X射线耀斑的分析及其与Ha耀斑的比较

本文利用SMM卫星的X射线资料,以及云南天文台的光学观测资料,分析了1980年7月14日的3B级耀斑.求得X射线耀斑能谱随时间的变化;计算了耀斑爆发时加速的电子总数和电子的平均能量;并测量和比较了Hα耀斑和X射线爆源的位置.结果表明:(1)硬X射线爆由高能非热电子束引起;(2)软X射线爆基本上由高温等离子体的热韧致辐射所产生,但必须考虑非热电子轫致辐射的贡献;(3)确定X射线爆源的高度,有赖于耀斑模型及活动区磁场位形.所得结果支持耀斑过程的新浮磁流模型(EMF模型).     

1986年2月太阳的高活动I活动区4711的演化和特征

本文使用太阳黑子、磁场、Hα色球、10.7cm射电及软X射线流量等观测资料,对太阳活动谷期的高活动区4711(SESC编号)从光球、色球和日冕三个方面做了综述.指出该活动区演化过程的特征是:(1)黑子群在主要发展阶段呈一个紧密的结构复杂的强磁区;(2)两次大的太阳爆发均发生在黑子群面积衰减阶段的初期;(3)黑子群的转动可能是活动区日冕加热和耀斑活动的主要供能机制;(4)色球暗条的频繁活动是爆发的先兆;(5) 10.7cm射电辐射和软X射线辐射的逐日流量有彼此不重合的双峰.      

日面耀斑环中物质的运动

利用云南天文台1980年7月14日3B级双带耀斑的光学观测资料,以及SMM卫星对同一耀斑的X射线观测结果,讨论日面耀斑环中物质的运动规律。先比较耀斑Hα象和X射线象的日面位置,根据投影效应确定耀斑环的高度;然后从理论上估算由于耀斑环中物质下落,所形成的耀斑活动区视向速度的分布。所得结果与观测资料基本相符。      

1980年7月14日耀斑和磁流浮现模型

本文利用云南天文台耀斑H_α巡视观测、活动区白光照相及速度场资料,结合SMM的X射线资料和北京天文台的射电观测资料,对1980年7月14日日面3B级大耀斑进行了综合研究。对照耀斑过程的磁流浮现(EMF)模型,我们分析了活动区的形态变化特征,估算了耀斑释放的磁能、耀斑过程的特征时间及耀斑爆发时加速的电子总数和加速电子的平均能量。结果表明:(1)耀斑过程的EMF模型与观测结果基本符合,可以认为EMF模型能够较好地说明耀斑的物理过程。(2)根据对速度场资料及耀斑产生位置的分析,初步认为电流片可能位于速度中性线与磁中性线的交点处及其附近,或速度中性线与暗条的交点处及其附近[3]。(3)观测和计算表明,硬x射线爆是由电流片中加速的高能非热电子所产生,而软X射线爆则由耀斑区的高温等离子体的热轫致辐射所产生。      

1984年5月21日耀斑环珥的Hα-SSHG观测研究

利用云南天文台太阳光谱分光照相仪(Hα-SSHG),拍摄了1984年5月21日边缘耀斑环珥的Hα光谱资料,结合Hα色球观测资料给出了该事件的发展过程和色球、光谱的形态特征。定性地探讨了该耀斑环内的宏观物质运动.用提出的双环系模型能较好地解释观测结果.      

太阳耀斑硬X射线高能时延和辐射展宽

本文从耀斑高能电子束流与太阳大气相互作用产生硬X射线辐射的基本事实出发,根据观测资料,提出了一个流量与能谱同步变化的注入源函数模型,研究太阳大气(靶物质)密度对耀斑硬X射线时间响应.理论计算与观测事实基本一致.主要计算结果如下:高能时延与辐射展宽是耀斑硬X射线轫致辐射时间特征的二种表现,硬X射线发射区的太阳大气密度越低,高能时延与辐射展宽效应越明显,二者之间存在显著的相关性.      

用半经验模型研究耀斑大气的能量耗散

本文利用南京大学太阳塔多波段光谱资料推求出的两个耀斑(一个SB级,一个2B级)的半经验模型;计算了耀斑不同时刻的辐射损失速率,并与电子束轰击和X线作用下的产能率作了比较.结果表明,耀斑不同时刻的色球辐射损失变化可达一个量级以上;耀斑脉冲相前后电子束轰击加热相当有效;耀斑强度极大时,电子束轰击和X线加热都有作用;耀斑主相时,X线加热更能有效地平衡辐射损失.但是,尤其是对大耀斑来说,色球低层和光球上层的加热既不能用电子束轰击,也不能用X线的作用来解释;可能存在某种把能量从色球上层向低层转移的机制.研究也表明,耀斑随时间变化的半经验模型为研究耀斑的能量耗散过程提供了很好的工具.      

