Proton Plasma Asymmetries between the Convective-Electric-Field Hemispheres of Venus' Dayside Magnetosheath

IF 1.7 4区地球科学 Q3 ASTRONOMY & ASTROPHYSICS

Annales Geophysicae Pub Date : 2023-12-06 DOI:10.5194/egusphere-2023-2570

Sebastián Rojas Mata, Gabriella Stenberg Wieser, Tielong Zhang, Yoshifumi Futaana

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Abstract

Abstract. Proton plasma asymmetries with respect to the convective electric field (E) are characterized in Venus’ dayside magnetosheath using measurements taken by an ion mass-energy spectrometer and a magnetometer. Investigating the spatial structure of the magnetosheath plasma in this manner provides insight into the coupling between solar-wind protons and planetary ions. A previously developed methodology for statistically quantifying asymmetries is further developed and applied to an existing database of proton bulk-parameter measurements in the dayside magnetosheath. The density and speed exhibit weak asymmetries favoring the hemisphere in which E points towards the planet, while the magnetic-field strength has a weak asymmetry favoring the opposite hemisphere. The temperatures perpendicular and parallel to the background magnetic field as well as their ratio present no significant asymmetries. Deflection of the solar wind due to momentum exchange with planetary ions is revealed by (1) the O⁺ Larmor-radius trends of the asymmetries of the bulk-velocity components perpendicular to the upstream solar-wind flow and (2) the E×B_IMF -drift trends of the bulk-velocity component along the cross-flow component of the interplanetary magnetic field (B_IMF). These interpretations are enabled by comparisons to studies of solar-wind deflection at Mars and comet 67P/Churyumov-Gerasimenko, highlighting the benefits of comparative planetology studies.

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金星日侧磁鞘对流电场半球间质子等离子体的不对称性

摘要。质子等离子体相对于对流电场(E)的不对称性在金星的日侧磁鞘中被离子质能谱仪和磁力计测量表征。以这种方式研究磁鞘等离子体的空间结构可以深入了解太阳风质子和行星离子之间的耦合。一种先前开发的统计量化不对称的方法被进一步开发，并应用于日光侧磁鞘中质子体积参数测量的现有数据库。密度和速度表现出微弱的不对称，有利于E指向行星的半球，而磁场强度则表现出微弱的不对称，有利于相反的半球。垂直和平行于背景磁场的温度及其比值没有明显的不对称性。(1)垂直于上游太阳风流的体速分量的不对称性的O+ larmorr -半径趋势和(2)体速分量沿行星际磁场横流分量(BIMF)的E×BIMF -漂移趋势揭示了太阳风与行星离子动量交换引起的偏转。这些解释是通过与火星和67P/Churyumov-Gerasimenko彗星太阳风偏转的研究进行比较而实现的，突出了比较行星学研究的好处。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Annales Geophysicae 地学-地球科学综合

CiteScore

4.30

自引率

0.00%

发文量

审稿时长

2 months

期刊介绍： Annales Geophysicae (ANGEO) is a not-for-profit international multi- and inter-disciplinary scientific open-access journal in the field of solar–terrestrial and planetary sciences. ANGEO publishes original articles and short communications (letters) on research of the Sun–Earth system, including the science of space weather, solar–terrestrial plasma physics, the Earth''s ionosphere and atmosphere, the magnetosphere, and the study of planets and planetary systems, the interaction between the different spheres of a planet, and the interaction across the planetary system. Topics range from space weathering, planetary magnetic field, and planetary interior and surface dynamics to the formation and evolution of planetary systems.