Issue |
A&A
Volume 674, June 2023
|
|
---|---|---|
Article Number | A153 | |
Number of page(s) | 8 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/202245711 | |
Published online | 16 June 2023 |
Solar-wind electron precipitation on weakly magnetized bodies: The planet Mercury
1
Laboratoire Lagrange, OCA, UCA, CNRS,
96 Bd de l’Observatoire,
06304
Nice, France
e-mail: federico.lavorenti@oca.eu
2
Dipartimento di Fisica “E. Fermi”, Univ. di Pisa,
L.go Bruno Pontecorvo 3,
56127
Pisa, Italy
3
LPC2E, CNRS, Univ. d’Orléans, OSUC, CNES,
3 Av. de la Recherche Scientifique,
45071
Orléans, France
4
LASP, Univ. of Colorado Boulder,
1234 Innovation Drive
Boulder, CO
80303, USA
5
IMPACT, NASA/SSERVI,
3400 Marine St.,
Boulder, CO
80303, USA
6
LATMOS, UVSQ,
11 Bd D’Alembert,
78280
Guyancourt, France
7
School of Physics & Astronomy, University of Leicester,
University Rd
LE1 7RH,
Leicester, UK
8
IRAP, UPS, CNRS, CNES,
9 Av. du Colonel Roche,
31028
Toulouse, France
9
JAXA,
3-1-1 Yoshinodai, Chuo-ku, Sagamihara-shi,
Kanagawa, Japan
10
ESA/ESTEC,
Keplerlaan 1,
2200 AG
Noordwijk, The Netherlands
Received:
17
December
2022
Accepted:
4
May
2023
Rocky objects in the Solar System (such as planets, asteroids, moons, and comets) undergo a complex interaction with the flow of magnetized, supersonic plasma emitted from the Sun called solar wind. We address the interaction of such a flow with the planet Mercury, considered here as the archetype of a weakly magnetized, airless, telluric body immersed in the solar wind. Due to the lack of dense atmosphere, a considerable fraction of solar-wind particles precipitate on Mercury. The interaction processes between precipitating electrons and other nonionized parts of the system remain poorly understood. Shading light on such processes is the goal of this work. Using a 3D fully kinetic self-consistent plasma model, we show for the first time that solar-wind electron precipitation drives (i) efficient ionization of multiple neutral exosphere species and (ii) emission of X-rays from the surface of the planet. We conclude that, compared to photoionization, electron-impact ionization should not be considered a secondary process for the H, He, O, and Mn exosphere. Moreover, we provide the first, independent evidence of X-ray aurora-like emission on Mercury using a numerical approach.
Key words: planets and satellites: magnetic fields / plasmas / X-rays: general / planets and satellites: aurorae / solar wind / planet-star interactions
© The Authors 2023
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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