ATOMIUM: halide molecules around the S-type AGB star W Aquilae

Astronomy and Astrophysics, vol. 655, pp. A80

Abstract

Context. S-type asymptotic giant branch (AGB) stars are thought to be intermediates in the evolution of oxygen- to carbon-rich AGB stars. The chemical compositions of their circumstellar envelopes are also intermediate but have not been studied in as much detail as their carbon- and oxygen-rich counterparts. W Aql is a nearby S-type star, with well-known circumstellar parameters, making it an ideal object for in-depth study of less common molecules. Aims. We aim to determine the abundances of AlCl and AlF from rotational lines, which have been observed for the first time towards an S-type AGB star. In combination with models based on PACS observations, we aim to update our chemical kinetics network based on these results. Methods. We analyse ALMA observations towards W Aql of AlCl in the ground and first two vibrationally excited states and AlF in the ground vibrational state. Using radiative transfer models, we determine the abundances and spatial abundance distributions of Al35Cl, Al37Cl, and AlF. We also model HCl and HF emission and compare these models to PACS spectra to constrain the abundances of these species. Results. AlCl is found in clumps very close to the star, with emission confined within 0′′.1 of the star. AlF emission is more extended, with faint emission extending 0′′.2 to 0′′.6 from the continuum peak. We find peak abundances, relative to H2, of 1.7 × 10−7 for Al35Cl, 7 × 10−8 for Al37Cl, and 1 × 10−7 for AlF. From the PACS spectra, we find abundances of 9.7 × 10−8 and ≤10−8, relative to H2, for HCl and HF, respectively. Conclusions. The AlF abundance exceeds the solar F abundance, indicating that fluorine synthesised in the AGB star has already been dredged up to the surface of the star and ejected into the circumstellar envelope. From our analysis of chemical reactions in the wind, we conclude that AlF may participate in the dust formation process, but we cannot fully explain the rapid depletion of AlCl seen inthe wind.

Authors 37

1. T. Danilovich

   KU Leuven

   Affiliation as printed

   Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

   Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

2. Marie Van de Sande

   KU Leuven

   Affiliation as printed

   Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

   Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

3. John M. C. Plane

   University of Leeds

   Affiliation as printed

   University of Leeds, School of Chemistry, Leeds LS2 9JT, UK

   School of Chemistry [Leeds] (Faculty of Mathematics and Physical Sciences, Woodhouse Lane, Leeds LS2 9JT - United Kingdom)

4. Thomas James Millar

   Queen's University Belfast

   Affiliation as printed

   Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK

   ARC - Astrophysics Research Centre [Belfast] (School of Mathematics and Physics, QUB, Belfast, County Antrim BT7 INN - Ireland)

5. P. Royer

   KU Leuven

   Affiliation as printed

   Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

   Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

6. K. Hammami

   Tunis El Manar University

   Affiliation as printed

   LSAMA, Department of Physics, Faculty of Sciences, University Tunis El Manar, Campus Universitaire, 1060 Tunis, Tunisia

   LSAMA - Laboratoire de Spectroscopie Atomique, Moléculaire et Applications (Department of Physics 2092 Tunis - Tunisia)

7. C. A. Gottlieb

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

   Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA

   CfA - Harvard-Smithsonian Center for Astrophysics (60 Garden Street, Cambridge, MA 02138, USA - United States)

8. L. Decin

   University of Leeds · KU Leuven

   Affiliation as printed

   Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

   University of Leeds, School of Chemistry, Leeds LS2 9JT, UK

   Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

   School of Chemistry [Leeds] (Faculty of Mathematics and Physical Sciences, Woodhouse Lane, Leeds LS2 9JT - United Kingdom)

9. Anita M. S. Richards

   University of Manchester

   Affiliation as printed

   JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

   JBCA - Jodrell Bank Centre for Astrophysics (School of Physics and Astronomy, University of Manchester M13 9PL - United Kingdom)

10. E. De Beck

    Chalmers University of Technology

    Affiliation as printed

    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden

    OSO - Onsala Space Observatory (Chalmers University of Technology, SE-439 92 Onsala, Sweden - Sweden)

11. A. Baudry

    Université de Bordeaux · Laboratoire d'Astrophysique de Bordeaux

    Affiliation as printed

    Université de Bordeaux, Laboratoire d’Astrophysique de Bordeaux, 33615 Pessac, France

    LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac] (Bât B18N - Allée Geoffroy Saint Hilaire CS 50023 - 33615 Pessac Cedex France - France)

12. J. Bolte

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

13. Emily Cannon

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

14. Frederik De Ceuster

    University College London · KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    University College London, Department of Physics and Astronomy, London WC1E 6BT, UK

    Department of Physics and Astronomy [UCL London] (Gower Street, London WC1E 6BT, UK - United Kingdom)

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

15. A. de Koter

    University of Amsterdam · KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    University of Amsterdam, Anton Pannekoek Institute for Astronomy, 1090 GE Amsterdam, The Netherlands

    AI PANNEKOEK - Astronomical Institute Anton Pannekoek (PO Box 94249, 1090 GE Amsterdam - Netherlands)

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

16. S. Etoka

    University of Manchester

    Affiliation as printed

    JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

    JBCA - Jodrell Bank Centre for Astrophysics (School of Physics and Astronomy, University of Manchester M13 9PL - United Kingdom)

17. D. Gobrecht

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

18. M. D. Gray

    University of Manchester · National Astronomical Research Institute of Thailand

    Affiliation as printed

    JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

    National Astronomical Research Institute of Thailand, Chiangmai 50180, Thailand

    JBCA - Jodrell Bank Centre for Astrophysics (School of Physics and Astronomy, University of Manchester M13 9PL - United Kingdom)

