Issue |
A&A
Volume 645, January 2021
|
|
---|---|---|
Article Number | A8 | |
Number of page(s) | 6 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361/202039823 | |
Published online | 21 December 2020 |
CF+ excitation in the interstellar medium
1
LOMC – UMR 6294, CNRS-Université du Havre,
25 rue Philippe Lebon, BP 1123,
76063
Le Havre Cedex, France
e-mail: benjamin.desrousseaux@univ-lehavre.fr
2
Instituto de Física Fundamental (CSIC). Calle Serrano 121-123,
28006
Madrid, Spain
3
Department of Chemistry, Missouri University of Science and Technology,
Rolla,
Missouri
65409, USA
Received:
1
November
2020
Accepted:
24
November
2020
The detection of CF+ in interstellar clouds potentially allows astronomers to infer the elemental fluorine abundance and the ionization fraction in ultraviolet-illuminated molecular gas. Because local thermodynamic equilibrium (LTE) conditions are hardly fulfilled in the interstellar medium (ISM), the accurate determination of the CF+ abundance requires one to model its non-LTE excitation via both radiative and collisional processes. Here, we report quantum calculations of rate coefficients for the rotational excitation of CF+ in collisions with para- and ortho-H2 (for temperatures up to 150 K). As an application, we present non-LTE excitation models that reveal population inversion in physical conditions typical of ISM photodissociation regions (PDRs). We successfully applied these models to fit the CF+ emission lines previously observed toward the Orion Bar and Horsehead PDRs. The radiative transfer models achieved with these new rate coefficients allow the use of CF+ as a powerful probe to study molecular clouds exposed to strong stellar radiation fields.
Key words: ISM: general / masers / scattering / molecular data / radiative transfer
© B. Desrousseaux et al. 2020
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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