HAL : hal-00495835, version 1

arXiv : 1005.2031

Code Bibliographique ADS : 2010A&A...518L.121V

DOI : 10.1051/0004-6361/201014615

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Astronomy and Astrophysics 518 (2010) L121

Origin of the hot gas in low-mass protostars: Herschel-PACS spectroscopy of HH 46

T. A. van Kempen, L. E. Kristensen, G. J. Herczeg, R. Visser, E. F. Van Dishoeck, S. F. Wampfler, S. Bruderer, A. O. Benz, S. D. Doty, C. Brinch, M. R. Hogerheijde, J. K. Jørgensen, M. Tafalla, D. Neufeld, R. Bachiller, Alain Baudry 1, 2, 3, 4, M. Benedettini, E. A. Bergin 5, P. Bjerkeli, G. A. Blake 6, S. Bontemps 1, 2, 3, 4, J. Braine 1, 2, 3, 4, P. Caselli 7, 8, 9, J. Cernicharo 10, C. Codella, F. Daniel, A. M. di Giorgio, C. Dominik 11, P. Encrenaz 12, M. Fich, A. Fuente, T. Giannini, J. R. Goicoechea 12, Th. de Graauw, F. Helmich, Fabrice Herpin 1, 2, 3, 4, T. Jacq 1, 2, 3, 4, D. Johnstone, M. J. Kaufman, B. Larsson, D. Lis, R. Liseau, M. Marseille 1, 2, 3, 4, 13, C. McCoey, G. Melnick, B. Nisini 14, M. Olberg 15, B. Parise 16, 17, J. C. Pearson, R. Plume, C. Risacher 18, J. Santiago-Garcia, P. Saraceno 19, R. Shipman, F. van der Tak, F. Wyrowski 20, U. A. Yildiz, M. Ciechanowicz, L. Dubbeldam, S. Glenz, R. Huisman, R. H. Lin, P. Morris, J. A. Murphy, N. Trappe

(2010)

'Water in Star-forming regions with Herschel' (WISH) is a Herschel Key Programme aimed at understanding the physical and chemical structure of young stellar objects (YSOs) with a focus on water and related species. The low-mass protostar HH 46 was observed with the Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory to measure emission in H2O, CO, OH, [OI], and [CII] lines located between 63 and 186 um. The excitation and spatial distribution of emission can disentangle the different heating mechanisms of YSOs, with better spatial resolution and sensitivity than previously possible. Far-IR line emission is detected at the position of the protostar and along the outflow axis. The OH emission is concentrated at the central position, CO emission is bright at the central position and along the outflow, and H2O emission is concentrated in the outflow. In addition, [OI] emission is seen in low-velocity gas, assumed to be related to the envelope, and is also seen shifted up to 170 km/s in both the red- and blue-shifted jets. Envelope models are constructed based on previous observational constraints. They indicate that passive heating of a spherical envelope by the protostellar luminosity cannot explain the high-excitation molecular gas detected with PACS, including CO lines with upper levels at >2500 K above the ground state. Instead, warm CO and H2O emission is probably produced in the walls of an outflow-carved cavity in the envelope, which are heated by UV photons and non-dissociative C-type shocks. The bright OH and [OI] emission is attributed to J-type shocks in dense gas close to the protostar. In the scenario described here, the combined cooling by far-IR lines within the central spatial pixel is estimated to be 2 \times 10-2 L_sun, with 60-80% attributed to J- and C-type shocks produced by interactions between the jet and the envelope.

1 :	Observatoire aquitain des sciences de l'univers (OASU)
	CNRS : UMS2567 – INSU – Université Sciences et Technologies - Bordeaux I
2 :	Laboratoire d'Astrophysique de Bordeaux (LAB)
	CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
3 :	Université Sciences et Technologies - Bordeaux 1
	Université Sciences et Technologies - Bordeaux I
4 :	Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB)
	CNRS : UMR5804 – INSU – Université Sciences et Technologies - Bordeaux I
5 :	Harvard-Smithsonian Center for Astrophysics
	Harvard-Smithsonian Center for Astrophysics
6 :	Laboratoire Optimisation de la Conception et Ingénierie de l'Environnement (LOCIE)
	Université de Savoie – CNRS : FRE3220
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 :	Astronomical Institute "Anton Pannekoek''
	University of Amsterdam
12 :	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
13 :	Institute for Space Research Netherlands (SRON)
	SRON Netherlands Institute for Space Research
14 :	Osservatorio di Astrofisica di Roma (OAR)
	INAF
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

Domaine

:

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

Mots Clés : Astrophysics - Solar and Stellar Astrophysics

hal-00495835, version 1

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Contributeur : Marie-Paule Pomies <>

Soumis le : Mardi 29 Juin 2010, 09:26:26

Dernière modification le : Mercredi 29 Septembre 2010, 12:51:48