We study the vector magnetic field of a filament observed over a compact Active Region Neutral Line. Spectropolarimetric data acquired with TIP-II (VTT, Tenerife, Spain) of the 10830 Åspectral region provide full Stokes vectors which were analyzed using three different methods: magnetograph analysis, Milne-Eddington inversions and PCA-based atomic polarization inversions. The inferred magnetic field strengths in the filament are of the order of 600 - 700 G by all these three methods. Longitudinal fields are found in the range of 100 - 200 G whereas the transverse components become dominant, with fields as large as 500 - 600 G. We find strong transverse fields near the Neutral Line also at photospheric levels. Our analysis indicates that strong (higher than 500 G, but below kG) transverse magnetic fields are present in Active Region filaments. This corresponds to the highest field strengths reliably measured in these structures. The profiles of the Helium 10830 Ålines observed in this Active Region filament are dominated by the Zeeman effect.
We present the observations of three sympathetic filament eruptions occurring on 19 July 2015 namely F1, F2, and F3. The events were observed in UV/EUV wavelengths by Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory and by Global Oscillation Network Group telescope in Hα line. As filament F1 starts to erupt, a part of it falls close to the location of the F2 and F3 filaments. This causes the eruption of F2 and F3 during which the two filaments merge together and trigger a medium-class CME and a long-duration GOES C2.1 class flare. We discuss the dynamics and kinematics of th…
With the observations of SDO/AIA 304 Å and NVST Hα bands, we present the formation process of an active-region filament in active region NOAA 11903 during the period from 02:00 UT to 10:00 UT on November 25, 2013. A series of jets occurring in the vicinity of the south-western footpoint of the filament directly ejected cool and hot plasma to filament height and supplied material for the filament. Some newly emerging flux is found in the vicinity of the filament south-western footpoint during these jets. In this paper, we mainly focus on the material supply of the filament. The plasma mass uplo…
To better understand magnetic structure and eruptive process of solar filaments, a solar active-region filament (labeled F2) eruption associated with a B-class flare was investigated by using high-resolution H$α$ data from the 1 m New Vacuum Solar Telescope (NVST), combined with EUV observations of the Solar Dynamical Observatory (SDO). The filament F2 was disturbed by another filament (labeled F1) eruption that experienced a whip-like motion. Before the filament F2 eruption, the Dopplergrams show that the southern and the northern parts of the filament F2 body exhibit blueshift and redshift a…
The Non-Eruptive Reconfiguration of a Quiescent Filament After a Nearby Active Region Emergence
University College London（伦敦大学学院）；Mullard Space Science Laboratory（马拉德空间科学实验室）；University of Vienna（维也纳大学）；Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center（达沃斯物理气象观测台/世界辐射中心）；ETH Zürich（苏黎世联邦理工学院）；Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系统研究所）；Northumbria University（诺森比亚大学）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）
We analyze the high-resolution observations from the 1.6m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing as observed in Halpha off-bands. The apparent speed of the flow is around 10 to 60 km/s in the filament, decreasing to 5 to 20 km/s in the light bridge. The most intriguing results…
The determination of the magnetic filed vector in solar filaments is possible by interpreting the Hanle and Zeeman effects in suitable chromospheric spectral lines like those of the He I multiplet at 10830 A. We study the vector magnetic field of an active region filament (NOAA 12087). Spectropolarimetric data of this active region was acquired with the GRIS instrument at the GREGOR telescope and studied simultaneously in the chromosphere with the He I 10830 A multiplet and in the photosphere with the Si I 10827 A line. As it is usual from previous studies, only a single component model is use…
A large-scale, horse-shoe-like filament was investigated and the magnetic field around it was reconstructed. This is an intermediate filament (IF) that appeared on the solar disk for the first time at 02:00 UT on 2015 November 7, and took 8 days to move to the central median on the solar disk. The active region AR 12452 around which the filament occurred was diffuse so that the magnetic field nearby was weak, the average field strength is 106 G. Therefore, the existing approaches to extrapolating the coronal magnetic field and to constructing the filament configuration in the region with stron…