众眼看宇宙

2012年伊始,NASA就将这幅高清的X级太阳耀斑照片赠予世人欣赏。太阳耀斑（又称色球爆发）是太阳表面突然释放能量,喷射出高能带电粒子而形成的壮观场面,其寿命仅有几分钟至几个小时。     

太阳耀斑硬X射线能谱演变特征

太阳硬X射线是耀斑高能电子束流与太阳大气相互作用产生的韧致辐射,根据简单的太阳耀斑环物理模型,假定具有流量与能谱同步变化的高能电子束流从耀斑环顶部注入,计算了硬X射线辐射在不同的靶物质密度区的能谱演变特征。结果表明:硬X射线辐射在低大气密度靶区呈现软一硬一硬的能谱演变特征,在高密度靶区硬X射线能谱则具有软一硬一软的变化特征。高能电子束流持续时间影响谱型转变区域在耀斑环中的高度。      

第21～24太阳周4类空间天气事件爆发特征统计分析

对第21～24太阳周不同等级的太阳X射线耀斑事件、太阳质子事件、地磁暴事件及高能电子增强事件的爆发频次特征进行统计,结果表明:太阳周耀斑爆发的总数量与该太阳周的黑子数峰值呈正比,耀斑总数、X级耀斑事件数与峰值的相关系数分别为0.974,0.997;太阳质子事件主要发生在峰年前后1～2年,约占总发生次数的80%,峰值通量大于10pfu （1 pfu=1 cm-2·sr-1·s-1）的质子事件中,84%伴有耀斑爆发,并且主要伴随M或X级耀斑,少量伴随C级耀斑,峰值通量大于1000pfu的质子事件中,98%伴随M或X级耀斑,并且以X级耀斑为主;第21,22,23和24太阳周发生地磁暴最频繁的时间分别在1982,1991,2003年和2015年,分别滞后黑子数峰值时间3年、2年、2年和1年;72%的高能电子增强事件发生在太阳周下降期,24%的高能电子增强事件发生在太阳周上升期.      

Evidence of the radio-quiet hard X-ray precursor of the 13 December 2006 solar flare

We report multi-wavelength investigation of the pre-impulsive phase of the 13 December 2006 X-class solar flare. We use hard X-ray data from the anticoincidence system of spectrometer onboard INTEGRAL (ACS) jointly with soft X-ray data from the GOES-12 and Hinode satellites. Radio data are from Nobeyama and Learmonth solar observatories and from the Culgoora Solar Radio Spectrograph. The main finding of our analysis is a spiky increase of the ACS count rate accompanied by surprisingly gradual and weak growth of microwave emission and without detectable radio emission at meter and decimeter wavelengths about 10 min prior to the impulsive phase of the solar flare. At the time of this pre-flare hard X-ray burst the onset of the GOES soft X-ray event has been reported, positive derivative of the GOES soft X-ray flux started to rise and a bright spot has appeared in the images of the Hinode X-ray telescope (XRT) between the flare ribbons near the magnetic inversion line close to the sources of thermal and non-thermal hard X-ray emission observed by Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) during the flare. These facts we consider as evidences of solar origin of the increased pre-flare ACS count rate. We briefly discuss a possible cause of the pre-flare emission peculiarities.     

Relative positions of microwave and hard X-ray burst sources

Simultaneous microwave and hard X-ray imaging observations of 12 bursts show that it is difficult to discern a general pattern between microwave and hard X-ray burst locations. In general, the microwave source is displaced from the hard X-ray source. The commonly believed behavior of the microwave source being located near the top and hard X-ray source near the footpoints of a loop appears to be true in some cases but not all. If the burst source is simple, both may be located near loop tops. Sometimes when the hard X-ray source has two components, one weak and one strong, the microwave source is not located over a neutral line (loop top) but close to a sunspot where the magnetic field is strongest. It appears that more than one loop or arcade may sometimes be involved in the microwave and hard X-ray emission. This is particularly true when several interacting loops trigger the onset of a flare.     

Solar maximum mission experiment: Early results of the hard X-ray imaging experiment

We have selected four widely different flares from the early period of operations of the Hard X-Ray Imaging Spectrometer (HXIS) on SMM to illustrate the characteristic imaging properties of this experiment. For the small flare of April 4, 1980, we demonstrate the instrument's capability for locating a compact source. In the weak, but extensive, flare of April 6 we show how well the instrument can display spatial structure, and also the low level of the instrument background. In the 1B flare of April 7 we are able to locate positions of the X-ray emission in the soft and hard channels, and estimate the positional variations of the emission patches. Finally, in the IN flare of April 10, which produced the strongest hard X-ray burst we have seen so far, we repeat some of the studies made for the April 7 event, and also demonstrate the capability of the HXIS instrument to study the development, with high time resolution, of individual 8″ × 8″ elements of the flare.     

