利用H $α$、He I 10830、EUV和软X射线（SXR）数据，对2006年1月12日发生在太阳盘中心附近的一次暗条爆发进行了观测，该爆发扰动了$\emph{GOES-12}$ SXR成像仪（SXI）观测到的暗条通道上的一个S形通道，导致了该通道的爆发。该事件与太阳和日光层天文台（$\emph{SOHO}$）上的大角度和光谱日冕仪（LASCO）观测到的部分晕日冕物质抛射（CME）有关，并导致形成两个耀斑状条带，爆发后日冕环和两个瞬态日冕洞（TCH），但没有明显记录到与爆发相对应的$\emph{GOES}$或H $α$耀斑。这两个TCHs由相反的磁极性主导，位于喷发的乙状结肠的两端。它们在He I 10830、EUV和SXR观测中显示出相似的位置和形状。在早期喷发阶段，增亮首先出现在两个后续的TCH的位置，这可以清楚地识别在He I 10830，EUV和SXR图像。这一喷发事件可以用磁通量绳模型来解释，而两个TCH很可能是磁通绳的脚。
英文摘要：
By using H$α$, He I 10830, EUV and soft X-ray (SXR) data, we examined a filament eruption that occurred on a quiet-sun region near the center of the solar disk on 2006 January 12, which disturbed a sigmoid overlying the filament channel observed by the $\emph{GOES-12}$ SXR Imager (SXI), and led to the eruption of the sigmoid. The event was associated with a partial halo coronal mass ejection (CME) observed by the Large Angle and Spectrometric Coronagraphs (LASCO) on board the Solar and Heliospheric Observatory ($\emph{SOHO}$), and resulted in the formation of two flare-like ribbons, post-eruption coronal loops, and two transient coronal holes (TCHs), but there were no significantly recorded $\emph{GOES}$ or H$α$ flares corresponding to the eruption. The two TCHs were dominated by opposite magnetic polarities and were located on the two ends of the eruptive sigmoid. They showed similar locations and shapes in He I 10830, EUV and SXR observations. During the early eruption phase, brightenings first appeared on the locations of the two subsequent TCHs, which could be clearly identified on He I 10830, EUV and SXR images. This eruption event could be explained by the magnetic flux rope model, and the two TCHs were likely to be the feet of the flux rope.
Sympathetic eruptions of two solar filaments have been studied for several decades, but the detailed physical process through which one erupting filament triggers another is still under debate. Here we investigate a sympathetic event involving successive eruptions of two filaments on 2015 November 15-16, which presented abundant sympathetic characteristics. The two filaments (F1 and F2) were separated by a narrow region of negative polarity, and F1 firstly erupted, producing a two-ribbon flare. When the outward-spreading ribbon produced by F1 approached stable F2, a weak brightening was observ…
The separation of a filament and sigmoid is observed during an X1.4 flare on July 12, 2012 in solar active region 11520, but the corresponding magnetic field change is not clear. We construct a data-constrained magnetohydrodynamic simulation of the filament-sigmoid system with the flux rope insertion method and magnetic flux eruption code, which produces the magnetic field evolution that may explain the separation of the low-lying filament and high-lying hot channel (sigmoid). The initial state of the magnetic model contains a magnetic flux rope with a hyperbolic flux tube, a null point struct…
We present the formation and eruption of a sigmoidal filament driven by rotating network magnetic fields (RNFs) near the center of the solar disk, which was observed by the one-meter aperture New Vacuum Solar Telescope (NVST) at Fuxian Solar Observatory (FSO) on 2018 July 12. Counterclockwise RNFs twist two small-scale filaments at their northeastern foot-point region, giving a rotation of nearly 200 degree within about 140 minutes. The motion of the RNF has a tendency to accelerate at first and then decelerate obviously, as the average rotation speed increased from 10 to 150 ,and then slowed …
We investigate the formation, activation and eruption of a flux rope from the sigmoid active region NOAA 11719 by analyzing E(UV), X-ray and radio measurements. During the pre-eruption period of ~7 hours, the AIA 94 A images reveal the emergence of a coronal sigmoid through the interaction between two J-shaped bundles of loops which proceeds with multiple episodes of coronal loop brightenings and significant variations in the magnetic flux through the photosphere. These observations imply that repetitive magnetic reconnections likely play a key role in the formation of the sigmoidal flux rope …
