Issue |
A&A
Volume 662, June 2022
|
|
---|---|---|
Article Number | A81 | |
Number of page(s) | 17 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202142990 | |
Published online | 21 June 2022 |
CRIRES high-resolution near-infrared spectroscopy of diffuse interstellar band profiles
Detection of 12 new DIBs in the YJ band and the introduction of a combined ISM sight line and stellar analysis approach★
1
Institut für Astro- und Teilchenphysik, Universität Innsbruck,
Technikerstr. 25/8,
6020
Innsbruck,
Austria
e-mail: alexander.ebenbichler@uibk.ac.at
2
Department of Astronomy and Astrophysics, University of Chicago,
5640 S Ellis Avenue,
Chicago,
IL
60637,
USA
3
Dr. Karl Remeis-Sternwarte & Erlangen Centre for Astroparticle Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg,
Sternwartstr. 7,
96049
Bamberg,
Germany
4
LMU München, Universitätssternwarte,
Scheinerstr. 1,
81679
München,
Germany
5
European Southern Observatory,
Alonso de Cordova 3107, Vitacura, Casilla
19001
Santiago,
Chile
6
Laboratory for Astrophysics, Leiden Observatory, Leiden University,
PO Box 9513,
2300 RA
Leiden,
The Netherlands
Received:
23
December
2021
Accepted:
28
February
2022
Aims. A high spectral resolution investigation of diffuse interstellar bands (DIBs) in the near-infrared (YJ band) is conducted to test new methods, to confirm and improve existing parameters, and to search for new DIBs.
Methods. The CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES) on the European Southern Observatory's Very Large Telescope was employed to obtain spectra of four reddened background supergiant stars (HD 183143, HD 165784, HD 92207, HD 111613) and an unreddened comparison star (HD 87737) at the highest resolution of R ≈ 100 000 currently achievable at near-infrared wavelengths, more than twice as high as accomplished in previous near-infrared DIB studies. The correction for telluric absorption was performed by a modelling approach. Non-local thermodynamic equilibrium spectral modelling of available optical and the new near-infrared stellar spectra facilitated a comprehensive characterisation of the atmospheric properties of the background stars. As a consequence, a more precise and accurate determination of the reddening and the reddening law along the respective sight lines could be achieved than feasible before by comparison of the observed and model spectral energy distributions. For DIBs that overlap with stellar lines the DIB profile shapes could be recovered.
Results. Seventeen known near-infrared DIBs were confirmed, and 12 previously unknown and generally weaker DIBs were identified in the YJ band. Three DIBs that show uniform profiles along all sight lines were identified, possibly connected to transitions from a common lower state of the same carrier. The divergent extinction curve towards the frequently discussed DIB standard star HD 183143 could be reproduced for the first time, requiring extra absorption by ~3.5 mag due to polycyclic aromatic hydrocarbons (PAHs) to match the ultraviolet extinction bump. This extra absorption probably stems from a circumstellar bubble lying in front of the star which is intersected tangentially by the line of sight, making this particular sight line more peculiar than standard.
Key words: dust, extinction / ISM: lines and bands / ISM: molecules / line: profiles / stars: early-type / supergiants
DIB spectra is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/662/A81
© A. Ebenbichler et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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