Multiple-ribbon flares are usually complex in their magnetic topologies and eruption mechanisms. In this paper, we investigate an X2.1 flare (SOL2015-03-11T16:22) that occurred in active region 12297 near the center of the solar disk by both potential and nonlinear force-free field models extrapolated with the data observed by the Helioseismic and Magnetic Imager (HMI) on board Solar Dynamics Observatory (SDO). We calculate the three-dimensional squashing degree distribution. The results reveal that there are two flux ropes in this active region, covered by a large scale hyperbolic flux tube (HFT), which is the intersection of quasi-separatrix layers with a null point embedded in it. When the background magnetic field diminishes due to the separation of the northwest dipole and the flux cancellation, the central flux rope rises up forming the two brightest central ribbons. It then squeezes the upper lying HFT structure to generate further brightenings. This very energetic flare with a complex shape is accompanied by a coronal mass ejection (CME). We adopt the simplified line-tied force-balance equation of the current ring model and assign the observed value of the decay index to the equation to simulate the acceleration profile of the CME in the early stage. It is found that the path with an inclination of $45^\circ$ from radial best fits the profile of the actual acceleration.
Statistical Properties of Ribbon Evolution and Reconnection Electric Fields in Eruptive and Confined Flares
本文对H $α$双带耀斑色球带演化进行了统计研究。该数据集由2000年6月至2015年6月发生的50次局限（$62\,\%$）和喷发（$38\,\%$）耀斑组成。耀斑是均匀地选择在H $α$和$\textit{GOES}$（地球同步业务环境卫星）类，重点是包括强大的封闭耀斑和弱喷发耀斑。Kanzelhöhe天文台的H $α$滤波图与$\textit{MDI}$（迈克尔逊多普勒成像仪）和$\textit{HMI}$（日震和磁成像仪）磁图相结合，用于推导带分离、带分离速度、磁场强度和重联电场。我们发现，爆发耀斑揭示统计更大的带状分离和更高的带状分离速度比密闭耀斑。此外，带状分离的爆发耀斑与GOES SXR通量，而没有明确的依赖被发现为封闭的耀斑。最大的带状分离速度与GOES通量没有相关性，但爆发耀斑揭示了平均更高的带状分离速度（由$\approx 10~$ km $~$ s $^{-1}$）。局限耀斑（$cc=0.50~\pm~0.02$）和爆发耀斑（$cc=0.77~\pm~0.03$）的局部重联电场与GOES通量相关，表明更强大的耀斑涉及更强的重联电场。此外，具有更高电场强度的爆发耀斑往往伴随着更快的日冕物质抛射。
A Two-ribbon White-light Flare Associated with a Failed Solar Eruption Observed by ONSET, SDO, and IRIS
双带增亮是爆发型太阳耀斑最显著的特征之一，常被用来预测日冕物质抛射（CME）的发生。然而，最近有人质疑是否所有的双带耀斑都是爆发性的。在本文中，我们研究了一个两个带状白光（WL）耀斑，这是与失败的磁通量绳（MFR）爆发2015年1月13日，没有伴随CME在WL日冕。\textit{Optical and Near-infrared Solar Eruption Tracer}和\textit{Solar Dynamics Observatory}的观测结果表明，随着耀斑发射的增加和未成功爆发的MFR的加速，在WL 3600的通带处出现了两个孤立的核，并迅速发展成两个细长的带状结构。WL连续谱增强的演化与\textit{Fermi}硬X射线26- 50 keV通量的变化在时间上完全一致。在\textit{Interface Region Imaging Spectrograph}观察到的整个FUV和NUV通带处，连续发射的增加也是清晰可见的。此外，在一个WL核中，\ion{Si}{4}、\ion{C}{2}和\ion{Mg}{2} h/k线显示显著增强和非热增宽。然而，它们的多普勒速度模式是依赖于位置的。在强烈明亮的像素，这些线表现出蓝移;而在中等明亮的，线通常是红移。这些结果表明，失败的MFR爆发也能够产生一个双带耀斑和高能电子，加热低层大气，导致WL和FUV/NUV连续辐射和色球…
Observations of solar flare ribbons show significant fine structure in the form of breaking wave-like perturbations and spirals. The origin of this structure is not well understood, but one possibility is that it is related to the tearing instability in the flare current sheet. Here we study this connection by constructing an analytical three-dimensional magnetic field representative of an erupting flux rope with a flare current sheet below it. We introduce small-scale flux ropes representative of those formed during a tearing instability in the current layer, and use the squashing factor on t…
