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Herschel/HIFI detections of hydrides towards AFGL 2591: Envelope emission versus tenuous cloud absorption

Bruderer, S. and Blake, G. A. and Lis, D. (2010) Herschel/HIFI detections of hydrides towards AFGL 2591: Envelope emission versus tenuous cloud absorption. Astronomy and Astrophysics, 521 . Art. No. L44. ISSN 0004-6361.

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The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory allows the first observations of light diatomic molecules at high spectral resolution and in multiple transitions. Here, we report deep integrations using HIFI in different lines of hydrides towards the high-mass star forming region AFGL 2591. Detected are CH, CH^+, NH, OH^+, H_2O^+, while NH^+ and SH^+ have not been detected. All molecules except for CH and CH^+ are seen in absorption with low excitation temperatures and at velocities different from the systemic velocity of the protostellar envelope. Surprisingly, the CH(J_(F,P) = 3/2_(2,−) − 1/2_(1,+)) and CH^+(J = 1−0, J = 2−1) lines are detected in emission at the systemic velocity. We can assign the absorption features to a foreground cloud and an outflow lobe, while the CH and CH^+ emission stems from the envelope. The observed abundance and excitation of CH and CH^+ can be explained in the scenario of FUV irradiated outflow walls, where a cavity etched out by the outflow allows protostellar FUV photons to irradiate and heat the envelope at larger distances driving the chemical reactions that produce these molecules.

Item Type:Article
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Blake, G. A.0000-0003-0787-1610
Lis, D.0000-0002-0500-4700
Additional Information:© 2010 ESO. Received 31 May 2010, Accepted 20 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. Apppendices and Table 1 (pages 6 to 7) are only available in electronic form at We thank the anonymous referee for useful comments. The work on star formation at ETH Zurich is partially funded by the Swiss National Science Foundation grant 200020-113556. This program is made possible thanks to the Swiss HIFI guaranteed time program. 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 Astrobiologá (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.
Funding AgencyGrant Number
Swiss National Science Foundation (SNSF)200020-113556
Subject Keywords:ISM: molecules – stars: formation – astrochemistry – ISM: individual objects: AFGL 2591
Record Number:CaltechAUTHORS:20101221-104620418
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Official Citation:Herschel/HIFI detections of hydrides towards AFGL 2591 - Envelope emission versus tenuous cloud absorption S. Bruderer, A. O. Benz, E. F. van Dishoeck, M. Melchior, S. D. Doty, F. van der Tak, P. Stäuber, S. F. Wampfler, C. Dedes, U. A. Yıldız, L. Pagani, T. Giannini, Th. de Graauw, N. Whyborn, D. Teyssier, W. Jellema, R. Shipman, R. Schieder, N. Honingh, E. Caux, W. Bächtold, A. Csillaghy, C. Monstein, R. Bachiller, A. Baudry, M. Benedettini, E. Bergin, P. Bjerkeli, G. A. Blake, S. Bontemps, J. Braine, P. Caselli, J. Cernicharo, C. Codella, F. Daniel, A. M. di Giorgio, C. Dominik, P. Encrenaz, M. Fich, A. Fuente, J. R. Goicoechea, F. Helmich, G. J. Herczeg, F. Herpin, M. R. Hogerheijde, T. Jacq, D. Johnstone, J. K. Jørgensen, L. E. Kristensen, B. Larsson, D. Lis, R. Liseau, M. Marseille, C. McCoey, G. Melnick, D. Neufeld, B. Nisini, M. Olberg, B. Parise, J. C. Pearson, R. Plume, C. Risacher, J. Santiago-García, P. Saraceno, R. Shipman, M. Tafalla, T. A. van Kempen, R. Visser and F. Wyrowski A&A 521 L44 (2010) DOI: 10.1051/0004-6361/201015098
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21479
Deposited By: Benjamin Perez
Deposited On:21 Dec 2010 19:24
Last Modified:03 Oct 2019 02:25

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