AI 中文总结
研究利用SDO/AIA和SolO/EUI同时观测日冕慢磁声波，通过时间距离分析量化波衰减。发现LoS与波传播方向夹角是决定慢波表观衰减的关键，校正观测效应有助于推断潜在物理耗散过程。
AI 中文摘要
几十年来，日冕中一直能观测到慢磁声波，但现有理论无法完全解释观测到的衰减长度范围，不同仪器测量结果也常不一致。本文展示了两个事件，利用SDO/AIA和Solar Orbiter/EUI-HRIEUV同时观测黑子锚定日冕扇羽中的慢波。事件1中视线（LoS）夹角16.2度，事件2中LoS几乎平行。通过时间距离分析，识别出3分钟波段的波并用指数折叠长度量化波衰减。LoS不平行时，两仪器测量的衰减长度比变化大；LoS平行时，衰减长度一致且比值约为1。结果表明LoS与波传播方向夹角是决定慢波表观衰减的关键因素，而这一因素尚未被系统考虑。由于衰减长度的统计研究限制日冕能量损失机制，必须校正简单投影之外的观测效应以可靠推断潜在物理耗散过程。
英文摘要
Slow magnetoacoustic waves have been observed in the solar corona for decades; yet, existing theories do not fully explain the wide range of observed decay lengths, and measurements from different instruments frequently disagree. We present two events with simultaneous SDO/AIA and Solar Orbiter/EUI-HRIEUV observations of slow waves in sunspot-anchored coronal fan feathers. In Event 1, the LoS are separated by 16.2 degrees, while in Event 2, they are almost parallel. Using time-distance analysis, we identify waves with periods in the 3-minute band and quantify wave decay using the exponential folding length. When LoS are non-parallel, the ratio of decay lengths measured by the two instruments, $λ_\mathrm{ratio} = λ_{\mathrm{AIA}} / λ_{\mathrm{EUI}}$ varies widely, with both $λ_\mathrm{ratio} > 1$ and $λ_\mathrm{ratio} < 1$ observed. However, when the LoS are almost parallel, the decay lengths agree with one another, and $λ_\mathrm{ratio} \approx 1$. These results show that the angle between the LoS and the wave propagation direction is key to determining the apparent decay of slow waves, a factor that has not yet been systematically accounted for. Since statistical studies of decay lengths constrain coronal energy-loss mechanisms, observational effects beyond simple projection must be corrected to reliably infer the underlying physical dissipation processes.
CommentsAccepted for publication in Philosophical Transactions of the Royal Society A
