# Photochemistry of O(1D) and O(1S) lines in the coma of 67P/Churyumov-Gerasimenko

Gaël Cessateur, Johan de Keyser, Romain Maggiolo, Andrew Gibbons, Guillaume Gronoff, Herbert Gunell, Frederik Dhooghe, Jérôme Loreau, Nathalie Vaeck, Kathrin Altwegg, et al.

► To cite this version:

Gaël Cessateur, Johan de Keyser, Romain Maggiolo, Andrew Gibbons, Guillaume Gronoff, et al. Photochemistry of O(1D) and O(1S) lines in the coma of 67P/Churyumov-Gerasimenko. EGU General Assembly 2016, Apr 2016, Vienne, Austria. insu-03573511

HAL Id: insu-03573511

https://insu.hal.science/insu-03573511

Submitted on 15 Feb 2022

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

Photochemistry of O(^1D) and O(^1S) lines in the coma of
67P/Churyumov-Gerasimenko

Gaël Cessateur (1), Johan De Keyser (1,2), Romain Maggiolo (1), Andrew Gibbons (1,3), Guillaume Gronoff (4), Herbert Gunell (1), Frederik Dhooghe (3), Jérôme Loreau (3), Nathalie Vaeck (3), Kathrin Altwegg (5,6), Andre Bieler (5,7), Christelle Briois (8), Ursina Calmonte (5), Michael Combi (7), Stephen Fuselier (9,10), Tamas Gombosi (7), Myrtha Haessig (5), Lena Le Roy (5), Eddy Neefs (11), and Martin Rubin (5)

(1) BIRA-IASB, Space Physics Division, Bruxelles, Belgium (gael.cessateur@aeronomie.be), (2) Center for Plasma Astrophysics, Katholieke Universiteit Leuven, Celestijnenlaan 200B, B-3001 Heverlee, Belgium, (3) Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB), Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium, (4) Science Directorate, Chemistry and Dynamics Branch, NASA Langley Research Center, Hampton, Virginia USA; SSAI, Hampton, Virginia USA, (5) Physikalisches Institut, University of Bern, Sidlerstr. 5, CH-3012 Bern, Switzerland, (6) Center for Space and Habitability, University of Bern, Sidlerstr. 5, CH-3012 Bern, Switzerland, (7) Department of Climate and Space Sciences and Engineering, University of Michigan, 2455 Hayward, Ann Arbor, MI 48109, USA, (8) Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 7328 CNRS Université d'Orléans, France, (9) Space Science Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas, 78228, USA, (10) Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas, USA, (11) Engineering Division, Royal Belgian Institute for Space Aeronomy, Ringlaan 3, B-1180, Brussels, Belgium

We present here a chemistry-emission coupled model to study the production and loss mechanisms of the O(¹D) and O(¹S) states, for comet 67P/Churyumov-Gerasimenko. The recent discovery of O₂ in significant abundance relative to water (3.80% +/- 0.85%, Bieler et al. 2015) within the coma of 67P has been taken into consideration for the first time in such models. We evaluate the effect of the presence of O₂ on the green to red-doublet emission intensity ratio, which is traditionally used to assess the CO₂ abundance within cometary atmospheres. Model simulations, solving the continuity equation with transport, show that not taking O₂ into account leads to an underestimation of the CO₂ abundance within 67P. This strongly suggests that the green to red-doublet emission intensity ratio alone is not a proper tool for determining the CO₂ abundance, as previously suggested. O₂ might indeed be a rather common and abundant parent species, following the re-analysis of the comet 1P/Halley data (Rubin et al. 2015). Therefore, it is likely that earlier determinations of the CO₂ abundance in cometary atmospheres have to be revisited.