应用高频多普勒方法对耀斑期间电离层TEC变化的估算

通过分析前人对耀斑期间电离层各区域电子密度的变化情况,总结了一个应用耀斑期间的高频多普勒扰动记录估算出层总电子含量变化的方法,并应用这一方法计算了１９９０年３－６月几次耀斑引起的低电离层总电子含量的变化,同时还与各耀斑对应的最大流量密度进行了比较,并对两者之间的相关情况进行了分析。     

一个亚耀斑的精细结构与演化

本文对1981年5月8日16h13mUT开始的-N级Hα耀斑进行了图象处理,画出了等光度图。在此基础上,采用二种光度测量法:一是定点法,相对于日面上稳定的定点(～1″),测出50个亮点的位置及其光度变化;另一是亮点跟踪法,测出每一时刻最亮点的位置,看位置的变动。从而得到耀斑的精细结构与演化过程。      

Collaborative VLA,SOHO and RHESSI observations of evolving sources of energy release in the corona above active regions

Very Large Array (VLA) observations at 20 and 91 cm wavelength are compared with data from the SOHO (EIT and MDI) and RHESSI solar missions to investigate the evolution of decimetric Type I noise storms and Type III bursts and related magnetic activity in the photosphere and corona. The combined data sets provide clues about the mechanisms that initiate and sustain the decimetric bursts and about interactions between thermal and nonthermal plasmas at different locations in the solar atmosphere. On one day, frequent, low-level hard X-ray flaring observed by RHESSI appears to have had no clear affect on the evolution of two closely-spaced Type I noise storm sources lying above the target active region. EIT images however, indicate nearly continuous restructuring of the underlying EUV loops which, through accompanying low-level magnetic reconnection, might give rise to nonthermal particles and plasma turbulence that sustain the long-lasting Type I burst emission. On another day, the onset of an impulsive hard X-ray burst and subsequent decimetric burst emission followed the gradual displacement and coalescence of a small patch of magnetic magnetic polarity with a pre-existing area of mixed magnetic polarity. The time delay of the impulsive 20 and 91 cm bursts by up to 20 min suggests that these events were unlikely to represent the main sites of flare electron acceleration, but instead are related to the rearrangement of the coronal magnetic field after the main flare at lower altitude. Although the X-ray flare is associated with the decimetric burst, the brightness and structure of a long-lasting Type I noise storm from the same region was not affected by the flare. This suggests that the reconfiguration of the coronal magnetic fields and the subsequent energy release that gave rise to the impulsive burst emission did not significantly perturb that part of the corona where the noise storm emission was located.     

X-ray plasma ejections and jets from solar compact flares observed with the Yohkoh soft X-ray telescope

Yohkoh soft X-ray observations have revealed coronal X-ray plasma ejections and jets associated with solar flares. We have studied an X-ray plasma ejection on 1993 November 11 in detail, as a typical example of X-ray plasma ejections (possibly plasmoids expected from the reconnection model). The results are as follows: (1) The shape of the ejected material is a loop before it begins to rise. (2) The ejecta are already heated to 5 – 16 MK before rising. (3) The kinetic energy of the ejecta is smaller than the thermal energy content of the ejecta. (4) The thermal energy of the ejecta is smaller than that of the flare regions. (5) The acceleration occurs during the impulsive phase. These results are compared with the characteristics of X-ray jets, and a possible interpretation (for both plasmoids and jets) based on the magnetic reconnection model is briefly discussed.     

Study of combined soft and hard X-ray images of solar flares

We have studied soft and hard X-ray images of 13 solar flares from six active regions observed by the Hard X-ray Imaging Spectrometer (HXIS). Our results indicate the presence of pre-hard X-ray burst excesses in the 11.5–30.0 keV range, indicating a slow buildup of the acceleration process or a strong preheating. During the impulsive phase, all of the events show the simultaneous energization of neighboring field structures, which, in the case we show in some detail, share about equal amounts of the released energy. This association seems to be indicative of strong acceleration and energy release triggered by the interaction between magnetic loops.     

Narrowband dm-spikes in the frequency range above 1 GHz and hard X-ray emission

Narrowband dm-spikes observed in nine intervals during five solar flares in the 1–2 GHz range were analyzed together with the RHESSI and HXRS observations. It was found that the over-frequency integrated radio flux during the spike period is closely related with the hard X-ray bursts (the correlation coefficient was 0.7–0.9) and their time delays after X-rays were 2–14 s, with one exception (March 18, 2003) where the time delay was opposite −15 s. Association of spikes with X-ray spectral characteristics enabled us to divide the spikes into two groups: (a) those observed before the soft X-ray flare maximum and, (b) those observed after this maximum. While for the spikes observed after the flare maximum no systematic spectral characteristics were found, the spikes, observed before the flare maximum were at their beginning associated with relatively hard X-ray spectra and their hardness decreased with time. The RHESSI X-ray sources were compact, only in the March 18, 2003 event an additional X-ray source appeared just at the time of the dm-spikes observation. Fourier transformation of the dynamic spectra of spikes was done to compare their dynamics with the X-ray spectral indices. No correlation between power-law spike and X-ray indices were found. It indicates that the MHD turbulence, if it plays a role, does not represent a strong connection between the spectral characteristics of the dm-spikes and associated X-ray bursts. Furthermore, the results were compared with those obtained by (Aschwanden, M.J., Güdel, M. The coevolution of decimetric millisecond spikes and hard X-ray emission during solar flares. Astrophys. J. 401, 736–753, 1992) for spikes observed on lower radio frequencies. Contrary to their results, no monotonic dependence between time delays and X-ray intensities were found. Finally, the results were discussed using the model of the narrowband dm-spikes and model of electron acceleration in the collapsing magnetic trap.