In this paper, we study in detail the evolution of a mini-sigmiod originating in a cross-equatorial coronal hole, where the magnetic field is mostly open and seriously distinct from the closed background field above active-region sigmoids. The source region first appeared as a bipole, which subsequently experienced a rapid emergence followed by a long-term decay. Correspondingly, the coronal structure initially appeared as arc-like loops, then gradually sheared and transformed into continuously sigmoidal loops, mainly owing to flux cancellation near the polarity inversion line. The temperature…
Using observations from Solar Dynamics Observatory, we studied an interesting example of a sigmoid formation and eruption from small-scale flux canceling regions of active region (AR) 11942. Analysis of HMI and AIA observations infer that initially the AR is compact and bipolar in nature, evolved to sheared configuration consisting of inverse J-shaped loops hosting a filament channel over a couple of days. By tracking the photospheric magnetic features, shearing and converging motions are observed to play a prime role in the development of S-shaped loops and further flux cancellation leads to …
We studied the developing conditions of sigmoid structure under the influence of magnetic non-potential characteristics of a rotating sunspot in the active region (AR) 12158. Vector magnetic field measurements from Helioseismic Magnetic Imager and coronal EUV observations from Atmospheric Imaging Assembly reveal that the erupting inverse-S sigmoid had roots in the location of the rotating sunspot. Sunspot rotates at a rate of 0-5deg/h with increasing trend in the first half followed by a decrease. Time evolution of many non-potential parameters had a well correspondence with the sunspot rotati…
Solar eruptions occurring at different places within a relatively short time interval are considered to be sympathetic. However, it is difficult to determine whether there exists a cause and effect between them. Here we study a failed and a successful filament eruption following an X1.8-class flare on 2014 December 20, in which slipping-like magnetic reconnections serve as a key causal link among the eruptions. Reconnection signatures and effects are: at both sides of the filament experiencing the failed eruption, serpentine ribbons extend along chromospheric network to move away from the fila…
The nature of various plausible causal links between sympathetic events is still a controversial issue. In this work, we present multi-wavelength observations of sympathetic eruptions, associated flares and coronal mass ejections (CMEs) occurring on 2013 November 17 in two close-by active regions. Two filaments i.e., F1 and F2 are observed in between the active regions. Successive magnetic reconnections, caused by different reasons (flux cancellation, shear and expansion) have been identified during the whole event. The first reconnection occurred during the first eruption via flux cancellatio…
Context. Some of the most dynamic active regions are associated with complex photospheric magnetic configurations such as quadrupolar regions, and especially ones with a $δ$-spot configuration and a strong Polarity Inversion Line (PIL). Aims. We study the formation and eruption of magnetic flux ropes in quadrupolar regions. Methods. 3D MHD simulations of the partial emergence of a highly twisted flux tube from the solar interior into a non-magnetized stratified atmosphere. Results. We emerge two $Ω$-shaped loops forming a quadrupolar region. The emerging flux forms two initially separated bipo…
Solar extreme ultraviolet (EUV) waves are large-scale propagating disturbances in the corona. It is generally believed that the vital key for the formation of EUV waves is the rapid expansion of the loops that overlie erupting cores in solar eruptions, such as coronal mass ejections (CMEs) and solar jets. However, the details of the interaction between the erupting cores and overlying loops are not clear, because that the overlying loops are always instantly opened after the energetic eruptions. Here, we present three typical jet-driven EUV waves without CME to study the interaction between th…
