共查询到20条相似文献，搜索用时 140 毫秒
1.
通过对活动区ＮＯＡＡ６８９１中三个Ｘ线耀斑前后的向量磁场分析,研究耀斑发生条件与耀斑发生前后横向磁场和磁剪切变化的关系。我们发现与Ｈａｇｙａｒｄ的耀斑发生条件不同的是,强的横向磁场和磁剪切不是活动区中耀斑发生的充要条件。我们的结果表明,活动区ＮＯＡＡ６８９１ １９９１年３０日的耀斑发生在横向磁场和磁剪切剧烈下降后。尽管１０月２７日的耀斑发生后横向磁场和磁剪切变化很大,但由于有新磁流浮现,造成磁中性 相似文献
2.
1989年1月14日AR5312(怀柔编号89009)活动区,产生了一个2B级耀斑。该活动区经纬度为L306、S32,黑子群磁场分类为δ型。耀斑开始时间为0202UT,结束为0534UT,持续了3个多小时。北京天文台磁场望远镜,得到了一系列较完整的高分辨磁场及速度场资料,包括光球5324A的矢量磁场图和色球4861A的纵向磁场图(图1、2)。从耀斑前后的磁图得到以下结果: 1、耀斑初始亮点位于纵向磁场中性线附近高度剪切区域(见图1B区)、新浮磁流区(图2D区)以及双极磁结构对消区。前两种区域均能形成电流片,并且引起磁流体不稳定性,从而激发耀斑,但对消区和耀斑的关系不是很清楚,有待于理论工作者进一步探讨。 2、耀斑极大时间过后,光球和色球H_(11)=0线附近纵场梯度均有明显下降。 3、在强剪切区域(图1B区),5324A横向磁场和H_(11)=0线之间的夹角在耀斑极大时间过后有明显增大,该现象表明磁能释放后,磁场剪切缓解。 4、耀斑初始亮点产生后磁场高度剪切区、新浮磁流区和双极对消区,其触发耀斑的作用和周围的磁场环境有密切关系,特别是象具有磁海湾结构这样的活动区,似乎更容易产生耀斑。 5. 该活动区色球磁场位形,较光球磁场位形复杂,主要表现在:色球的纵场出现了一些磁弧岛结构,其原因可能是光球之上的磁力线高度剪切区及扭绞所致。0411 相似文献
3.
4.
本文描述ＮＯＡＡ６２３３活动区中的一组双带耀斑及和与之有时间相关性的ＮＯＡＡ６２４０中的单带耀斑的磁场位形．并着重讨论由观测推断出的磁场拓扑联接性．分析表明：三个单耀斑发生在正极磁区里，与发生在δ黑子区中的双带耀斑，可能有远距离磁环相联系．这一高位磁环与δ黑子中的低位剪切磁环柑互作用，可能是能发双带耀斑的直接原因．在双带耀斑能量初始释放中被加速的电子，可能是沿着高位磁环或磁拓扑分界面（ＮＯＡＡ ６２４０与ＮＯＡＡ６２３３间）传播，并导致ＮＯＡＡ６２４０中的单带耀斑．因此这些单带耀斑都可能是双带耀斑的相应耀斑． 相似文献
5.
通过对活动区NOAA 6891中三个X级耀斑前后的向量磁场分析 ,研究耀斑发生条件与耀斑发生前后横向磁场和磁剪切变化的关系。我们发现与Hagyard的耀斑发生条件不同的是 ,强的横向磁场和磁剪切不是活动区中耀斑发生的充要条件。我们的结果表明 ,活动区NOAA 6891 1 991年 30日的耀斑发生在横向磁场和磁剪切剧烈下降后。尽管 1 0月 2 7日的耀斑发生后横向磁场和磁剪切变化很大 ,但由于有新磁流浮现 ,造成磁中性线的改变 ,使得横向磁场和磁剪切变化与耀斑发生的联系变得比较复杂。 相似文献
6.
本文分析了云台78126活动区的五天的磁场等高斯图资料后得出,倒置的磁极性排列和纵场中性线变得迂回曲折与高能质子耀斑爆发紧密相关。在耀斑爆发后,无论是磁极性排列和纵场中性线都趋于相对稳定状态。我们发现,活动区的净磁通量φ在4月28—30日期间有急剧的变化,而在这期间发生了二个重大耀斑。我们猜想,可能是磁通量的迅速变化引起的强大电动势造成了电子和质子加速的条件。分析了耀斑结点在磁图中的分布后得出;本活动区的耀斑亮点大多数离中性线区域较远,而出现在中性线附近的亮结点,可以大致分为两种情形,一种是在中性线两侧的磁场梯度很大且具有相反电流密度的区域;另一种是出现在磁场的“中性点”附近。 相似文献
7.
