太阳高能电子事件  

Solar energetic electrons events

作　　者：王雯 王玲华 Wang Wen;Wang Linghua(Institute of Space Physics&Applied Technology(ISPAT),Peking University,Beijing 100871,China)

机构地区：[1]北京大学空间物理与应用技术研究所,北京100871

出　　处：《地球与行星物理论评（中英文）》2023年第4期385-397,共13页Reviews of Geophysics and Planetary Physics

基　　金：国家自然科学基金资助项目(42127803,42150105);民用航天“十三五”技术预先研究日球层边际探测重要科学问题资助项目(D020301)。

摘　　要：太阳高能粒子事件是行星际中观测到的最常见的太阳粒子加速现象之一.太阳高能粒子事件根据主导粒子的不同可以分为质子主导的大太阳高能粒子事件和电子主导的富含3He/电子太阳高能粒子事件.其主要区分为大太阳高能粒子事件中,^(3)He/^(4)He~5×10^(-4)比率与日冕相同,而电子主导的富含3He/电子太阳高能粒子事件,^(3)He/^(4)He>0.01,远高于日冕.太阳高能电子事件在太阳上的释放时间可以分为低能(~10 keV以下)电子和高能(~15 keV以上)电子两组,高能电子相较于低能电子延迟释放~20 min,对应此时日冕物质抛射高度距日心约2个太阳半径,而与之相关的富含3He离子的释放相较于电子释放延迟1小时左右,对应此时日冕物质抛射高度距日心约5.7个太阳半径.太阳高能电子事件的能谱一般呈现为双幂律谱形式,低能谱指数1.9±0.3和高能谱指数3.6±0.7,弯折能量~60 keV,低能谱指数与高能谱指数呈现明显正相关,而低能高能谱指数与弯折能量没有明显相关;也有部分事件呈现单幂律谱的形式,谱指数为3.5±1.2.前人统计研究发现,约有~45%的15 keV以上有观测的太阳高能电子事件与硬X射线耀斑相关,通过比较50 keV以上,太阳高能电子事件能谱以及相关联X射线耀斑的能谱发现,这些事件中的高能硬X射线谱指数与电子事件高能能谱指数呈现正相关,但与经典韧致辐射理论预测不符合;并且通过对高能电子事件电子总数的估算发现,高能电子事件的电子总数仅为耀斑中产生硬X射线的电子总数的~0.1%~1%.本文更进一步地研究了16个同时具有良好电子观测(能量覆盖5~200 keV)和硬X射线观测(能量覆盖3~80 keV)的电子事件,根据电子通过相对论厚靶韧致辐射机制产生X射线可以反推出产生硬X射线的电子能谱,通过对比电子能谱指数和产生硬X射线的电子谱指数发现,低能电子谱指数与产生硬X射线的电子谱指数Solar energetic electron events are one of the most common solar particle accelerations observed in the interplanetary medium(IPM).According to the different dominant species,solar particle events can be divided into proton-dominated large solar energetic particle events and electron-dominated 3He/electron-rich solar energe-tic particle events.The main difference is that in the proton-dominated large solar energetic particle event,the ratio of ^(3)He/^(4)He~5×10^(−4) is the same as that of the corona,and the electron-dominated 3He/electron-rich solar energetic particle event,^(3)He/^(4)He>0.01,much higher than that of the corona.The release time of solar energetic electron events on the sun can be divided into two groups:low-energy(below~10 keV)electrons and high-energy(above~15 keV)electrons.Compared with low-energy electrons,the release time of high-energy electrons is delayed by~20 minutes,which corresponds to the coronal mass ejection height being about 2 solar radii away from the center of the sun.The release of 3He ions is delayed by about an hour compared to electron release,which corresponds to the coronal mass ejection height being about 5.7 solar radii away from the center of the sun.The energy spectrum of solar energetic electron events is generally a double power-law shape,with a low-energy spectral index of 1.9±0.3 and a high-energy spectral index of 3.6±0.7 with a break energy of~60 keV.The low-energy spectral in-dex and the high-energy spectral index show a significant positive correlation,while the low-energy and high-energy spectral index show no significant correlation with the break energy.Some events show a single power-law spectrum with an index of 3.5±1.2.Previous statistical studies have found that~45%of the observed solar high-energy electron events above 15 keV are related to hard X-ray flares.By comparing energies above 50 keV,the high-energy hard X-ray spectral index in these events is positively correlated with the high-energy spectral index of electron events,while the index rel

关 键 词：太阳高能电子 粒子加速 太阳耀斑 

分 类 号：P353.8[天文地球—空间物理学]