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Cernicharo J, Teyssier D, Quintana-Lacaci G, Daniel F, Agúndez M, Prieto LV, Decin L, Guélin M, Encrenaz P, García-Lario P, de Beck E, Barlow MJ, Groenewegen MAT, Neufeld D, Pearson J. Discovery of Time Variation of the Intensity of Molecular Lines in IRC+10216 in The Submillimeter and Far Infrared Domains. Astrophys J Lett 2014; 796:L21. [PMID: 26722620 PMCID: PMC4693957 DOI: 10.1088/2041-8205/796/1/l21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report on the discovery of strong intensity variations in the high rotational lines of abundant molecular species towards the archetypical circumstellar envelope of IRC+10216. The observations have been carried out with the HIFI instrument on board Herschel and with the IRAM 30-m telescope. They cover several observing periods spreading over 3 years. The line intensity variations for molecules produced in the external layers of the envelope most probably result from time variations in the infrared pumping rates. We analyze the main implications this discovery has on the interpretation of molecular line emission in the envelopes of Mira-type stars. Radiative transfer calculations have to take into account both the time variability of infrared pumping and the possible variation of the dust and gas temperatures with stellar phase in order to reproduce the observation of molecular lines at different epochs. The effect of gas temperature variations with stellar phase could be particularly important for lines produced in the innermost regions of the envelope. Each layer of the circumstellar envelope sees the stellar light radiation with a different lag time (phase). Our results show that this effect must be included in the models. The sub-mm and FIR lines of AGB stars cannot anymore be considered as safe intensity calibrators.
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Affiliation(s)
- J Cernicharo
- Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain
| | - D Teyssier
- ESA. ESAC. P.O. Box 78, Villanueva de la Cañada E-28691 Madrid. Spain
| | - G Quintana-Lacaci
- Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain
| | - F Daniel
- Univ. Grenoble Alpes, IPAG, F-38000 Grenoble, France CNRS, IPAG, F-38000 Grenoble, France
| | - M Agúndez
- Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain
| | - L Velilla Prieto
- Group of Molecular Astrophysics. ICMM. CSIC. C/Sor Juana Inés de La Cruz N3. E-28049, Madrid. Spain
| | - L Decin
- Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium
| | - M Guélin
- Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406, St-Martin d'Hères, France
| | - P Encrenaz
- LERMA, Observatoire de Paris, 61 Av. de l'Observatoire, F-75014 Paris, France
| | - P García-Lario
- ESA. ESAC. P.O. Box 78, Villanueva de la Cañada E-28691 Madrid. Spain
| | - E de Beck
- Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE 43992 Onsala, Sweden
| | - M J Barlow
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
| | - M A T Groenewegen
- Koninklijke Sterrenwacht van België, Ringlaan 3, B-1180, Brussel, Belgium
| | - D Neufeld
- Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - J Pearson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 91109, USA
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Decin L, Agúndez M, Barlow MJ, Daniel F, Cernicharo J, Lombaert R, De Beck E, Royer P, Vandenbussche B, Wesson R, Polehampton ET, Blommaert JADL, De Meester W, Exter K, Feuchtgruber H, Gear WK, Gomez HL, Groenewegen MAT, Guélin M, Hargrave PC, Huygen R, Imhof P, Ivison RJ, Jean C, Kahane C, Kerschbaum F, Leeks SJ, Lim T, Matsuura M, Olofsson G, Posch T, Regibo S, Savini G, Sibthorpe B, Swinyard BM, Yates JA, Waelkens C. Warm water vapour in the sooty outflow from a luminous carbon star. Nature 2010; 467:64-7. [PMID: 20811453 DOI: 10.1038/nature09344] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 07/07/2010] [Indexed: 11/09/2022]
Abstract
The detection of circumstellar water vapour around the ageing carbon star IRC +10216 challenged the current understanding of chemistry in old stars, because water was predicted to be almost absent in carbon-rich stars. Several explanations for the water were postulated, including the vaporization of icy bodies (comets or dwarf planets) in orbit around the star, grain surface reactions, and photochemistry in the outer circumstellar envelope. With a single water line detected so far from this one carbon-rich evolved star, it is difficult to discriminate between the different mechanisms proposed. Here we report the detection of dozens of water vapour lines in the far-infrared and sub-millimetre spectrum of IRC +10216 using the Herschel satellite. This includes some high-excitation lines with energies corresponding to approximately 1,000 K, which can be explained only if water is present in the warm inner sooty region of the envelope. A plausible explanation for the warm water appears to be the penetration of ultraviolet photons deep into a clumpy circumstellar envelope. This mechanism also triggers the formation of other molecules, such as ammonia, whose observed abundances are much higher than hitherto predicted.
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Affiliation(s)
- L Decin
- Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium.
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Sloan GC, Matsuura M, Zijlstra AA, Lagadec E, Groenewegen MAT, Wood PR, Szyszka C, Bernard-Salas J, van Loon JT. Dust Formation in a Galaxy with Primitive Abundances. Science 2009; 323:353-5. [DOI: 10.1126/science.1165626] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- G. C. Sloan
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - M. Matsuura
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - A. A. Zijlstra
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - E. Lagadec
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - M. A. T. Groenewegen
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - P. R. Wood
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - C. Szyszka
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - J. Bernard-Salas
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
| | - J. Th. van Loon
- Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA
- National Optical Astronomical Observatory of Japan, Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
- School of Physics and Astronomy, University of Manchester, Post Office Box 88, Manchester M6O 1QD, UK
- Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussels, Belgium
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