In this article, we investigate the formation and disruption of a coronal sigmoid from the active region (AR) NOAA 11909 on 07 December 2013, by analyzing multi-wavelength and multi-instrument observations. Our analysis suggests that the formation of `transient' sigmoid initiated $\approx$1 hour before its eruption through a coupling between two twisted coronal loop systems. A comparison between coronal and photospheric images suggests that the coronal sigmoid was formed over a simple $β$-type AR which also possessed dispersed magnetic field structure in the photosphere. The line-of-sight phot…
Using the observations from the Optical and Near-infrared Solar Eruption Tracer and the Solar Dynamics Observatory, we study an M5.7 flare in AR 11476 on 2012 May 10 and a micro-flare in the quiet Sun on 2017 March 23. Before the onset of each flare, there is a reverse S-shaped filament above the polarity inversion line. Then the filaments become unstable and begin to rise. The rising filaments gain the upper hand over the tension force of the dome-like overlying loops and thus successfully erupt outward. The footpoints of the reconnecting overlying loops successively brighten and are observed…
Using multi-wavelength observation from SDO and STEREO, we investigated the mechanism of two successive eruptions (F1 & F2) of a filament in active region NOAA 11444 on 27 march, 2012. The filament was inverse `J' shaped and lying along a quasi-circular polarity inversion line (PIL). The first part of the filament (F1) erupted at ~2:30UT on 27 March 2012, the second part of the filament (F2) erupted at around 4:20 UT on the same day. A precursor/pre-flare brightening was observed below filament's main axis about 30 min prior to F1. The brightening was followed by a jet-like ejection below fila…
Compound eruptions represent that multiple closely spaced magnetic structures erupt consecutively within a short interval, and then lead to a single flare and a single CME. However, it is still subtle for the links between multiple eruptions and the associated single flare or/and single CME. In this Letter, we report the compound eruptions of twin close flux ropes (FR1 and FR2) within a few minutes that resulted in a flare with a single soft X-ray peak and a CME with two cores. The successive groups of expanding loops and double peaks of intensity flux in AIA cool wavelengths indicate two epis…
Extreme ultraviolet (EUV) waves are impressive coronal propagating disturbances. They are closely associated with various eruptions, and can used for the global coronal seismology and the acceleration of solar energetic particles. Hence, the study of EUV waves plays an important role in solar eruptions and Space Weather. Here we present an EUV wave associated with a filament activation that did not evolve into any eruption. Due to the continuous magnetic flux emergence and cancellation around its one end, the filament rose with untwisting motion, and the filament mass flowed towards another en…
Using the high-quality observations of the Solar Dynamics Observatory, we present the interaction of two filaments (F1 and F2) in a long filament channel associated with twin coronal mass ejections (CMEs) on 2016 January 26. Before the eruption, a sequence of rapid cancellation and emergence of the magnetic flux has been observed, which likely triggered the ascending of the west filament (F1). The east footpoints of rising F1 moved toward the east far end of the filament channel, accompanying with post-eruption loops and flare ribbons. It likely indicated a large-scale eruption involving the l…
Filament eruptions occurring at different places within a relatively short time internal, but with a certain physical causal connection are usually known as sympathetic eruption. Studies on sympathetic eruptions are not uncommon. However, in the existed reports, the causal links between sympathetic eruptions remain rather speculative. In this work, we present detailed observations of a sympathetic filament eruption event, where an identifiable causal link between two eruptive filaments is observed. On 2015 November 15, two filaments (F1 in the north and F2 in the south) were located at the sou…
