C60+ diffuse interstellar band correlations and environmental variations

Astronomy and Astrophysics, vol. 656, pp. L17

Abstract

Context. The diffuse interstellar bands (DIBs) are absorption features seen in the spectra of astronomical objects that arise in the interstellar medium. Today, more than 500 DIBs have been observed, mostly in the optical and near-infrared wavelengths. The origin of the DIBs is unclear; only ionised buckminsterfullerene, C60+, has been identified as a viable candidate for two strong and three weaker DIBs. Aims. We investigate the correlations between the strengths of the two strongest C60+ DIBs as well as their environmental behaviour. Methods. We analysed measurements of the strengths of the two C60+ DIBs at 9577 and 9633 Å for 26 lines of sight. We used two different methods, including Monte Carlo simulations, to study their correlations and the influence of measurement errors on the correlation coefficients. We examined how the strength of the C60+ DIBs changes as a result of different environmental conditions, as measured by the concentration of H/H2 and the strength of the ambient UV radiation. Results. In contrast to results recently reported by Galazutdinov et al. (2021, AJ, 161, 127), we find a high correlation between the strengths of the C60+ DIBs. We also discovered that the behaviour of the correlated C60+ bands is quite distinct from other DIBs at 5780, 5797, and 6203 Å in different environments.

Authors 4

1. Leander Schlarmann Aachen ILEWG EMMESI EuroMoonMars Earth Space Innovation Huygens Laboratory

   Leiden University · University of Vienna · Leiden Observatory

   Affiliation as printed

   Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria

   ILEWG EMMESI EuroMoonMars Earth Space Innovation, Leiden Observatory, Universiteit Leiden, Huygens Laboratory, J.H. Oort Building, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands

2. Bernard H. Foing Aachen ILEWG EMMESI EuroMoonMars Earth Space Innovation Huygens Laboratory

   Leiden University · Leiden Observatory

   Affiliation as printed

   ILEWG EMMESI EuroMoonMars Earth Space Innovation, Leiden Observatory, Universiteit Leiden, Huygens Laboratory, J.H. Oort Building, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands

3. 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

4. Haoyu Fan

   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