We studied a circular-ribbon flare, SOL2014-12-17T04:51, with emphasis on its thermal evolution as determined by the Differential Emission Measure (DEM) inversion analysis of the extreme ultraviolet (EUV) images of the Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO). Both temperature and emission measure start to rise much earlier than the flare, along with an eruption and formation of a hot halo over the fan structure. In the main flare phase, another set of ribbons forms inside the circular ribbon, and expands as expected for ribbons at the footpoin…
We analyze high-cadence vector magnetograms (135~s) and flare-ribbon observations of 37 flares from the Solar Dynamics Observatory to understand the spatial and temporal properties of changes in the photospheric vector magnetic field and their relationship to footpoints of reconnected fields. Confirming previous studies, we find that the largest permanent changes in the horizontal field component lie near the polarity inversion line, whereas changes in the vertical field are less pronounced and are distributed throughout the active region. We find that pixels swept up by ribbons do not always …
In this article, we measure the mean magnetic shear from the morphological evolution of flare ribbons, and examine the evolution of flare thermal and non-thermal X-ray emissions during the progress of flare reconnection. We analyze three eruptive flares and three confined flares ranging from GOES class C8.0 to M7.0. They exhibit well-defined two ribbons along the magnetic polarity inversion line (PIL), and have been observed by the Atmospheric Imaging Assembly and the Ramaty High Energy Solar Spectroscopic Imager from the onset of the flare throughout the impulsive phase. The analysis confirms…
Filament Eruption in NOAA 11093 Leading to a Two-Ribbon M1 Class Flare and CME
利用SDO、STEREO、RHESSI和GONG H $α$网络望远镜获得的数据，对2010年8月7日发生在活动区（AR）NOAA 11093的一次喷发事件进行了多波长分析。根据这些观测结果，我们推断，位于极性反转线（PIL）上的反S形暗条的向上缓慢上升运动导致了双带耀斑之后的CME。上覆磁力线穿过灯丝与旁瓣磁力线的相互作用，相关的EUV增亮，以及灯丝周围的通量出现/取消是导致其不稳定和爆发的过程的观测特征。此外，暗条/磁绳的上升运动轮廓与耀斑特征，即，重连率和HXR发射曲线。通量绳在耀斑的峰值阶段加速到最大速度作为CME，然后减速到平均速度为590 km $^{-1}$。我们认为，所观察到的出现/取消附近的灯丝的磁通量导致它上升，导致在系绳切割和重新连接发生在灯丝下，在协议与系绳切割模型。相应的增加/减少，发现在后高峰阶段的爆发的光球通量的正/负提供了明确的证据，重新连接的系绳切割的结果。
Lower atmospheric lines show peculiar profiles at the leading edge of ribbons during solar flares. In particular, increased absorption of the BBSO/GST \hei~10830~Å line \citep[e.g.][]{Xu2016}, as well as broad and centrally reversed profiles in the spectra of the \mgii~and \cii~lines observed by the \iris~satellite \citep[e.g.][]{Panos2018,Panos2021a} have been reported. In this work, we aim to understand the physical origin of the \iris\ ribbon front line profiles, which seem to be common of many, if not all, flares. To achieve this, we quantify the spectral properties of the \iris~\mgii~ribb…
We investigate the onsets of three consecutive coronal mass ejection (CME) eruptions in 12 hours from a large bipolar active region (AR) observed by SDO, STEREO, RHESSI, and GOES. Evidently, the AR initially had a triple-decker configuration: three flux ropes in a vertical stack above the polarity inversion line (PIL). Upon being bumped by a confined eruption of the middle flux rope, the top flux rope erupts to make the first CME and its accompanying AR-spanning flare arcade rooted in a far-apart pair of flare ribbons. The second CME is made by eruption of the previously-arrested middle flux r…
Flare Ribbons Approach Observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory
我们报告了2015年11月4日在NOAA AR 12443中的多带M级耀斑期间的耀斑带接近（FRA），由界面区域成像光谱仪和太阳动力学观测台获得。耀斑由一对主带和两对次带组成。这两对次级带的形成晚于主带的出现，分别延迟了15分钟和19分钟。负极性的主带比在其前面的具有相同极性的第一次级带更快地向外扩展，因此产生了FRA。就在他们相遇之前，主带急剧变暗，其强度在2分钟内下降了约70%，这意味着产生两个主带的主相重联被抑制。FRA导致主带向副带方向偏转，偏转角约为60度。大约2分钟后形成了后接近拱廊，并沿新拱廊检测到速度为35-40 km/s的下降流，表明FRA过程中的磁重组。我们认为，有三个拓扑结构域的足迹概述的三对丝带。这些域的紧密接近导致与磁场拓扑一致的带的偏转。