本文利用紫金山天文台太阳光谱仪缝前附属Ｄａｙｓｔａｒ滤光器拍摄的，发生在ＮＯＡＡ５３９５活动区中的三个耀斑的Ｈα单色光资料，对比北京天文台怀柔观测站取得的光球磁场资料，研究耀斑产生位置与光球磁场演化的关系，结果表明：（１）在所研究的５０个耀斑亮核中，有３８个位于新浮磁流区附近，另有少数亮核出现在磁对消区；（２）耀斑亮核多集中在横场方向交叉，剪切角大的复杂磁区，耀斑后多数区域磁场结构简化；（３）耀斑 相似文献
8.
用我国第一台高分辨光球——色球望远镜所取得的AR4811的高空间分辨(≤1″)的黑子和Hα色球照相资料分析了该活动区的精细结构的演化特征及有关耀斑活动。指出:(1)和当地原有磁场极性相同的新磁流的浮现在黑子群演化过程中起着阶段性的重要作用,但对活动区耀斑活动贡献不大。(2)有关暗条的各种频繁活动是当地耀斑的一种先兆。(3)活动区中相反极性磁场的相互挤压、剪切和旋转同时存在,是一个2B/M1.3级等一系列耀斑可能的储能机制。而与当地原有磁场极性相反的磁流环的浮现,是2B/M1.3级耀斑的可能触发因素。 相似文献
9.
当太阳黑子磁环从太阳对流层深层上浮到太阳表面时,便形成了一个双极黑子群的活动区。在活动区内,纵向磁场为零的中性线区域为高压区,垂直向上气流把黑子磁弧吹入日冕。同时在磁弧的顶部,即在中性线上空产生了感应电流,它的焦耳耗散形成了H_α耀斑。然而,因两个黑子区内为低压区,吸注气流从黑子磁弧的两条腿部顺磁力线流向黑子,它与位于中性线的上升气流形成了两个对称环流,随着环流和磁弧的发展,耀斑区向中性线两旁分离,因而呈现出双带耀斑的特征。本文还估计了耀斑的能量,只要横越磁场的速度,v_⊥～0.3—3公里。秒~(-1),磁场强度B～10—100高斯,这就足以产生耀斑所需要的10~(29)～10~(33)尔格的能量。 相似文献
10.
用势场方法和格林函数解构造了三维日冕磁场.相关的边界条件是所观测的光球磁场以及光球上2.6个太阳半径的开放场(源表面).所用的光球数据来自高精度的MDI/SOHO观测(2″/像素,1桢/98min).这种外推方法可以用来分析太阳大事件在大尺度上的可能触发机制.作为一个例子,我们分析了活动区NOAA9077的外推日冕场,发现它们的形态与EIT/SOHO的日冕观测相符很好.结合全日面Hα演化,我们推测来自活动区9082的一次激波扰动应该是导致2000年7月14日大耀斑和日冕物质抛射的触发原因,该扰动沿着外推所得到的一个磁环系统直接传到大耀斑爆发位置. 相似文献
11.
In this paper, we reconstruct the finite energy force-free magnetic field of the active region NOAA 8100 on 4 November 1997
above the photosphere. In particular, the 3-D magnetic field structures before and after a 2B/X2 flare at 05:58 UT in this
region are analyzed. The magnetic field lines were extrapolated in close coincidence with the Yohkoh soft X-ray (SXR) loops accordingly. It is found that the active region is composed of an emerging flux loop, a complex loop
system with differential magnetic field shear, and large-scale, or open field lines. Similar magnetic connectivity has been
obtained for both instants but apparent changes of the twisting situations of the calculated magnetic field lines can be observed
that properly align with the corresponding SXR coronal loops. We conclude that this flare was triggered by the interaction
of an emerging flux loop and a large loop system with differential magnetic field shear, as well as large-scale, or open field
lines. The onset of the flare was at the common footpoints of several interacting magnetic loops and confined near the footpoints
of the emerging flux loop. The sheared configuration remained even after the energetic flare, as demonstrated by calculated
values of the twist for the loop system, which means that the active region was relaxed to a lower energy state but not completely
to the minimum energy state (two days later another X-class flare occurred in this region). 相似文献
12.
