Major Electron Events and Coronal Magnetic Configurations of the Related Solar Active Regions

Abstract

A statistical survey of 26 major electron events during the period 2002 February through the end of solar cycle 23 is presented. We have obtained electron solar onset times and the peak flux spectra for each event by fitting to a power-law spectrum truncated by an exponential high-energy tail, i.e., f (E) ∼ E −δ e −E/E 0 . We also derived the coronal magnetic configurations of the related solar active regions (ARs) from the potential-field source-surface (PFSS) model. It is found that: (1) 10 of the 11 well-connected open field-line events are prompt events whose solar onset times coincide with the maxima of flare emission. 13 of the 14 closed field-line events are delayed events. (2) A not-well-connected open field-line event and one of the closed field-line events are prompt events, they are both associated with large-scale coronal disturbances or dimming. (3) An averaged harder spectrum is found in open field-line events compared with the closed ones. Specifically, the averaged spectral index δ is of 1.6 ± 0.3 in open field-line events and of 2.0 ± 0.4 in closed ones. The spectra of three closed fieldline events show infinite rollover energies E 0 . These correlations clearly establish a significant link between the coronal magnetic field-line topology and the escape of charged particles from the flaring ARs into interplanetary space during the major solar energetic particle (SEP) events.

Electron and Proton Acceleration During the First Ground Level Enhancement Event of Solar Cycle 24

“…These lines may provide escaping channels for particles accelerated at low coronal sites. By applying the same model, a statistical link between the coronal magnetic topologies and dynamics of in-situ electrons was recently established (Li et al 2010). For individual SEP event, a more practical and accurate method to construct coronal magnetic fields is absolutely necessary (Li et al 2011).…”

Coronal Jets, Magnetic Topologies, and the Production of Interplanetary Electron Streams

“…These recent progresses in identifying the solar source still leave unsolved questions: Do the jets or CMEs in association with the impulsive SEP events play a critical role in particle acceleration (Mason et al 2009)? How does the magnetic topology in the source region relate solar activities to the in-situ SEP dynamics (Li et al 2010)? To answer the questions, careful comparison of in-situ particle measurements and remote-sensing solar observations, as well as the modeling of coronal magnetic fields should be carried out.…”

空间天气驱动源—太阳风暴研究

“…在粒子注入过程中, 能谱变软和变各 向同性, 这说明了粒子加速源从一个局部区域转变 为空间上扩展 CME 驱动的激波, 这意味着耀斑和 CME 过程均加速了粒子. Li 等 [180] 通过分析 WIND 资 料, 发现在大型的 SEP 事件中, 除 CME 激波加速之 外, 耀斑加速和日冕磁场位行对行星际高能粒子的 动力学状态也有重要影响. Shen 等 [181] 改进了计算阿 尔文波速度和激波强度的方法, 证实由于激波产生 的日冕条件不同, 一个慢 CME 驱动了强激波, 而快 的 CME 却只有一个相对较弱的激波, 与射电和 SEP 的观测符合.…”