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arXiv 2408.14971astro-ph.SRphysics.space-ph
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利用 EUHFORIA 探测日冕物质抛射倾角效应

Probing coronal mass ejections inclination effects with EUHFORIA

Karmen Martinić, Eleanna Asvestari, Mateja Dumbović, Tobias Rindlisbacher, Manuela Temmer, Bojan Vršnak

AI总结:

本研究利用 EUHFORIA 三维磁流体动力学模型模拟了两个仅倾角不同的球马克CME,通过81个虚拟航天器数据分析发现CME倾角影响鞘层演化、非径向流及拖曳参数,且鞘层持续时间随径向距离增加而在侧翼增速更快。

摘要:

日冕物质抛射(CMEs)是复杂的磁化等离子体结构,其磁场围绕中心轴螺旋缠绕,形成了所谓的磁通量绳(FR)。FR的中心轴可以与黄道面成任意角度倾斜。在其传播过程中,CME将遭遇既不均匀也不各向同性的行星际磁场和太阳风。因此,具有不同倾角的CME将遭遇不同的背景介质条件,从而CME与其周围环境的相互作用将取决于其FR轴的倾角等因素。本研究旨在理解倾角对CME传播的影响。我们使用 EUHFORIA 三维磁流体动力学模型进行了模拟。本研究聚焦于两个被建模为球马克且特性几乎相同的CME,两者的区别仅在于倾角不同。通过分析分布在日球层内部的81个虚拟航天器集群的模型数据,我们展示了CME倾角对鞘层演化、MHD拖曳和非径向流的影响。我们发现,鞘层持续时间随着远离太阳的径向距离而增加,并且这种增加的速率在CME的侧翼更大。所研究的鞘层区域内的非径向流在黄道面之外表现得更大,这表明行星际磁场在黄道面外发生了“滑动”。我们发现,计算得出的拖曳参数并不随径向距离保持恒定,并且我们无法用现有的数值设置解决拖曳参数对倾角的依赖关系。

英文摘要:

Coronal mass ejections (CMEs) are complex magnetized plasma structures in which the magnetic field spirals around a central axis, forming what is known as a flux rope (FR). The central FR axis can be oriented at any angle to the ecliptic. Throughout its journey, a CME will encounter interplanetary magnetic field and solar wind which are neither homogeneous nor isotropic. Consequently, CMEs with different orientations will encounter different ambient medium conditions and, thus, the interaction of a CME with its surrounding environment will vary depending on the orientation of its FR axis, among other factors. This study aims to understand the effect of inclination on CME propagation. We performed simulations with the EUHFORIA 3D magnetohydrodynamic model. This study focuses on two CMEs modelled as spheromaks with nearly identical properties, differing only by their inclination. We show the effects of CME orientation on sheath evolution, MHD drag, and non-radial flows by analyzing the model data from a swarm of 81 virtual spacecraft scattered across the inner heliospheric. We have found that the sheath duration increases with radial distance from the Sun and that the rate of increase is greater on the flanks of the CME. Non-radial flows within the studied sheath region appear larger outside the ecliptic plane, indicating a "sliding" of the IMF in the out-of ecliptic plane. We found that the calculated drag parameter does not remain constant with radial distance and that the inclination dependence of the drag parameter can not be resolved with our numerical setup.

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