The EDIBLES survey

Astronomy and Astrophysics, vol. 695, pp. A212

Abstract

Context. Numerous studies of diffuse interstellar band (DIB) profiles have detected substructures, which in turn suggests that large molecules are acting as their carriers. However, some of the narrowest DIBs generally do not show such substructures, suggesting the possibility of very small carriers. Aims. Based on the previously found tight correlation of the three narrow DIBs at 6196, 6440, and 6623 Å and the present detection of weaker side DIBs to each of them in the extensive dataset from the ESO Diffuse Interstellar Bands Large Exploration Survey, we investigated whether they may stem from small linear carrier molecules. This approach can lead to concrete DIB carrier suggestions, which can be tested in laboratory measurements in future studies. Methods. We suggest that the DIBs we studied here represent individual rotational transitions of a small molecule. We determined the molecular constants from observations and compared them with data from a large set of quantum-chemical calculations to constrain possible carrier candidates. Furthermore, we determined the rotational temperatures by fitting line ratios using the fitted molecular models. Results. We determined molecular constants for three DIB systems and the corresponding transition types. The fitted rotational temperatures lie within the range of known interstellar diatomic molecules. We identified several DIB carrier candidates, almost all of them molecular ions. Some of them are metastable species, indicating the possibility of collision complexes as DIB carriers. Conclusions. If our hypothesis holds, this would be a major step towards the identification of a carrier molecule of the 6196 Å DIB, the strongest among the narrow DIBs.

Authors 14

1. A. Ebenbichler

   Universität Innsbruck

   Affiliation as printed

   Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria

2. Milan Ončák

   Universität Innsbruck

   Affiliation as printed

   Universität Innsbruck, Institut für Ionenphysik und Angewandte Physik, Technikerstr. 25, 6020 Innsbruck, Austria

3. N. Przybilla

   Universität Innsbruck

   Affiliation as printed

   Universität Innsbruck, Institut für Astro- und Teilchenphysik, Technikerstr. 25/8, 6020 Innsbruck, Austria

4. Helgi Rafn Hróðmarsson

   Centre National de la Recherche Scientifique · Université Paris-Est Créteil · Université Paris Cité · Laboratoire Interuniversitaire des Systèmes Atmosphériques

   Affiliation as printed

   Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, 75013 Paris, France

5. Jonathan V. Smoker

   Royal Observatory · European Southern Observatory · UK Astronomy Technology Centre

   Affiliation as printed

   European Southern Observatory, Alonso de Cordova 3107, Vitacura, Santiago, Chile

   UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

6. Rosine Lallement

   Centre National de la Recherche Scientifique · Université Paris Sciences et Lettres · Observatoire de Paris · Sorbonne Paris Cité · Galaxies, Etoiles, Physique et Instrumentation · Université Paris Diderot

   Affiliation as printed

   GEPI, Observatoire de Paris, PSL Research University, CNRS, Université Paris-Diderot, Sorbonne Paris Cité, Place Jules Janssen, 92195 Meudon, France

7. Amin Farhang

   Institute for Research in Fundamental Sciences

   Affiliation as printed

   School of Astronomy, Institute for Research in Fundamental Sciences, 19395-5531 Tehran, Iran

8. Charmi Bhatt

   Western University

   Affiliation as printed

   Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada

   Institute for Earth and Space Exploration, The University of Western Ontario, London, ON N6A 3K7, Canada

9. J. Cami

   Western University · Search for Extraterrestrial Intelligence

   Affiliation as printed

   Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada

   Institute for Earth and Space Exploration, The University of Western Ontario, London, ON N6A 3K7, Canada

   SETI Institute, 189 Bernardo Ave, Suite 100, Mountain View, CA 94043, USA

10. Martin Cordiner

    Goddard Space Flight Center · Catholic University of America

    Affiliation as printed

    Astrochemistry Laboratory, NASA Goddard Space Flight Center, Code 691, 8800 Greenbelt Road, Greenbelt, MD 20771, USA

    Department of Physics, The Catholic University of America, Washington, DC 20064, USA

11. P. Ehrenfreund Aachen Laboratory for Astrophysics, Leiden Observatory

    Leiden University · Leiden Observatory

    Affiliation as printed

    Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

12. N. L. J. Cox
    Affiliation as printed

    Centre d’Etudes et de Recherche de Grasse, ACRI-ST, Av. Nicolas Copernic, Grasse 06130, France

13. Jacco Th. van Loon

    Keele University

    Affiliation as printed

    Lennard-Jones Laboratories, Keele University ST5 5BG, UK

14. Bernard H. Foing Aachen Laboratory for Astrophysics, Leiden Observatory

    Leiden University · Leiden Observatory · European Space Research and Technology Centre

    Affiliation as printed

    ESTEC, ESA, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands

    LUNEX EMMESI Euromoonmars Earth Space Innovation, SBIC Noordwijk, The Netherlands

    Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands