@article{Wedlund:2019:0004-6361/201834881,
author = {Wedlund, Simon C and Behar, E and Nilsson, H and Alho, M and Kallio, E and Gunell, H and Bodewits, D and Heritier, K and Galand, M and Beth, A and Rubin, M and Altwegg, K and Volwerk, M and Gronoff, G and Hoekstra, R},
doi = {0004-6361/201834881},
journal = {Astronomy and Astrophysics},
title = {Solar wind charge exchange in cometary atmospheres III. Results from the Rosetta mission to comet 67P/Churyumov-Gerasimenko},
url = {http://dx.doi.org/10.1051/0004-6361/201834881},
volume = {630},
year = {2019}
}

Download

TY  - JOUR
AB  - Solar wind charge-changing reactions are of paramount importance to thephysico-chemistry of the atmosphere of a comet. The ESA/Rosetta mission tocomet 67P/Churyumov-Gerasimenko (67P) provides a unique opportunity to studycharge-changing processes in situ. To understand the role of these reactions inthe evolution of the solar wind plasma, and interpret the complex in-situmeasurements made by Rosetta, numerical or analytical models are necessary. Weuse an extended analytical formalism describing solar wind charge-changingprocesses at comets along solar wind streamlines. The model is driven by solarwind ion measurements from the Rosetta Plasma Consortium-Ion CompositionAnalyzer (RPC-ICA) and neutral density observations from the RosettaSpectrometer for Ion and Neutral Analysis-Comet Pressure Sensor (ROSINA-COPS),as well as charge-changing cross sections of hydrogen and helium particles in awater gas. A mission-wide overview of charge-changing efficiencies at comet 67Pis presented. Electron capture cross sections dominate and favor the productionof He and H energetic neutral atoms, with fluxes expected to rival those of H+and He2+ ions. Neutral outgassing rates are retrieved from local RPC-ICA fluxmeasurements, and match ROSINA's estimates very well. From the model, we findthat solar wind charge exchange is unable to fully explain the magnitude of thesharp drop of solar wind ion fluxes observed by Rosetta for heliocentricdistances below 2.5 AU. This is likely because the model does not take intoaccount the relative ion dynamics and, to a lesser extent, ignore the formationof bow shock-like structures upstream of the nucleus. This work also shows thatthe ionization by solar EUV radiation and energetic electrons dominates thesource of cometary ions, although solar wind contributions may be significantduring isolated events.
AU  - Wedlund,Simon C
AU  - Behar,E
AU  - Nilsson,H
AU  - Alho,M
AU  - Kallio,E
AU  - Gunell,H
AU  - Bodewits,D
AU  - Heritier,K
AU  - Galand,M
AU  - Beth,A
AU  - Rubin,M
AU  - Altwegg,K
AU  - Volwerk,M
AU  - Gronoff,G
AU  - Hoekstra,R
DO  - 0004-6361/201834881
PY  - 2019///
SN  - 0004-6361
TI  - Solar wind charge exchange in cometary atmospheres III. Results from the Rosetta mission to comet 67P/Churyumov-Gerasimenko
T2  - Astronomy and Astrophysics
UR  - http://dx.doi.org/10.1051/0004-6361/201834881
UR  - http://arxiv.org/abs/1902.04417v1
UR  - http://hdl.handle.net/10044/1/71502
VL  - 630
ER  - 

Download