The first widespread solar energetic particle event of solar cycle 25 on 2020 November 29: Shock wave properties and the wide distribution of solar energetic particles
The first widespread solar energetic particle event of solar cycle 25 on 2020 November 29: Shock wave properties and the wide distribution of solar energetic particles
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2020年11月29日太阳周期25的首次广泛传播的太阳高能粒子事件：冲击波特性和太阳高能粒子的广泛分布
DOI：
10.1051/0004-6361/202142515
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发表时间：
2022
影响因子：
6.5
通讯作者：
Rouillard, A. P.
中科院分区：
文献类型：
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作者：
Kouloumvakos, A.;Kwon, R. Y.;Rodríguez-García, L.;Lario, D.;Dresing, N.;Kilpua, E. K.;Vainio, R.;Török, T.;Plotnikov, I.;Rouillard, A. P.
2020年11月29日，从地球上看，位于太阳东部边缘后面的活跃区域发生了一次喷发事件。该事件包括M4.4级耀斑，日冕物质抛射，极紫外光（EUV）波和白光（WL）冲击波。这次喷发引起了第25太阳活动周的第一次广泛的太阳高能粒子（SEP）事件，在四个相距很远的日球层位置（~ 230°）观测到。目的：我们的目标是更好地了解这种广泛的SEP事件的来源，检查日冕激波在SEP广泛分布中的作用，并研究与航天器磁连接的场线处的激波特性。方法利用EUV和WL数据，重建日冕激波的整体三维结构，并计算其运动学。我们确定了日冕和行星际空间的磁场结构，推断了航天器与激波表面的磁连通性，并推导了连接磁力线处激波参数的演变。结果遥感观测显示，日冕激波在火山喷发过程中形成较早，且传播速度快。激波模拟的结果显示，在多个区域形成了强激波，预计将发生有效的粒子加速。在估计的SEP释放时间之前或期间，压力/冲击波被磁连接到所有航天器位置。观测到的近相对论电子的释放主要发生在压力/激波与磁力线连接或激波变为超临界的时间附近，而质子的释放相对于激波变为超临界的时间明显延迟，唯一的例外是帕克太阳探测器上的质子释放。结论冲击波对sep的传播起重要作用。大多数航天器都连接着超临界激波区。地球上的粒子增加，与波几乎没有联系，也表明跨场传输不能被忽视。高能电子的释放似乎发生在冲击波与连接到航天器的磁场线连接或达到超临界的时间附近。高能质子的释放有一个相对于压力/冲击波连接到航天器位置的时间延迟。我们将这种延迟归因于冲击波有效加速质子所需的时间。
ContextOn 2020 November 29, an eruptive event occurred in an active region located behind the eastern solar limb as seen from Earth. The event consisted of an M4.4 class flare, a coronal mass ejection, an extreme ultraviolet (EUV) wave, and a white-light (WL) shock wave. The eruption gave rise to the first widespread solar energetic particle (SEP) event of solar cycle 25, which was observed at four widely separated heliospheric locations (∼230°).AimsOur aim is to better understand the source of this widespread SEP event, examine the role of the coronal shock wave in the wide distribution of SEPs, and investigate the shock wave properties at the field lines magnetically connected to the spacecraft.MethodsUsing EUV and WL data, we reconstructed the global three-dimensional structure of the shock in the corona and computed its kinematics. We determined the magnetic field configurations in the corona and interplanetary space, inferred the magnetic connectivity of the spacecraft with the shock surface, and derived the evolution of the shock parameters at the connecting field lines.ResultsRemote sensing observations show formation of the coronal shock wave occurring early during the eruption, and its rapid propagation to distant locations. The results of the shock wave modelling show multiple regions where a strong shock has formed and efficient particle acceleration is expected to take place. The pressure/shock wave is magnetically connected to all spacecraft locations before or during the estimated SEP release times. The release of the observed near-relativistic electrons occurs predominantly close to the time when the pressure/shock wave connects to the magnetic field lines or when the shock wave becomes supercritical, whereas the proton release is significantly delayed with respect to the time when the shock wave becomes supercritical, with the only exception being the proton release at the Parker Solar Probe.ConclusionsOur results suggest that the shock wave plays an important role in the spread of SEPs. Supercritical shock regions are connected to most of the spacecraft. The particle increase at Earth, which is barely connected to the wave, also suggests that the cross-field transport cannot be ignored. The release of energetic electrons seems to occur close to the time when the shock wave connects to, or becomes supercritical at, the field lines connecting to the spacecraft. Energetic protons are released with a time-delay relative to the time when the pressure/shock wave connects to the spacecraft locations. We attribute this delay to the time that it takes for the shock wave to accelerate protons efficiently.