gas-phase oxygen into water. The total water cooling is ~10^-1 Lo, about 40% of the cooling due to H2 and 23% of the total energy released in shocks along the L1157 outflow.

1 :	Osservatorio di Astrofisica di Roma (OAR)
	INAF
2 :	Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE)
	Université de Savoie – CNRS : FRE3220
3 :	Observatoire aquitain des sciences de l'univers (OASU)
	CNRS : UMS2567 – INSU – Université Sciences et Technologies - Bordeaux I
4 :	Laboratoire d'Astrophysique de Bordeaux (LAB)
	CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
5 :	Université Sciences et Technologies - Bordeaux 1
	Université Sciences et Technologies - Bordeaux I
6 :	Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB)
	CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
7 :	Osservatorio Astrofisico di Arcetri (INAF)
	Osservatorio Astrofisico di Arcetri
8 :	Osservatorio di arcetri (INAF)
	INFN
9 :	Osservatorio Astrofisico di Arcetri (INAF)
	INFN
10 :	Centro de Investigaciones Biológicas (CSIC)
	Consejo Superior de Investigaciones Cientificas
11 :	Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA)
	CNRS : UMR8112 – INSU – Observatoire de Paris – Université Pierre et Marie Curie (UPMC) - Paris VI – Université de Cergy Pontoise – Ecole normale supérieure de Paris - ENS Paris
12 :	Astronomical Institute "Anton Pannekoek''
	University of Amsterdam
13 :	Leiden Observatory (Leiden Observatory)
	Leiden University
14 :	Institute for Space Research Netherlands (SRON)
	SRON Netherlands Institute for Space Research
15 :	Onsala Space Observatory
	Onsala Space Observatory
16 :	Centre d'étude spatiale des rayonnements (CESR)
	CNRS : UMR5187 – Observatoire Midi-Pyrénées – INSU – Université Paul Sabatier [UPS] - Toulouse III
17 :	Centre d'Etude Spatiale des Rayonnements
	Aucune
18 :	ESO
	ESO
19 :	Interplanetary Space Physics Institute (IFSI) (IFSI-INAF)
	Interplanetary Space Physics Institute
20 :	Max-Planck-Institut für Radioastronomie (MPIFR)
	Max-Planck-Institut
21 :	Herschel Science Center
	ESA

Domaine

:

Physique/Astrophysique/Astrophysique stellaire et solaire Planète et Univers/Astrophysique/Astrophysique stellaire et solaire

Mots Clés : Astrophysics - Galaxy Astrophysics – Astrophysics - Solar and Stellar Astrophysics

hal-00495803, version 1

http://hal.archives-ouvertes.fr/hal-00495803

oai:hal.archives-ouvertes.fr:hal-00495803

Contributeur : Marie-Paule Pomies <>

Soumis le : Mardi 29 Juin 2010, 08:56:19

Dernière modification le : Lundi 27 Septembre 2010, 15:01:28