发表机构
Key Laboratory of Solar Activity and Space Weather, School of Aerospace, Harbin Institute of Technology, Shenzhen; Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick; G-LAMP NEXUS Institute/School of Space Research, Kyung Hee University; Centro de Investigacion en Astronomía, Universidad Bernardo O’Higgins; Institute of Solar-Terrestrial Physics SB RAS（哈尔滨工业大学深圳航天学院太阳活动与空间天气重点实验室; 华威大学物理部聚变、太空与天体物理中心; 庆熙大学太空研究学院 G-LAMP NEXUS 研究所; 贝尔纳多·奥希金斯大学天文学研究中心; 俄罗斯科学院西伯利亚分院太阳-地球物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究日冕流带中斜向传播的扭结波，发现斜度降低相速度并改变波结构，忽略斜度会低估阿尔芬速度达1.5倍，需立体观测确定传播方向。
AI 中文摘要
日冕物质抛射（CME）冲击激发的日冕流带扭结波常被用于估算日冕阿尔芬速度。这些估算通常假设波沿平衡磁场方向平行传播，而该磁场在天空平面内径向向外指向太阳。然而，CME 冲击的几何结构自然允许斜向传播。我们研究了由包含中央电流片的等离子体片引导的斜向传播扭结波的性质，该电流片代表日冕流带茎。我们同时考虑了冷和暖流带等离子体，并分析了传播斜度对波色散、本征函数和日震学诊断的影响。我们发现，增加传播斜度会降低相速度，这既源于投影效应，也源于相速度对传播角的内在依赖。波结构也经历从体模到表面模的逐渐转变，导致片边界处扰动增强和波局域化加剧。因此，对于 CME 冲击给定的能量沉积，斜向扭结波预计会产生比场向波更大的可观测振幅。将所发展的理论应用于先前报道的流带波，我们推断出阿尔芬速度在 50-500 km/s 范围内。我们表明，忽略波传播斜度可能会低估阿尔芬速度高达 1.5 倍。这些结果表明，在流带波的日冕日震学中应考虑波传播斜度，并且需要立体观测来约束真实的传播方向。
英文摘要
Coronal streamer kink waves excited by an impact of coronal mass ejections (CMEs) are routinely used to estimate the coronal Alfvén speed. These estimates generally assume wave propagation parallel to the equilibrium magnetic field directed radially outward to the Sun, in the plane of the sky. However, the geometry of CME impacts naturally allows for oblique propagation. We investigate the properties of obliquely propagating kink waves guided by a plasma slab with a central current sheet representing a coronal streamer stalk. We consider both cold and warm streamer plasmas and analyse influence of propagation obliquity on wave dispersion, eigenfunctions, and seismological diagnostics. We find that increasing the propagation obliquity reduces the phase speed owing to both projection effects and the intrinsic dependence of the phase speed on the propagation angle. The wave structure also undergoes a gradual transition from a body mode to a surface mode, leading to stronger perturbations at the slab boundaries and enhanced wave localization. Consequently, for a given energy deposited by a CME impact, oblique kink waves are expected to produce larger observable amplitudes than field-aligned waves. Applying the developed theory to streamer waves reported previously, we infer Alfvén speeds in the range of 50-500 km/s. We show that neglecting wave propagation obliquity may underestimate the Alfvén speed by up to a factor of 1.5. These results demonstrate that wave propagation obliquity should be taken into account in coronal seismology of streamer waves and that stereoscopic observations will be required to constrain the true propagation direction.
