Gas phase Elemental abundances in Molecular cloudS (GEMS)

Astronomy and Astrophysics, vol. 637, pp. A39

Abstract

Context. Sulphur is one of the most abundant elements in the Universe. Surprisingly, sulphuretted molecules are not as abundant as expected in the interstellar medium and the identity of the main sulphur reservoir is still an open question. Aims. Our goal is to investigate the H 2 S chemistry in dark clouds, as this stable molecule is a potential sulphur reservoir. Methods. Using millimeter observations of CS, SO, H 2 S, and their isotopologues, we determine the physical conditions and H 2 S abundances along the cores TMC 1-C, TMC 1-CP, and Barnard 1b. The gas-grain model N AUTILUS is used to model the sulphur chemistry and explore the impact of photo-desorption and chemical desorption on the H 2 S abundance. Results. Our modeling shows that chemical desorption is the main source of gas-phase H 2 S in dark cores. The measured H 2 S abundance can only be fitted if we assume that the chemical desorption rate decreases by more than a factor of 10 when n H > 2 × 10 4 . This change in the desorption rate is consistent with the formation of thick H 2 O and CO ice mantles on grain surfaces. The observed SO and H 2 S abundances are in good agreement with our predictions adopting an undepleted value of the sulphur abundance. However, the CS abundance is overestimated by a factor of 5−10. Along the three cores, atomic S is predicted to be the main sulphur reservoir. Conclusions. The gaseous H 2 S abundance is well reproduced, assuming undepleted sulphur abundance and chemical desorption as the main source of H 2 S. The behavior of the observed H 2 S abundance suggests a changing desorption efficiency, which would probe the snowline in these cold cores. Our model, however, highly overestimates the observed gas-phase CS abundance. Given the uncertainty in the sulphur chemistry, we can only conclude that our data are consistent with a cosmic elemental S abundance with an uncertainty of a factor of 10.

Authors 33

1. D. Navarro-Almaida

   Spanish National Observatory

   Affiliation as printed

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

2. Romane Le Gal

   Center for Astrophysics Harvard & Smithsonian

   Affiliation as printed

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

3. Asunción Fuente

   Spanish National Observatory

   Affiliation as printed

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

4. P. Riviére-Marichalar

   Spanish National Observatory

   Affiliation as printed

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

5. Valentine Wakelam

   Centre National de la Recherche Scientifique · Laboratoire d'Astrophysique de Bordeaux

   Affiliation as printed

   Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France

   Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France

6. Stéphanie M. Cazaux Aachen

   Leiden University · Delft University of Technology

   Affiliation as printed

   Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands; University of Leiden, P.O. Box 9513, NL, 2300 RA, Leiden, The Netherlands

   Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands

   University of Leiden, PO Box 9513, 2300 RA Leiden, The Netherlands

7. P. Caselli

   Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany

   Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany

8. J. Laas

   Max Planck Institute for Extraterrestrial Physics

   Affiliation as printed

   Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany

   Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany

9. T. Alonso‐Albi

   Spanish National Observatory

   Affiliation as printed

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

   Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

10. Jean‐Christophe Loison

    Centre National de la Recherche Scientifique · Institut des Sciences Moléculaires

    Affiliation as printed

    Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, F-33400, Talence, France

    Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France

11. Maryvonne Gérin

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · École Normale Supérieure - PSL · Sorbonne Université · Université Pierre-et-Marie-Curie

    Affiliation as printed

    Observatoire de Paris, PSL Research University, CNRS, École Normale Supérieure, Sorbonne Universités, UPMC Univ. Paris 06, 75005, Paris, France

    Observatoire de Paris, PSL Research University, CNRS, École Normale Supérieure, Sorbonne Universités, UPMC Univ. Paris 06, 75005 Paris, France

12. Carsten Kramer

    Instituto de Radioastronomía Milimétrica

    Affiliation as printed

    Instituto Radioastronomía Milimétrica (IRAM), Av. Divina Pastora 7, Nucleo Central, 18012, Granada, Spain