Numerical three-dimensional MHD simulations demonstrated that a current sheet (CS) was formed over active region AR 0365 before the flare of May 27, 2003, and the energy was accumulated in its magnetic field. Maps of the photospheric magnetic field in its preflare state were used in the simulations to define the boundary conditions instead of the usually applied approximation of the field in an active region by dipoles or magnetic charges. The CS was formed in the vicinity of a singular line as a result of focusing the magnetic field disturbances observed before the flare. The calculated CS position corresponded to the maximum brightness temperature of the flare detected by the Siberian Solar Radio Telescope SSRT (Institute of Solar-Terrestrial Physics, Russian Academy of Sciences, Siberian Branch, Irkutsk). This testifies that the flare could result from the dissipation of energy accumulated in the field of the CS, which arose over the active region. 相似文献
13.
A C6.0 GOES X-ray-class flare which occurred at 05:32 UT on 5 September 1994 in the active region NOAA 7773 is analyzed in this paper. We found that this flare was triggered by the interaction of a small loop and a large loop. The small loop connected a decaying magnetic flux, not an emergence of magnetic flux as usually shown. These two loops were matched well by the extrapolated force-free field lines based on the Boundary Element Method and the boundary condition of the observed photospheric vector magnetic field. Soft X-ray observation showed that these two loops gradually merged to become one, and the soft X-ray intensity increased during the merging process, agreeing with the simulated results of I-type coalescence derived by Fushiki and Sakai (1995) and Sakai and Fushiki (1995). 相似文献
14.
15.
A topological model with magnetic reconnection at two separators in the corona is used to account for the recently discovered changes of the photospheric magnetic field in the active region NOAA 9077 during the July 14, 2000 flare. The model self-consistently explains the following observed effects: (1) the magnetic field strength decreases on the periphery of the active region but increases in its inner part near the neutral line of the photospheric magnetic field; (2) the center-of-mass positions of the fields of opposite (northern and southern) polarities converge; and (3) the magnetic flux of the active region decreases after the flare. The topological model gives not only a qualitative interpretation of the flare phenomena (the structure of the interacting magnetic fluxes in the corona, the location of the energy sources, the shape of the flare ribbons and kernels in the chromosphere and photosphere), but also correct quantitative estimates of the large-scale processes that form the basis for solar flares. The electric field emerging in the flare during large-scale reconnection is calculated. The electric field strength correlates with the observed intensity of the hard X-ray bremsstrahlung, suggesting an electron acceleration as a result of reconnection. 相似文献
16.
AR5395及AR6659的贮能释能周期性 总被引：1，自引：0，他引：1
本文分析了了AR5395和AR6659的X射线耀斑活动周期性，耀斑强度周期的存在表明活动区的能量积累和释放过程具有可重复性，包括贮存的能量大小也具可重复性，计算得出AR5395的耀风强度周期为24．49小时，而AR6659的周期为57．39小时，耀斑指数按周期的分布证明在一个贮能周期中活动区贮存的能量大致相同，周期内的平均耀斑指数代表能量积累效率，AR6659较之AR5395有较长的能量积累周期和较高的能量积累效率．此外，本文还讨论了耀斑事件出现的周期．这种周期的长短代表活动区磁结构对于耀斑出现的稳定程度，并且，当活动区处于较高能量状态（即相对势场状态的偏离较大）时，出现耀斑不稳定性的可能性增加。 相似文献
17.
Evidence for prolonged acceleration based on a detailed analysis of the long-duration solar gamma-ray flare of June 15, 1991 总被引：2，自引：0，他引：2
V. V. Akimov P. Ambrož A. V. Belov A. Berlicki I. M. Chertok M. Karlický V. G. Kurt N. G. Leikov Yu. E. Litvinenko A. Magun A. Minko-Wasiluk B. Rompolt B. V. Somov 《Solar physics》1996,166(1):107-134
Gamma-ray emission extending to energies greater than 2 GeV and lasting at least for two hours as well as 0.8–8.1 MeV nuclear line emission lasting 40 min were observed with very sensitive telescopes aboard the GAMMA and CGRO satellites for the well-developed post-flare loop formation phase of the 3B/X12 flare on June 15, 1991. We undertook an analysis of optical, radio, cosmic-ray, and other data in order to identify the origin of the energetic particles producing these unusual gamma-ray emissions. The analysis yields evidence that the gamma-rays and other emissions, observed well after the impulsive phase of the flare, appear to be initiated by prolonged nonstationary particle acceleration directly during the late phase of the flare rather than by a long-term trapping of energetic electrons and protons accelerated at the onset of the flare. We argue that such an acceleration, including the acceleration of protons up to GeV energies, can be caused by a prolonged post-eruptive energy release following a coronal mass ejection (CME), when the magnetic field above the active region, strongly disturbed by the CME eruption, relaxes to its initial state through magnetic reconnection in the coronal vertical current sheet. 相似文献
18.
