Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A82 | |
Number of page(s) | 11 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202450728 | |
Published online | 27 September 2024 |
Varying water activity and momentum transfer on comet 67P/Churyumov-Gerasimenko from its non-gravitational forces and torques
1
Instituto de Astrofísica de Andalucía - CSIC,
Glorieta de la Astronomía s/n,
18008
Granada,
Spain
2
Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3,
38106
Braunschweig,
Germany
3
Aix Marseille Univ, CNRS, CNES, Laboratoire d’Astrophysique de Marseille,
Marseille,
France
4
DLR Institut für Planetenforschung,
Rutherfordstraße 2,
12489
Berlin,
Germany
5
Institute for Theoretical Physics, Johannes Kepler University Linz,
Austria
6
Alma Mater Studiorum - Università di Bologna, Dipartimento di Ingegneria Industriale,
Via Fontanelle 40,
47121
Forlì,
Italy
7
Zuse Institute Berlin,
14195
Berlin,
Germany
8
CNRS, Laboratoire J.-L. Lagrange, Observatoire de la Côte d’Azur,
Boulevard de l’Observatoire, CS 34229 -
06304
NICE Cedex 4,
France
★ Corresponding author; attree@iaa.es
Received:
15
May
2024
Accepted:
19
August
2024
Aims. We investigate the ability of a simultaneous fitting of comet 67P/Churyumov-Gerasimenko’s non-gravitational forces, torques, and total water-outgassing rate, as observed by Rosetta, to constrain complex thermophysical models of cometary material.
Methods. We extend the previous work of fitting geographically defined surface outgassing models to the Rosetta observations by testing the effects of a more detailed geomorphological mapping, the resolution of the shape-model used, self-heating by neighbouring facets on the shape-model, thermal inertia in the outgassing solution, and the variation in the momentum coupling between the gas and the nucleus. We also directly compare the non-gravitational acceleration curves available in the literature.
Results. We correct an error in the calculation of pole-orientation in the previous paper. We find that, under the assumptions of the model, non-gravitational forces and torques are driven by water sublimation from the nucleus, thermal inertia and self-heating have only minor effects, spatially uniform activity cannot explain 67P’s non-gravitational dynamics, spatially uniform momentum transfer cannot explain 67P’s non-gravitational dynamics, and different terrain types have different instantaneous responses to insolation.
Conclusions. Consolidated terrain facing south on 67P/Churyumov-Gerasimenko has a high outgassing flux, a steep response to insolation, and a large gas momentum transfer coefficient. Instead, that facing north behaves differently, producing little to no water outgassing, and with a lower momentum transfer efficiency. Dusty terrain also has a lower outgassing rate and momentum transfer efficiency, and either depletes its volatile component or is buried in fall-back as the comet approaches the Sun. Momentum transfer appears correlated with insolation, likely due to an increased enhancement in the gas temperature as the dust it flows through is heated.
Key words: methods: data analysis / celestial mechanics / comets: general / 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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