文章基本信息

标题：First direct observation of a torsional Alfvén oscillation at coronal heights ⋆
本地全文：下载
作者：P. Kohutova ; E. Verwichte ; C. Froment 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2020
卷号：633
页码：1-5
DOI：10.1051/0004-6361/201937144
语种：English
出版社：EDP Sciences
摘要：Context.Torsional Alfvén waves are promising candidates for the transport of energy across different layers of the solar atmosphere. They have been predicted theoretically for decades. Previous detections of Alfvén waves so far have however mostly relied on indirect signatures.Aims.We present the first direct observational evidence of a fully resolved torsional Alfvén oscillation of a large-scale structure occurring at coronal heights.Methods.We analysed IRIS imaging and spectral observation of a surge resulting from magnetic reconnection between active region prominence threads and surrounding magnetic field lines.Results.The IRIS spectral data provide clear evidence of an oscillation in the line-of-sight velocity with a 180° phase difference between the oscillation signatures at opposite edges of the surge flux tube. This together with an alternating tilt in the Si IV and Mg II k spectra across the flux tube and the trajectories traced by the individual threads of the surge material provide clear evidence of torsional oscillation of the flux tube.Conclusions.Our observation shows that magnetic reconnection leads to the generation of large-scale torsional Alfvén waves.
关键词：enmagnetohydrodynamics (MHD)Sun: coronaSun: oscillationsSun: magnetic fields