We present a formation process of a filament in active region NOAA 12574 during the period from 2016 August 11 to 12. Combining the observations of GONG H$α$, Hida spectrum and SDO/AIA 304 A, the formation process of the filament is studied. It is found that cool material ($T\sim10^4$ K) is ejected by a series of jets originating from the western foot-point of the filament. Simultaneously, the magnetic flux emerged from the photosphere in the vicinity of the western foot-point of the filament. These observations suggest that cool material in the low atmosphere can be directly injected into the…
Magnetic structure of an activated filament in a flaring active region
虽然人们对静态磁致伸缩中的磁场进行了广泛的研究，但对激活磁致伸缩中的磁场却知之甚少。本文介绍了耀斑活动区激活暗条的磁场结构的观测结果。我们研究，特别是，它的磁结构和视线流在其早期激活阶段，不久之前，它显示出旋转的迹象。我们反演了在特内里费岛VTT观测到的色球He I 10830 A三线态和光球Si I 10827 A线的Stokes轮廓。利用这些反演结果，我们提出和解释的速度和磁场的第一张地图中获得的激活灯丝，在光球和色球。在暗条的色球层中发现了多达5种不同的磁性成分，而在暗条之外，一个单一的成分就足以重现观测结果。显示向上流动的磁性部件优选地朝向细丝的中心定位，而向下流动沿着细丝的外围集中。此外，向上流动的气体与相对于光球的极性相反的磁性配置相关联，而向下流动的气体与相同极性的配置相关联。激活的灯丝具有相当复杂的结构。尽管如此，在正常配置中，它与磁通绳兼容，尽管是扭曲的磁通绳。观测结果最好用上升的通量绳来解释，其中一部分细丝材料仍然稳定地储存（向上流动的材料，随着场上升），而另一部分不再稳定地储存并沿着场线向下流动。
Our aim is to demonstrate the limitations of using a single component model to study the magnetic field of an active region filament. For that we have analyzed the polarimetric signals of the He I 10830 A multiplet acquired with the infrared spectrograph GRIS of the GREGOR telescope (Tenerife, Spain). After a first analysis of the general properties of the filament using Hazel under the assumption of a single component model atmosphere, in this second part we focus our attention on the observed Stokes profiles and the signatures which cannot be explained with this model. We have found an optic…
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…
Recent observations of the solar photosphere revealed the presence of elongated filamentary bright structures inside sunspot umbrae, called umbral filaments (UFs). These features differ in morphology, magnetic configuration, and evolution from light bridges that are usually observed to intrude in sunspots. To characterize an UF observed in the umbra of the giant leading sunspot of active region NOAA 12529, we analyze high-resolution observations taken in the photosphere with the spectropolarimeter aboard the Hinode satellite and in the upper chromosphere and transition region with the IRIS tel…
Quiescent filaments appear as absorption features on the solar disk when observed in chromospheric lines and at continuum wavelengths in the millimeter (mm) range. Active region (AR) filaments are their small-scale, low-altitude analogues, but they could not be resolved in previous mm observations. This spectral diagnostic can provide insight into the details of the formation and physical properties of their fine threads, which are still not fully understood. Here, we shed light on the thermal structure of an AR filament using high-resolution brightness temperature ($T_{\rm b}$) maps taken wit…
An active region filament studied simultaneously in the chromosphere and photosphere: I - Magnetic structure
本文对紧凑型活动区（AR）灯丝（NOAA 10781）中的矢量磁场进行了多波长、多高度的研究。我们提出了一个进化的情况下，这种灯丝。用TIP-II在包括色球He I 10830 A多重峰和光球Si I 10827 A谱线的光谱范围内获得全斯托克斯矢量。在2005年7月3日的He I吸收图像中检测到AR细丝（在我们的观测运行之前形成）。色球矢量磁场在这部分的灯丝强烈剪切，而光球场线下面有一个相反的极性配置。从7月3日到7月5日，记录了极性反转线（PIL）两侧极性的打开和关闭，类似于最近发现的Hinode看到的滑动门效应过程。7月5日，从色球层光谱中推断出一个正常的极性结构，同时在光球层中发现了与PIL对齐的强烈剪切场线。在同一数据集中，在FOV的不同部分也观察到了细丝的脊柱，并通过硅线芯清楚地映射。所推断的灯丝的矢量磁场建议磁通绳拓扑结构。此外，观测表明暗条被分成两部分，一部分位于色球层，另一部分被困在光球层。因此，只有螺旋结构的顶部才能被氦线看到。在PIL的孔隙和孤儿半影似乎是光球对应的极低的灯丝。我们认为，孤立半影形成于致密AR的非常狭窄的PIL中，是光球中通量绳的光球表现。
Magnetohydrodynamics simulation of active region NOAA 11515 is performed to examine the initiation of the M5.6 flaring event that starts around 10:43 UT on 2012 July 2. The simulation is conducted using an extrapolated non-force-free magnetic field generated from the photospheric vector magnetogram of the active region as the initial magnetic field. The magnetic field shows the presence of a three-dimensional (3D) magnetic null with the corresponding dome overlying a filament and a low-lying magnetic flux rope, observed in 304~Å~ and 131~Å~ respectively. The simulated dynamics, triggered by th…
We present an investigation of partial filament eruption on 2012 June 17 in the active region NOAA 11504. For the first time, we observed the vertical splitting process during the partial eruption with high resolution narrow band images at 10830 . The active filament was rooted in a small sunspot of the active region. Particularly, it underwent the partial eruption in three steps, i.e. the precursor, the first eruption, and the second eruption, while the later two were associated with a C1.0 flare and a C3.9 flare, respectively. During the precursor, slow magnetic reconnection took place betwe…
