Issue |
A&A
Volume 687, July 2024
|
|
---|---|---|
Article Number | A78 | |
Number of page(s) | 14 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202449554 | |
Published online | 01 July 2024 |
Sublimation of volatiles from H2O:CO2 bulk ices in the context of comet 67P/Churyumov–Gerasimenko
II. Noble gases★
1
Space Research & Planetary Sciences, Physics Institute, University of Bern,
Sidlerstrasse 5,
3012
Bern,
Switzerland
e-mail: niels.ligterink@unibe.ch
2
Center for Space and Habitability, University of Bern,
Gesellschaftsstrasse 6,
3012
Bern,
Switzerland
3
Faculty of Aerospace Engineering, Delft University of Technology,
Delft,
The Netherlands
e-mail: niels.ligterink@tudelft.nl
Received:
9
February
2024
Accepted:
15
April
2024
Context. The ROSINA instrument on board the Rosetta spacecraft measured, among others, the outgassing of noble gases from comet 67P/Churyumov–Gerasimenko. The interpretation of this dataset and unravelling underlying desorption mechanisms requires detailed laboratory studies.
Aims. We aim to improve our understanding of the desorption patterns, trapping, and fractionation of noble gases released from the H2O:CO2-dominated ice of comet 67P.
Methods. In the laboratory, ice films of neon, argon, krypton, or xenon (Ne, Ar, Kr, and Xe) mixed in CO2:H2O were prepared at 15 K. Temperature-programmed desorption mass spectrometry is employed to analyse the desorption behaviour of the noble gases. Mass spectrometric ROSINA data of 67P were analysed to determine the fraction of argon associated with CO2 and H2O, respectively.
Results. CO2 has a significant effect on noble gas desorption behaviour, resulting in the co-release of noble gases with CO2, decreasing the amount of noble gas trapped within water, shifting the pure phase noble gas peak desorption temperature to lower temperatures, and prolonging the trapping of neon. These effects are linked to competition for binding sites in the water ice and the formation of crystalline CO2. Desorption energies of the pure phase noble gas release were determined and found to be higher than those previously reported in the literature. Enhancement of the Ar/Kr and Ar/Xe ratios are at best 40% and not significantly influenced by the addition of CO2. Analysis of ROSINA mass spectrometric data shows that the fraction of argon associated with H2O is 0.53 ± 0.30, which cannot be explained by our laboratory results.
Conclusions. Multicomponent ice mixtures affect the desorption behaviour of volatiles compared to simple binary mixtures and experiments on realistic cometary ice analogues are vital to understanding comet outgassing.
Key words: solid state: volatile / methods: laboratory: molecular / methods: laboratory: solid state / comets: individual: 67P/Churyumov–Gerasimenko
© The Authors 2024
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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