In this paper, we present a multi-wavelength analysis of two X-class solar eruptive flares of classes X2.2 and X9.3 that occurred in the sigmoidal active region NOAA 12673 on 2017 September 6, by combining observations of Atmospheric Imaging Assembly and Helioseismic Magnetic Imager instruments on board the Solar Dynamics Observatory. On the day of the reported activity, the photospheric structure of the active region displayed a very complex network of $δ$-sunspots that gave rise to the formation of a coronal sigmoid observed in the hot EUV channels. Both X-class flares initiated from the cor…
Employing Solar Dynamic Observatory/Atmosphertic Imaging Assembly (AIA) multi-wavelength images, we study an eruption of two crossing filaments, and firstly report the current sheets (CSs) connecting the lower flare ribbons and the upper erupting filaments. On July 8, 2014, two crossing filaments are observed in the NOAA active region (AR) 12113. The lower-lying filament rises first, and then meets the higher-lying one. Thereafter, both of them erupt together. The filament eruption draws the overlying magnetic field lines upward, leading to the approach of two legs, with opposite magnetic pola…
We present results from a set of numerical simulations aimed at exploring the mechanism of coronal mass ejection (CME) suppression in active stars by an overlying large-scale magnetic field. We use a state-of-the-art 3D magnetohydrodynamic (MHD) code which considers a self-consistent coupling between an Alfvén wave-driven stellar wind solution, and a first-principles CME model based on the eruption of a flux-rope anchored to a mixed polarity region. By replicating the driving conditions used in simulations of strong solar CMEs, we show that a large-scale dipolar magnetic field of $75$ G is abl…
Solar eruptive events such as coronal mass ejections and eruptive flares are frequently associated with the emergence of magnetic flux from the convection zone into the corona. We use three dimensional magnetohydrodynamic numerical simulations to study the interaction of coronal magnetic fields with emerging flux and determine the conditions that lead to eruptive activity. A simple parameter study is performed, varying the relative angle between emerging magnetic flux and a pre-existing coronal dipole field. We find that in all cases, the emergence results in a sheared magnetic arcade that tra…
We present a multi-wavelength investigation of a C-class flaring activity that occurred in the active region NOAA 12734 on 8 March 2019. The investigation utilises data from AIA and HMI on board the SDO and the Udaipur-CALLISTO solar radio spectrograph of the Physical Research Laboratory. This low intensity C1.3 event is characterised by typical features of a long duration event (LDE), viz. extended flare arcade, large-scale two-ribbon structures and twin coronal dimmings. The eruptive event occurred in a coronal sigmoid and displayed two distinct stages of energy release, manifested in terms …
We apply the magneto-frictional approach to investigate which quantity or quantities can best predict the loss of equilibrium of a translationally-invariant magnetic flux rope. The flux rope is produced self-consistently by flux cancellation combined with gradual footpoint shearing of a coronal arcade which is open at the outer boundary. This models the magnetic field in decaying active regions on the Sun. Such a model permits two types of eruption: episodic small events caused by shearing and relaxation of the overlying arcade, and major eruptions of the main low-lying coronal flux rope. Thro…
Triple coronal hard X-ray source observed by STIX during a failed filament eruption
Space Research Centre, Polish Academy of Sciences（波兰科学院空间研究中心）；Astronomical Institute, University of Wrocław（弗罗茨瓦夫大学天文研究所）；ETH-Zürich（苏黎世联邦理工学院）；PMOD/WRC（帕默尔太阳物理观测站/世界辐射中心）
