讲座信息

讲座题目：The Origin of Underdense Plasma Downflows Associated with Magnetic Reconnection in Solar Eruptions

讲座嘉宾：沈呈彩（美国哈佛-史密松天体物理中心）

讲座主持人：侯义军（国家天文台）

时间：7月15日上午10点

地点：腾讯会议 411-8560-2478 (点此入会）

讲座摘要

Magnetic reconnection is the key mechanism for energy release in solar eruptions, where the high-temperature emissions are primary diagnostic objects for investigating the plasma properties during reconnection processes. A characteristic feature of magnetic reconnection is the production of fast reconnection outflow jets near the plasma Alfvén speeds. Dark finger-shaped plasma downflows moving toward the flare arcade have been commonly regarded as the principal observational evidence for such reconnection-driven outflows in eruptive solar flares. However, they often show a speed much slower than that expected in reconnection theories, challenging the reconnection-driven energy-release scenario in standard flare models. This work employs the three-dimensional magnetohydrodynamics model of solar flares to investigate the plasma flow features in high-temperature reconnection sheets and flare loop-top regions. By comparing the modeled emission with the observed plasma downflow features, we conclude that these dark downflows are self-organized structures formed in a turbulent interface region below the flare termination shock where the outflows meet the flare arcade. We also show that the interface region hosts myriad turbulent flows, electron currents, and shocks, crucial for flare energy release and particle acceleration.

嘉宾介绍

沈呈彩博士，2003年本科毕业于西南师范大学（现西南大学）物理系，2006年至2013年在中科院云南天文台攻读硕士和博士学位。2011年起由联合培养计划在美国哈佛-史密松天体物理中心学习，2013年毕业后工作至今。沈呈彩博士的主要研究内容为太阳爆发的理论和数值模型， 包括耀斑/CME爆发模型以及磁重联的相关内容: 磁重联终止激波和慢激波，磁重联等离子体的非平衡电离态模型和高温等离子的辐射特征等。