AR2522活动区中暗条的演化与耀斑的爆发

利用ＡＲ２５２２活动区多波段的观测资料，分析了暗条演化与１Ｂ／Ｍ４级双带耀斑爆发之间的关系。结果表明：（１）足点的剪切运动导致暗条电流增强和耀斑贮能；（２）暗条上升运动和绞扭现象是单产要电流增强和耀斑贮能的结果；（３）Ｍａｒｔｔｅｎｓ－Ｋｕｉｎ模型至少适合于解释与暗条快速上升有关的双带耀斑爆发。     

2011年8月4日螺旋状日冕物质抛射爆发事件

利用多卫星多波段的综合观测数据，通过追踪光球表面等离子体速度分析计算了耀斑爆发前后磁螺度的变化，发现耀斑爆发前活动区中光球表面存在强的水平剪切运动，活动区磁螺度的注入主要由这种剪切运动所产生；使用CESE-MHD-NLFFF重建了耀斑爆发前后活动区的磁场位形，推测出耀斑过程中存在磁绳结构的抛射.基于这些分析，给出了这一螺旋状抛射结构的形成机制:爆发前暗条西侧足点的持续剪切运动驱动磁通量绳增加扭转，高度扭缠的通量绳与东侧足点附近的开放磁力线重联并与东侧足点断开，进而向外抛出并伴随解螺旋运动.另外，利用1AU处WIND卫星的观测数据在对应的行星际日冕物质抛射中找到典型磁云的观测特征.这表明除了传统上双足点均在太阳表面的磁云模型，这种单足点固定于太阳表面的磁通量绳爆发图景同样可能在行星系际空间形成磁云结构.研究结果对进一步认识磁云结构具有重要意义.      

暗条电流演化和耀斑储能

利用紫金山天文台观测的编号为McMath8207和McMath16171两个活动区光学资料，采用KR和KS两种理论模型，计算了活动区暗条电流演化过程.结果表明：不同的暗条扰动可以导致不同类型的耀斑;出现在强活动区新浮磁流附近的拱状暗条可用KR模型描述，它们往往处于较低层次，具有较强的初始电流，在新浮磁流的挤压和剪切作用下可形成中性电流片，导致高能耀斑发生.而符合KS模型的宁静暗条，在新浮磁流或耀斑波作用下亦可被激活，但其初始电流较弱，往往只能为热耀斑提供能量.     

太阳X射线耀斑活动区的一些特征

对ISEE-3人造卫星在1980年5月—1981年8月中,观测到的48个X射线耀斑进行了分析,发现其中有1/3是在6个活动区中重复爆发的.研究这部分X射线耀斑的物理性质与所在活动区的黑子面积、活动区类型及磁结构的关系,得到了一些结果:(1)发生在同一活动区中的X射线耀斑,其硬X射线峰值积分流量及谱硬度与活动区黑子面积成正相关;(2)多次爆发X射线耀斑的活动区全部具有δ型磁结构;(3)发生在不同活动区中的X射线耀斑,其物理特征与所在活动区的面积大小无明显关系.由此可以认为,活动区磁场梯度的大小,亦即活动区电流的大小,在爆发耀斑的过程中具有决定性作用.此外,还用电流环模型从理论上讨论了上述特征.     

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.     

22太阳活动周的δ黑子群与X级X射线耀斑

用２２太阳活动周的２２１个δ黑子群（从１９８６年至１９９１年），研究δ黑子群的特性，δ黑子群与Ｘ级Ｘ射线耀斑（ＸＸＦ）之间的关系。１．证实了Ｔａｎｇ，Ｚｉｒｉｎ和Ｌｉｇｇｅｔｔ的发现，所有δ黑子群源于二个偶极黑子区，由其中之一的前导黑子与另一的后随黑子相互渗透而构成；在δ黑子的极性分界线上，磁场是强烈地剪切的，同时还找到了许多δ黑子解体的事例，这点与Ｚｉｒｉｎ（１９８７）的结论相悖，δ黑子的解体是     

硬X射线爆发的Hα特征

对50个Ha耀斑检查表明:1.有硬X射线爆发(HXRBS)的耀斑,其Ha的线宽均超过4A,HXRBS对应的Ha耀斑核(在Ha 2A处,J_(耀斑核)/I_(背景)≥1.15)至少有两个,它们分处于磁场正负极性区;2.Ha耀斑开始较早, Ha耀斑核(kernel)的强度峰落后HXRBS的峰(spike)数秒,峰与峰之间有很好的对应关系; 3.Ha耀斑核,当HXRBS峰值计数率大于1000时,掩盖黑子半影,峰值计数率小于200时,不掩盖黑子半影。     