    Instituto Radioastronomía Milimétrica (IRAM), Av. Divina Pastora 7, Nucleo Central, 18012 Granada, Spain

13. E. Roueff

    Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Université · Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères

    Affiliation as printed

    Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190, Meudon, France

    Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, 92190 Meudon, France

14. R. Bachiller

    Spanish National Observatory

    Affiliation as printed

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

15. Benoît Commerçon

    Lyon 1 Université · École Normale Supérieure de Lyon · Centre National de la Recherche Scientifique · Centre de Recherche Astrophysique de Lyon

    Affiliation as printed

    École Normale Supérieure de Lyon, CRAL, UMR CNRS 5574, Université Lyon I, 46 Allée d'Italie, 69364, Lyon Cedex 07, France

    École Normale Supérieure de Lyon, CRAL, UMR CNRS 5574, Université Lyon I, 46 allée d’Italie, 69364 Lyon Cedex 07, France

16. Rachel Friesen

    National Radio Astronomy Observatory

    Affiliation as printed

    National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville VA USA 22901

    National Radio Astronomy Observatory, 520 Edgemont Rd., Charlottesville VA 22901, USA

17. S. García‐Burillo

    Spanish National Observatory

    Affiliation as printed

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

18. Javier R. Goicoechea

    Consejo Superior de Investigaciones Científicas · Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006, Madrid, Spain

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006 Madrid, Spain

19. Barbara Michela Giuliano

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany

20. Izaskun Jiménez-Serra

    Consejo Superior de Investigaciones Científicas · Centro de Astrobiología

    Affiliation as printed

    Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850, Madrid, Spain

    Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain

21. Jason M. Kirk

    University of Lancashire

    Affiliation as printed

    Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK

22. Valerio Lattanzi

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany

23. J. Malinen

    University of Helsinki · University of Cologne

    Affiliation as printed

    Department of Physics, University of Helsinki, PO Box 64, 00014, Helsinki, Finland

    Institute of Physics I, University of Cologne, Cologne, Germany

    Department of Physics, University of Helsinki, PO Box 64, 00014 Helsinki, Finland

24. Nuria Marcelino

    Consejo Superior de Investigaciones Científicas · Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006, Madrid, Spain

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006 Madrid, Spain

25. R. Martín-Doménech

    Center for Astrophysics Harvard & Smithsonian

    Affiliation as printed

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

26. Guillermo M. Muñoz Caro

    Consejo Superior de Investigaciones Científicas · Centro de Astrobiología

    Affiliation as printed

    Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850, Madrid, Spain

    Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain

27. Jaime E. Pineda

    Max Planck Institute for Extraterrestrial Physics

    Affiliation as printed

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany

    Centre for Astrochemical Studies, Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748 Garching, Germany

28. B. Tercero

    Spanish National Observatory

    Affiliation as printed

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

29. Sandra P. Treviño-Morales

    Chalmers University of Technology

    Affiliation as printed

    Chalmers University of Technology, Department of Space, Earth and Environment, SE-412 93 Gothenburg, Sweden

    Chalmers University of Technology, Department of Space, Earth and Environment, 412 93 Gothenburg, Sweden

30. Octavio Roncero

    Consejo Superior de Investigaciones Científicas · Instituto de Física Fundamental

    Affiliation as printed

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006, Madrid, Spain

    Instituto de Física Fundamental (CSIC), Calle Serrano 123, 28006 Madrid, Spain

31. A. Hacar Aachen Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Leiden Observatory, Leiden University, PO Box 9513, 2300-RA, Leiden, The Netherlands

    Leiden Observatory, Leiden University, PO Box 9513, 2300, Leiden, The Netherlands

32. Mario Tafalla

    Spanish National Observatory

    Affiliation as printed

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014, Madrid, Spain

    Observatorio Astronómico Nacional (OAN), Alfonso XII, 3, 28014 Madrid, Spain

33. Derek Ward-Thompson

    University of Lancashire

    Affiliation as printed

    Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK