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arXiv 2501.06950astro-ph.SR
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太阳粒子加速

Solar Particle Acceleration

Donald V. Reames

AI总结:

本文综述太阳高能粒子加速的两类主导机制:CME驱动激波导致的缓变型事件与磁重联相关的脉冲型事件,并阐明激波俘获、波放大及再加速等过程。

摘要:

高能粒子可能在恒星日冕中被广泛加速;其过程很可能与我们在太阳上发现的相同。在此,我们已经认识到两种主导太阳高能粒子(SEPs)加速的物理机制。最高能量和最强强度产生于“缓变型”事件,即由快速、宽幅日冕物质抛射(CMEs)从太阳驱动的冲击波处。规模较小但数量更多、具有异常粒子成分的“脉冲型”事件,则产生于太阳喷流和耀斑中的磁重联期间。喷流提供开放磁力线,使SEPs得以逃逸;闭合磁环则约束这种能量,产生明亮而炽热的耀斑,甚至可能通过大量纳米耀斑促进低日冕加热。流动质子会在激波上游放大Alfvén波。这些波散射并俘获SEPs,并在大型事件中改变元素丰度、使上游低能谱变平。当条件允许时,激波还会再加速来自早期脉冲型事件的残余离子;这些离子通常主导高能重离子丰度。大型CME驱动的激波会发展出极宽的经度跨度,以高能粒子填充内日球层的大部分区域。

英文摘要:

High-energy particles may be accelerated widely in stellar coronae; probably by the same processes we find in the Sun. Here, we have learned of two physical mechanisms that dominate the acceleration of solar energetic particles (SEPs). The highest energies and intensities are produced in "gradual" events at shock waves driven from the Sun by fast, wide coronal mass ejections (CMEs). Smaller, but more numerous, "impulsive" events with unusual particle composition are produced during magnetic reconnection in solar jets and flares. Jets provide open magnetic field lines where SEPs escape; closed magnetic loops contain this energy to produce bright, hot flares, perhaps even contributing to heating the low corona in profuse nanoflares. Streaming protons amplify Alfven waves upstream of the shocks. These waves scatter and trap SEPs and, in large events, modify the element abundances and flatten the low-energy spectra upstream. Shocks also reaccelerate residual ions from earlier impulsive events, when available, that characteristically dominate the energetic heavy-ion abundances. The large CME-driven shock waves develop an extremely wide longitude span, filling much of the inner heliosphere with energetic particles.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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