同无黑子耀斑相协的微波爆发机制的探讨

1980—1984年期间,我们在云南天文台9375MHz,3653MHz和2902 HHz三个波段的射电观测资料中,查到11组微波爆发与无黑子耀斑相伴随。本文研究了这些爆发与耀斑的大气层高度,射电爆发类型以及通过落进峰值流量-时间图的位置,确认出爆发机制是活动区中作麦克斯韦分布电子的热轫致辐射。     

利用MF雷达对耀斑期间电离层D区电子密度的观测研究

利用MF雷达观测资料对X级别耀斑爆发期间在66-80km高度之间的电子密度进行了研究，观测到了耀斑爆发期间电子密度的突然增加，在较低高度上的电子密度的时间变化趋势与耀斑的软X射线辐射通量相关．电子密度的变化强度依赖于具体的耀斑参数，有些耀斑引起的电子密度增加高达400cm^-3，有些仅为100cm^-3左右．但耀斑期间在这一高度区间增加的总电子含量增量仅占耀斑辐射引起的整个电离层总电子含量增量的千分之一左右．最后，利用恢复阶段电子密度的时间变化过程估算了1997年11月4日耀斑期间部分高度上的有效复合系数．     

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.      

Preflare heating of filaments

Disappearances of preflare filaments have been observed on June 22, 1980 (S07,W13) (flare at 13.04 U.T.) and September 3, 1980 (flare at 7.52 U.T.). The analysis of MSDP data (MEUDON) leads to the followings conclusions : - Disappearances begin a few minutes before the Hα impulsive phase. - The filaments can be seen again after the flares. - Upwards motions occur in several points, without disturbing significantly preëxisting downflows.Velocity maps suggest shears or velocity loops.The filament disappearance seems to be due to a heating mechanism beginning before the flare maximum.     

Relationships of a growing magnetic flux region to flares

Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic flux region within a complex of active regions, Hale No. 16918. This analysis was done as a part of a continuing study of the circumstances associated with flares in Hale Region 16918, which was designated as an FBS target during the interval 18 – 23 June 1980. We studied the initiation and development of both major and minor flares in Hα images in relation to the identified potential flare sites at the boundaries of the growing flux region and to the general development of the new flux. This study lead to our recognition of a spectrum of possible relationships of growing flux regions to flares as follows: (1) intimate interaction with adjacent old flux — flare sites centered at new/old flux boundary, (2) forced or “intimidated” interaction in which new flux pushes old field having lower flux density towards a neighboring old polarity inversion line where a flare then takes place, (3) “influential” interaction — magnetic lines of force over an old polarity inversion line, typically containing a filament, reconnect to the new emerging flux; a flare occurs with erupting filament when the magnetic field overlying the filament becomes too weak to prevent its eruption, (4) inconsequential interaction — new flux region is too small or has wrong orientation for creating flare conditions, (5) incidental — flare occurs without any significant relationship to new flux regions.     

Detailed analysis of dynamic evolution of three Active Regions at the photospheric level before flare and CME occurrence

We present a combined analysis of the applications of the weighted horizontal magnetic gradient (denoted as ${\mathit{WG}}_M$ in Korsós et al. (2015)) method and the magnetic helicity tool (Berger and Field, 1984) employed for three active regions (ARs), namely NOAA AR 11261, AR 11283 and AR 11429. We analysed the time series of photospheric data from the Solar Dynamics Observatory taken between August 2011 and March 2012. During this period the three ARs produced a series of flares (eight M- and six X-class) and coronal mass ejections (CMEs). AR 11261 had four M-class flares and one of them was accompanied by a fast CME. AR 11283 had similar activities with two M- and two X-class flares, but only with a slow CME. Finally, AR 11429 was the most powerful of the three ARs as it hosted five compact and large solar flare and CME eruptions. For applying the ${\mathit{WG}}_M$ method we employed the Debrecen sunspot data catalogue, and, for estimating the magnetic helicity at photospheric level we used the Space-weather HMI Active Region Patches (SHARP’s) vector magnetograms from SDO/HMI (Solar Dynamics Observatory/Helioseismic and Magnetic Imager). We followed the evolution of the components of the ${\mathit{WG}}_M$ and the magnetic helicity before the flare and CME occurrences. We found a unique and mutually shared behaviour, called the U-shaped pattern, of the weighted distance component of ${\mathit{WG}}_M$ and of the shearing component of the helicity flux before the flare and CME eruptions. This common pattern is associated with the decreasing-receding phases yet reported only known to be a necessary feature prior to solar flare eruption(s) but found now at the same time in the evolution of the shearing helicity flux. This result leads to the conclusions that (i) the shearing motion of photospheric magnetic field may be a key driver for solar eruption in addition to the flux emerging process, and that (ii) the found decreasing-approaching pattern in the evolution of shearing helicity flux may be another precursor indicator for improving the forecasting of solar eruptions.     

