# Escape and precipitation of planetary ions at Mercury under different solar wind conditions

Sae Aizawa, Nicolas André, Moa Persson, Ronan Modolo, Jim Raines, François Leblanc, Jean-Yves Chaufray, Quentin Nénon

► To cite this version:

Sae Aizawa, Nicolas André, Moa Persson, Ronan Modolo, Jim Raines, et al.. Escape and precipitation of planetary ions at Mercury under different solar wind conditions. 16th Europlanet Science Congress 20, Sep 2022, Granada, Spain. pp.EPSC2022-902, 10.5194/epsc2022-902. insu-04451714

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# Escape and precipitation of planetary ions at Mercury under different solar wind conditions

Sae Aizawa, Nicolas André, Moa Persson, Ronan Modolo, Jim Raines, François Leblanc, Jean-Yves Chaufray, Quentin Nénon

► To cite this version:

Sae Aizawa, Nicolas André, Moa Persson, Ronan Modolo, Jim Raines, et al. Escape and precipitation of planetary ions at Mercury under different solar wind conditions. 16th Europlanet Science Congress 2022 (ESC2022), Sep 2022, Grenade, Spain. pp.EPSC2022-902, 10.5194/epsc2022-902. insu-04451714

HAL Id: insu-04451714

https://insu.hal.science/insu-04451714v1

Submitted on 11 Feb 2024

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
Europlanet Science Congress 2022

Palacio de Congresos de Granada, Spain

18 September – 23 September 2022

EPSC Abstracts

Vol. 16, EPSC2022-902, 2022

https://doi.org/10.5194/epsc2022-902

Europlanet Science Congress 2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

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

Escape and precipitation of planetary ions at Mercury under different solar wind conditions

Sae Aizawa et al.

The escape and precipitation of planetary ions at Mercury under different solar wind conditions have been examined using a global hybrid simulation. The combination of Mercury's weak intrinsic magnetic field and solar wind conditions at Mercury's location results in the formation of a relatively small magnetosphere compared to that of Earth. Its magnetosphere is strongly compressed and may disappear when solar wind conditions are extreme. Under these circumstances, the solar wind can directly interact with its exosphere and surface and the escape of planetary ions is expected to be enhanced. By focusing on the dynamic pressure and interplanetary magnetic field dependence, three different solar wind conditions are used in this study. Under the extreme solar wind planetary protons shows the highest escape rates while planetary sodium ions show the smallest, indicating that the distribution of sodium ions around the planet is controlled by the size of the magnetosphere. As the Larmor radius of planetary sodium ions is larger than that of planetary protons, they cannot escape and instead precipitate onto surface during extreme solar wind conditions, when the dayside magnetosphere is well compressed. Precipitation maps of three components (solar wind protons, planetary protons, and planetary sodium ions) show that the flux from planetary plasmas is sometimes higher than solar wind plasmas, suggesting that the precipitation of planetary plasmas should be considered for the space weathering of Mercury's surface.

**How to cite:** Aizawa, S., Andre, N., Persson, M., Modolo, R., Raines, J., Leblanc, F., Chaufray, J.-Y., and Nenon, Q.: Escape and precipitation of planetary ions at Mercury under different solar wind conditions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-902, https://doi.org/10.5194/epsc2022-902, 2022.

<figure><img src="image_2.png" /></figure>

Discussion

We are sorry, but the discussion is only available for users who registered for the conference. Thank you.
Europlanet Science Congress 2022

Palacio de Congresos de Granada, Spain

18 September – 23 September 2022

EPSC Abstracts

Vol. 16, EPSC2022-902, 2022

https://doi.org/10.5194/epsc2022-902

Europlanet Science Congress 2022

© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

<figure><img src="image_2.png" /></figure>

# Escape and precipitation of planetary ions at Mercury under different solar wind conditions

Sae Aizawa et al.

The escape and precipitation of planetary ions at Mercury under different solar wind conditions have been examined using a global hybrid simulation. The combination of Mercury's weak intrinsic magnetic field and solar wind conditions at Mercury's location results in the formation of a relatively small magnetosphere compared to that of Earth. Its magnetosphere is strongly compressed and may disappear when solar wind conditions are extreme. Under these circumstances, the solar wind can directly interact with its exosphere and surface and the escape of planetary ions is expected to be enhanced. By focusing on the dynamic pressure and interplanetary magnetic field dependence, three different solar wind conditions are used in this study. Under the extreme solar wind planetary protons shows the highest escape rates while planetary sodium ions show the smallest, indicating that the distribution of sodium ions around the planet is controlled by the size of the magnetosphere. As the Larmor radius of planetary sodium ions is larger than that of planetary protons, they cannot escape and instead precipitate onto surface during extreme solar wind conditions, when the dayside magnetosphere is well compressed. Precipitation maps of three components (solar wind protons, planetary protons, and planetary sodium ions) show that the flux from planetary plasmas is sometimes higher than solar wind plasmas, suggesting that the precipitation of planetary plasmas should be considered for the space weathering of Mercury's surface.

**How to cite:** Aizawa, S., Andre, N., Persson, M., Modolo, R., Raines, J., Leblanc, F., Chaufray, J.-Y., and Nenon, Q.: Escape and precipitation of planetary ions at Mercury under different solar wind conditions, Europlanet Science Congress 2022, Granada, Spain, 18–23 Sep 2022, EPSC2022-902, https://doi.org/10.5194/epsc2022-902, 2022.

<figure><img src="image_3.png" /></figure>

## Discussion

We are sorry, but the discussion is only available for users who registered for the conference. Thank you.