A. M. Uralov V. V. Grechnev G. V. Rudenko I. G. Rudenko H. Nakajima 《Solar physics》2008,249(2):315-335
Neutral Line associated Sources (NLSs) are quasi-stationary microwave sources projected onto vicinities of the neutral line
of the photospheric magnetic field. NLSs are often precursors of powerful flares, but their nature is unclear. We endeavor
to reveal the structure of an NLS and to analyze a physical connection between such a source with a site of energy release
in the corona above NOAA 10488 (October/November 2003). Evolution of this AR includes emergence and collision of two bipolar
magnetic structures, rise of the main magnetic separator, and the appearance of an NLS underneath. The NLS appears at a contact
site of colliding sunspots, whose relative motion goes on, resulting in a large shear along a tangent. Then the nascent NLS
becomes the main source of microwave fluctuations in the AR. The NLS emission at 17 GHz is dominated by either footpoints
or the top of a loop-like structure, an NLS loop, which connects two colliding sunspots. During a considerable amount of time,
the emission dominates over that footpoint of the NLS loop, where the magnetic field is stronger. At that time, the NLS resembles
a usual sunspot–associated radio source, whose brightness center is displaced towards the periphery of a sunspot. Microwave
emission of an X2.7 flare is mainly concentrated in an ascending flare loop, initially coinciding with the NLS loop. The top
of this loop is located at the base of a non-uniform bar-like structure visible in soft X-rays and at 34 GHz at the flare
onset. We reveal i) upward lengthening of this bar before the flare onset, ii) the motion of the top of an apparently ascending flare loop along the axis of this bar, and iii) a non-thermal microwave source, whose descent along the bar was associated with the launching of a coronal ejection. We
connect the bar with a probable position of a nearly vertical diffusion region, a site of maximal energy release inside an
extended pre-flare current sheet. The top of the NLS loop is located at the bottom of this region. A combination of the NLS
loop and diffusion region constitutes the skeleton of a quasi-stationary microwave NLS. 相似文献
19.
1986年2月4日太阳耀斑的演化研究 总被引：1，自引：0，他引：1
本文根据乌鲁木齐天文站的H_α耀斑及3.2cm射电流量观侧资料、云南天文台的黑子精细结构照相和Marshall Space Flight Center的向量磁场图,对1986年2月4日的六个耀斑的形态相关及演化联系,特别是0736UT 4B/3X大耀斑的发展过程进行了综合分析。主要结果是: 1.4日大耀斑的初始亮点和闪光相的主要形态演化,与活动区中沿中性线新浮现的强大电流/磁环系密切相关。后者的主要标志是沿中性线的长的剪切半影纤维及它两端的偶极旋涡黑子群(1_3F_3)。 2.上述大耀斑与1972年8月4日0624 UT大耀斑爆发的磁场背景及主要形态特征相似,表明两者的储能和触发机制可能相同。 3.大耀斑爆发的H_α初始亮点,双带出现,环系形成,亮物质抛射和吸收冕珥等现象同3.2cm射电流量的变化在时间上有较好的对应关系。 4.重复性的前期小耀斑爆发位置和发展趋势与大耀斑的主要形态及演化特征相似。它们相对于剪切的纵场中性线两侧的位置相近或相同。因而,可以看作上述强大电流/磁环系不稳性发展过程中的前置小爆发。 相似文献
20.
Relationship between the geoefficiency of the solar flares as well as of the active regions passing the central meridian of the Sun and the configuration of the large scale solar magnetic field is studied.It is shown that if the tangential component of the large scale magnetic field at the active region or at the flare region is directed southwards, that region and that flare produce geomagnetic storm. In case when the tangential magnetic field is directed northward, the active region and the flares occurring at that region do not cause any geomagnetic disturbance.An index of the geoefficiency of the solar flares and of the active regions is proposed. 相似文献