A study of a long duration B9 flare-CME event and associated shock

We present and discuss here the observations of a small long duration GOES B-class flare associated with a quiescent filament eruption, a global EUV wave and a CME on 2011 May 11. The event was well observed by the Solar Dynamics Observatory (SDO), GONG H$\alpha$, STEREO and Culgoora spectrograph. As the filament erupted, ahead of the filament we observed the propagation of EIT wave fronts, as well as two flare ribbons on both sides of the polarity inversion line (PIL) on the solar surface. The observations show the co-existence of two types of EUV waves, i.e., a fast and a slow one. A type II radio burst with up to the third harmonic component was also associated with this event. The evolution of photospheric magnetic field showed flux emergence and cancellation at the filament site before its eruption.     

The magnetohydrodynamic development of two-ribbon flares or a five-finger theory for solar flares

A semi-analytical model for the electrodynamic development of two-ribbon flares is presented. A current filament above a bipolar active region starts rising according to the model of Van Tend and Kuperus. Due to this motion large induced electric fields arise at a magnetic neutral line far below the filament, resulting in and associated with magnetic reconnection and the formation of a current sheet. The interaction of this current sheet with the original current filament, the background magnetic field and the boundary layer of the photosphere determine the further electrodynamic development of the flare. The model predicts the energy release, the time of maximum, the height of the energy source and other quantities reasonably well.     

Energy release and transport in arcade flares

This work is based on hard and soft X-ray observations from the YOHKOH satellite. We investigate an example of an arcade flare, for which the arcade channel is seen in soft X-rays as a long bright filament. We have found that:

1. (1) Energy can efficiently flow along the arcade channel from the very beginning of a flare.

2. (2) During flare evolution a few kernels of hard X-ray emission develop along the arcade channel. Clearly, they are new, additional sources of the flare energy release. A probable scheme of formation of such hard X-ray kernels is briefly discussed.

     

AR5395活动区演化的周期性

观测资料分析表明,AR5395活动区演化具有周期性的特征,软X射线峰值流量F变化周期为24.3小时,X射线耀斑出现率N_x,具有12.2小时的周期性,活动区黑子群面积S_x的变化呈现24.4小时的周期。这3个周期变化量的相位关系表明:(1)X级耀斑往往发生在黑子面积减小的位相;(2)在1个周期内,黑子群面积达到最大值约需16小时,恢复到大耀斑前水平约需8小时;(3)在X级大耀斑前约12小时,小级别耀斑出现率达到峰值。分析显示,AR5395活动区似乎工作于大耀斑能量储存—释放—储存周期性循环的极限状态之中。     

Converging motion of conjugate flaring kernels during two large solar flares

In this paper, we analyze the footpoint motion of two large solar flares using observations made by the Transition Region and Coronal Explorer (TRACE) and Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The two flares are the M5.7 flare of March 14, 2002 and the X10 flare of October 29, 2003. They are both classical two-ribbon flares as observed in TRACE 1600 or 171 Å images and have long-duration conjugate hard X-ray (HXR) footpoint emission. We use the ‘center-of-mass’ method to locate the centroids of the UV/EUV flare ribbons. The results are: (1) The conjugate UV/EUV ribbons and HXR footpoints of the two flares show a converging (inward) motion during the impulsive phase. For the two flares, the converging motion lasts about 3 and 10 min, respectively. The usual separation (outward) motion for the flare ribbons and footpoints take place only after the converging motion. (2) During the inward and the outward motion, the conjugate ribbons and footpoints of the two events exhibit a strong unshear motion. In obtaining above results, TRACE UV/EUV and RHESSI HXR data show an overall agreement. The two events demonstrate that the magnetic reconnection for the flares occurs in highly sheared magnetic field. Furthermore, the results support the magnetic model constructed by Ji et al. [Ji, H., Huang, G., Wang, H. Astrophys. J. 660, 893–900, 2007], who proposed that the contracting motion of flaring loops is the signature of the relaxation of sheared magnetic fields.