How filaments form and erupt are topics about which solar researchers have wondered since more than a century and that are still open to debate. We present observations of a filament formation, its failed eruption, and the associated flare (SOL2019-05-09T05:51) that occurred in active region (AR) 12740 using data from SDO, STEREO-A, IRIS, and NSO/GONG. AR 12740 was a decaying region formed by a very disperse following polarity and a strong leading spot, surrounded by a highly dynamic zone where moving magnetic features (MMFs) were seen constantly diverging from the spot. Our analysis indicates…
Automatic detection of Flare Ribbon Fine Structures as Proxies for Plasmoid Dynamics in Flare Reconnection
Department of Mathematical Sciences, Durham University（达勒姆大学数学科学系）；Heliophysics Science Division, NASA Goddard Space Flight Center（NASA戈达德太空飞行中心日球物理学部）；Astronomy Department, University of Maryland, College Park（马里兰大学天文学系）；Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow（格拉斯哥大学物理与天文学学院苏格兰大学物理联盟）；Rosseland Centre for Solar Physics, University of Oslo（奥斯陆大学罗瑟兰太阳物理学中心）
A Data-constrained Magnetohydrodynamic Simulation of Successive X-class Flares in Solar Active Region 13842 I. Dynamics of the Solar Eruption Associated with the X7.1 Solar Flare
We report multi-wavelength study of a complex M-class solar eruptive flare that consists of three different sets of flare ribbons, viz. circular, parallel, and remote ribbons. Magnetic field modeling of source active region NOAA 12242 exhibits the presence of 3D null-point magnetic topology which encompasses an inner bipolar region. The event initiates with the faint signatures of the circular ribbon along with remote brightening right from the pre-flare phase which points toward the ongoing slow yet persistent null-point reconnection. We first detected flux cancellation and an associated brig…
We present the analysis of three kinds of oscillating behavior using multi-wavelength observations of the 10 November 2013 (SOL2013-11-10T05:14) circular-ribbon flare. This event is a typical circular-ribbon flare with an outer spine structure and homologous jets. We found three kinds of oscillations (or perturbations): i) flux oscillation (or QPP) with a dominant period of about 20 seconds in X-ray, EUV, and microwave emissions, ii) periodic jets with an intermittent cadence of around 72 seconds, iii) an outer loop perturbing half a cycle with a duration of about 168 seconds. Similar to the p…
This paper studies the magnetic topology of successively erupting active regions (ARs) 11429 and 12371. Employing vector magnetic field observations from Helioseismic and Magnetic Imager, the pre-eruptive magnetic structure is reconstructed by a model of non-linear force-free field (NLFFF). For all the five CMEs from these ARs, the pre-eruptive magnetic structure identifies an inverse-S sigmoid consistent with the coronal plasma tracers in EUV observations. In all the eruption cases, the quasi-separatrix layers (QSLs) of Large Q values are continuously enclosing core field bipolar regions in w…
Study of Two Successive Three-Ribbon Solar Flares on 2012 July 6
这封信报告了2012年7月6日在NOAA AR 11515中观察到的两个罕见的三带耀斑（M1.9和C9.2），我们用新太阳望远镜的0.1”分辨率的Halpha观测和Hinode的CaII H图像发现了这两个耀斑。耀斑网站的特点是一个有趣的“鱼骨状”的形态证明了这两个Halpha图像和非线性无力场（NLFFF）外推，其中两个半平行行的低洼，剪切环连接一个细长的，寄生的负场与寄生的正场。NLFFF模型还表明，这两排环的高度是不对称的，有相反的扭曲，并被大规模的磁力线，包括开放的领域。两次耀斑在半小时内相继发生，位于耀斑区的两端。每个耀斑的三个带状物平行于PIL，外部两个位于正磁场中，中心一个位于负磁场中。这两个耀斑都显示出明显朝向偏远地区的Halpha浪涌流，而C9.2耀斑也伴随着EUV喷流，可能沿着开放场线。有趣的是，C9.2耀斑的12-25 keV硬X射线源首先与中央带状物对齐，然后转移到集中在环的较高分支的顶部。这些结果进行了讨论有利于重联沿日冕零线产生的三个耀斑带和相关的喷射。
