Energetic Neutral Atoms and Ion Precipitation onto the Upper Atmosphere of Venus
- 1Universität Bern
- 2Swedish Institute of Space Physics
Abstract
Precipitation of space plasma particles on the upper atmosphere of Venus is a key process to understand energy, momentum, and mass transfers between space and the planetary system. We calculate the spatial and directional distribution of the precipitating particles, for ions and energetic neutral atoms (ENAs), and their energy spectra using a global hybrid model with nominal upstream parameters at Venus combined with a solar-zenith-angle-dependent exosphere model. We consider solar wind protons and singly ionized planetary oxygen pickup ions. The ENAs are produced by the charge exchange of the protons and oxygen ions with the neutral exosphere. Approximately 5% of the solar wind protons are found to precipitate in the upper atmosphere of Venus. The precipitation of solar wind in the form of ENAs is found to be small, only ∼0.2% of the solar proton flux. The proton precipitation is solar zenith angle dependent, but it peaks in the subsolar region as expected. The oxygen ion precipitation rate is ∼8 × 10 ²⁶ s ⁻¹ and has a moderate asymmetry with respect to the convective electric field direction. The oxygen ions can reach the nightside but are localized at high latitudes with an energy flux of ∼2 × 10 ⁹ eV cm ⁻² s ⁻¹ . This energy flux is comparable to the energy flux precipitated on the dayside. Although the calculated precipitating proton flux close to the terminator is overestimated by approximately one order of magnitude compared to the flux observed by Venus Express, the angular distribution of ENAs is consistent with the observations.
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BibTeX
@article{obersnel2026energetic,
title = {{Energetic Neutral Atoms and Ion Precipitation onto the Upper Atmosphere of Venus}},
author = {Lorenzo Obersnel and Yoshifumi Futaana and Xiao-Dong Wang and Mats Holmström},
journal = {The Planetary Science Journal},
year = {2026},
month = oct,
doi = {10.3847/psj/aeada1},
url = {https://iopscience.iop.org/article/10.3847/PSJ/aeada1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Energetic Neutral Atoms and Ion Precipitation onto the Upper Atmosphere of Venus
AU - Lorenzo Obersnel
AU - Yoshifumi Futaana
AU - Xiao-Dong Wang
AU - Mats Holmström
PY - 2026
DA - 2026/10/27
JO - The Planetary Science Journal
DO - 10.3847/psj/aeada1
UR - https://iopscience.iop.org/article/10.3847/PSJ/aeada1
AB - Precipitation of space plasma particles on the upper atmosphere of Venus is a key process to understand energy, momentum, and mass transfers between space and the planetary system. We calculate the spatial and directional distribution of the precipitating particles, for ions and energetic neutral atoms (ENAs), and their energy spectra using a global hybrid model with nominal upstream parameters at Venus combined with a solar-zenith-angle-dependent exosphere model. We consider solar wind protons and singly ionized planetary oxygen pickup ions. The ENAs are produced by the charge exchange of the protons and oxygen ions with the neutral exosphere. Approximately 5% of the solar wind protons are found to precipitate in the upper atmosphere of Venus. The precipitation of solar wind in the form of ENAs is found to be small, only ∼0.2% of the solar proton flux. The proton precipitation is solar zenith angle dependent, but it peaks in the subsolar region as expected. The oxygen ion precipitation rate is ∼8 × 10 ²⁶ s ⁻¹ and has a moderate asymmetry with respect to the convective electric field direction. The oxygen ions can reach the nightside but are localized at high latitudes with an energy flux of ∼2 × 10 ⁹ eV cm ⁻² s ⁻¹ . This energy flux is comparable to the energy flux precipitated on the dayside. Although the calculated precipitating proton flux close to the terminator is overestimated by approximately one order of magnitude compared to the flux observed by Venus Express, the angular distribution of ENAs is consistent with the observations.
SN - 2632-3338
ER -