We present observations of the eruption and then reformation of a filament caused by its nearby emerging magnetic flux. Driven by the emerging magnetic flux, the emerged positive fluxes moved toward and cancelled with its nearby negative fluxes, where the negative ends of a filament channel beneath the filament and a bundle of left-skewed coronal loops overlying the filament were anchored. Complemented by the nonlinear force-free field extrapolation, we find that the coronal magnetic field lines associated with the filament channel and the emerging magnetic fields consist of sheared field line…
Heating of quiescent coronal loops caused by nearby eruptions observed with the Solar Dynamics Observatory and the Solar Upper Transition Region Imager
We investigate two sympathetic filament eruptions observed by the New Vacuum Solar Telescope (NVST) on 2015 October 15. The full picture of the eruptions is obtained from the corresponding SDO/AIA observations. The two filaments start from active region NOAA 12434 in the north and end in one large quiescent filament channel in the south. The left filament erupts firstly, followed by the right filament eruption about 10 minutes later. Clear twist structure and rotating motion are observed in both filaments during the eruption. Both eruptions are failed, since the filaments firstly rise up, then…
We present evidence that a magnetic flux rope was formed before a coronal mass ejection (CME) and its associated long-duration flare during a pair of preceding confined eruptions and associated impulsive flares in a compound event in NOAA Active Region 12371. Extreme-ultraviolet images and the extrapolated nonlinear force-free field show that the first two, impulsive flares, SOL2015-06-21T01:42, result from the confined eruption of highly sheared low-lying flux, presumably a seed flux rope. The eruption spawns a vertical current sheet, where magnetic reconnection creates flare ribbons and loop…
Sigmoid-to-Flux-Rope Transition Leading to A Loop-Like Coronal Mass Ejection
S型面是太阳爆发最重要的前兆结构之一。在这封信中，我们研究了2010年8月1日的S型喷发，使用太阳动力学观测站（SDO）上的大气成像组件（AIA）获得的EUV数据。在AIA 94（Fe XVIII; 6 MK）中，首次明确观察到由于系链切割重连引起的拓扑重构，即，两个相对的J形环重新连接形成一个连续的S形环，其中心部分沿着磁极性反转线（PIL）倾斜并对齐，以及一个穿过PIL的紧凑环。光球流和日冕系绳切割重连之间的因果关系证明了持续收敛流朝向PIL使用视线磁图获得的日震和磁成像仪（HMI）上SDO的检测。S形环在低日冕中保持准平衡状态约50分钟，中央下沉部分以约10 km s-1的速度缓慢上升。然后在GOES级C3.2耀斑爆发前10分钟，速度增加到约60 km s-1，因为S形环加速了其向拱形环的转变，最终导致环状日冕物质抛射（CME）。AIA的观察结合H？滤波图以及硬X射线（HXR）成像和光谱学与大多数耀斑环是一致的，所述耀斑环是通过将包裹上升通量绳的较少剪切的J形环的拉伸腿重新连接而形成的，与标准的系绳切割方案一致。
Large-scale contraction and subsequent disruption of coronal loops during various phases of the M6.2 flare associated with the confined flux rope eruption
This Letter reports observations of an event that connects all major classes of solar eruptions: those that erupt fully into the heliosphere versus those that fail and are confined to the Sun, and those that eject new flux into the heliosphere, in the form of a flux rope, versus those that eject only new plasma in the form of a jet. The event originated in a filament channel overlying a circular polarity inversion line (PIL) and occurred on 2013-03-20 during the extended decay phase of the active region designated NOAA 12488/12501. The event was especially well-observed by multiple spacecraft …
Using HINODE/XRT, GOES, SDO/AIA observations, we study a compact C-1.4 class flare outside a major sunspot of AR 12178 on 4 October 2014. This flare is associated with a peculiar coronal jet, which is erupted in two stages in the overlying corona above the compact flaring region. At the time of flare maximum, the first stage of the jet eruption occurs above the flare energy release site, and thereafter in the second stage its magneto-plasma system interacts with the overlying distinct magnetic field domain in its vicinity to build further the typical jet plasma column.
We investigate the eruption of a quiescent filament located close to an active region. Large-scale activation was observed in only half of the filament in the form of pre-eruption oscillations. Consequently only this half erupted nearly 30 hr after the oscillations commenced. Time-slice diagrams of 171 Å images from Atmospheric Imaging Assembly were used to study the oscillations. The oscillations were observed in several thin and long features connecting the filament spine to the chromosphere below. This study traces the origin of such features and proposes their possible interpretation. Smal…