    National Astronomical Research Institute of Thailand, Thailand, puji.irawati@gmail.com (Thailand)

19. F. Herpin

    Université de Bordeaux · Laboratoire d'Astrophysique de Bordeaux

    Affiliation as printed

    Université de Bordeaux, Laboratoire d’Astrophysique de Bordeaux, 33615 Pessac, France

    LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac] (Bât B18N - Allée Geoffroy Saint Hilaire CS 50023 - 33615 Pessac Cedex France - France)

20. W. Homan

    Université Libre de Bruxelles · KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles (ULB), CP 226, 1060 Brussels, Belgium

    IAA - Institut d'Astronomie et d'Astrophysique [Bruxelles] (CP-226, Boulevard du Triomphe, B-1050 Brussels - Belgium)

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

21. M. Jeste

    Max Planck Institute for Radio Astronomy

    Affiliation as printed

    Max-Planck-Institut für Radioastronomie, 53121 Bonn, Germany

    MPIFR - Max-Planck-Institut für Radioastronomie (Auf dem Hügel 69 D-53121 Bonn - Germany)

22. P. Kervella

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d’études spatiales et d’instrumentation en astrophysique

    Affiliation as printed

    LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France

    LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (5, place Jules Janssen 92190 MEUDON - France)

23. T. Khouri

    Chalmers University of Technology

    Affiliation as printed

    Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden

    OSO - Onsala Space Observatory (Chalmers University of Technology, SE-439 92 Onsala, Sweden - Sweden)

24. E. Lagadec

    Université Côte d'Azur · Lagrange Laboratory · Observatoire de la Côte d’Azur

    Affiliation as printed

    Université Côte d’Azur, Laboratoire Lagrange, Observatoire de la Côte d’Azur, 06304 Nice Cedex 4, France

    Observatoire de la Côte d'Azur (France)

25. Silke Maes

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

26. Jolien Malfait

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

27. Iain McDonald

    The Open University · University of Manchester · KU Leuven

    Affiliation as printed

    JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

    School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

    OU - The Open University [Milton Keynes] (Walton Hall, Kents Hill, Milton Keynes MK7 6AA - United Kingdom)

28. K. M. Menten

    Max Planck Institute for Radio Astronomy

    Affiliation as printed

    Max-Planck-Institut für Radioastronomie, 53121 Bonn, Germany

    MPIFR - Max-Planck-Institut für Radioastronomie (Auf dem Hügel 69 D-53121 Bonn - Germany)

29. M. Montargès

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d’études spatiales et d’instrumentation en astrophysique

    Affiliation as printed

    LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France

    LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (5, place Jules Janssen 92190 MEUDON - France)

30. Holger S P Müller

    University of Cologne

    Affiliation as printed

    Universität zu Köln, I. Physikalisches Institut, 50937 Köln, Germany

    Universität zu Köln = University of Cologne (Albertus-Magnus-Platz, 50923 Köln - Germany)

31. B. Pimpanuwat

    University of Manchester · National Astronomical Research Institute of Thailand · KU Leuven

    Affiliation as printed

    JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

    National Astronomical Research Institute of Thailand, Chiangmai 50180, Thailand

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

    National Astronomical Research Institute of Thailand, Thailand, puji.irawati@gmail.com (Thailand)

32. R. Sahai

    California Institute of Technology · Jet Propulsion Laboratory

    Affiliation as printed

    California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA 91109, USA

    JPL - Jet Propulsion Laboratory (4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA - United States)

33. S. H. J. Wallström

    KU Leuven

    Affiliation as printed

    Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

34. L. B. F. M. Waters Aachen SRON Netherlands Institute for Space Research SRON - SRON Netherlands Institute for Space Research (SRON Groningen

    Radboud University Nijmegen · Space Research Organisation Netherlands

    Affiliation as printed

    Radboud University, Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Nijmegen, The Netherlands

    SRON Netherlands Institute for Space Research, 3584 CA Utrecht, The Netherlands

    IMAPP - Institute for Mathematics, Astrophysics and Particle Physics (P.O. Box 9010, 6500 GL Nijmegen - Netherlands)

    SRON - SRON Netherlands Institute for Space Research (SRON Groningen, Landleven 12, 9747 AD Groningen - SRON Utrecht, Sorbonnelaan 2, 3584 CA Utrecht - Netherlands)

35. K. T. Wong

    Institut de Radioastronomie Millimétrique

    Affiliation as printed

    Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 Saint Martin d’Hères, France

    IRAM - Institut de RadioAstronomie Millimétrique (300 rue de la Piscine, Domaine Universitaire 38406 Saint Martin d'Hères - France)

36. Jeremy A. Yates

    University College London

    Affiliation as printed

    University College London, Department of Physics and Astronomy, London WC1E 6BT, UK

    Department of Physics and Astronomy [UCL London] (Gower Street, London WC1E 6BT, UK - United Kingdom)

37. Albert A. Zijlstra

    University of Manchester · Cyberport · University of Hong Kong · KU Leuven

    Affiliation as printed

    JBCA, Department Physics and Astronomy, University of Manchester, Manchester M13 9PL, UK

    University of Hong Kong, Laboratory for Space Research, Pokfulam, Hong Kong

    Institute of Astronomy [Leuven] (Celestijnenlaan 200D BUS 2401, 3001 Leuven - Belgium)

    LSR - Laboratory for Space Research [Hong Kong] (Cyberport 4, Hong Kong - China)