An active region filament in the upper chromosphere is studied using spectropolarimetric data in He I 10830 A from the GREGOR telescope. A Milne-Eddingon based inversion of the Unno-Rachkovsky equations is used to retrieve the velocity and the magnetic field vector of the region. The plasma velocity reaches supersonic values closer to the feet of the filament barbs and coexist with a slow velocity component. Such supersonic velocities result from the acceleration of the plasma as it drains from the filament spine through the barbs. The line-of-sight magnetic fields have strengths below 200 G i…
We study the recurring jets near AR11176 during the period 2011 March 31 17:00 UT to April 1 05:00 UT using observations from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). Mini-filaments (mini-filament1 & 2) are found at the base of these recurring jets where mini-filament1 shows the partial signature of eruption in case of Jet1-3. However, the mini-filament2 shows a complete eruption driving a full blow-out jet (Jet4). The eruption of mini-filament2 triggers C-class flare and Jet4 eruption. The eruption of Jet4 triggers a coronal mass ejection (CME). The pl…
The full 3-D vector magnetic field of a solar filament prior to eruption is presented. The filament was observed with the Facility Infrared Spectropolarimeter at the Dunn Solar Telescope in the chromospheric He i line at 10830 Å on May 29 and 30, 2017. We inverted the spectropolarimetric observations with the HAnle and ZEeman Light (HAZEL) code to obtain the chromospheric magnetic field. A bimodal distribution of field strength was found in or near the filament. The average field strength was 24 Gauss, but prior to the eruption we find the 90th percentile of field strength was 435 Gauss for th…
Sun-as-a-star analyses, in which observational data is spatially integrated, are useful for interpreting stellar data. For future applications to stellar observations, we performed Sun-as-a-star analyses of H$α$ spectra for various active events on the Sun, not only for flares and filament eruptions/surges on the solar disk, but also for eruptions of off limb prominences using H$α$ spectral images taken by the Solar Magnetic Activity Research Telescope / Solar Dynamics Doppler Imager (SMART/SDDI) at Hida Observatory, Kyoto University. All the analyzed events show emission relative to the pre-e…
It is often envisaged that dense filament material lies in the dips of magnetic field lines belonging to either a sheared arcade or a magnetic flux rope. But it is also debated which configuration correctly depicts filaments' magnetic structure, due to our incapacity to measure the coronal magnetic field. In this paper, we address this issue by employing mass motions in an active-region filament to diagnose its magnetic structure. The disturbance in the filament was driven by a surge initiated at the filament's eastern end in the NOAA active region 12685, which was observed by the 1-m New Vacu…
We observed an H$α$ surge occurred in the active region NOAA 12401 on 2015 August 17, and discuss its trigger mechanism, kinematic and thermal properties. It is suggested that this surge is caused by a chromospheric reconnection which ejects cool and dense material with the transverse velocity about 21-28 km s$^{-1}$ and the initial doppler velocity of 12 km s$^{-1}$. This surge is similar to the injection of newly formed filament materials from their footpoints, except that the surge here occurred in a relatively weak magnetic environment of ~100 G. Thus we discuss the possibility of filament…
Hand-drawn synoptic maps from the Meudon Observatory (1919 onwards) and the McIntosh archive (1967 onwards) are two important sources of long-term, manually recorded filament observations. In this study, we calibrate the Meudon maps and subsequently identify filaments through an automated method. We extract physical parameters from this filament database and perform a comparative study of their long-term evolution focusing on the cotemporal period of McIntosh and Meudon observations. The spatio-temporal evolution of filaments manifests in the form of a filament butterfly diagram, indicating fu…
We have carried out a statistical study of the average orientation of the magnetic field in solar filaments with respect to their axes for more than 400 samples, based on data taken with daily full-Sun, full-Stokes spectropolarimetric observations using the He I 1083.0 nm line. The major part of the samples are the filaments in the quiet areas, but those in the active areas are included as well. The average orientation of the magnetic field in filaments shows a systematic property depending on the hemisphere; the direction of the magnetic field in filaments in the northern (southern) hemispher…
Vector Magnetic Field associated with an Active Region Filament Observed by SUNRISE III/SCIP in the Ca II 8542 Å Line
Nagoya University（名古屋大学）；Institute for Space-Earth Environmental Research, Nagoya University（名古屋大学地球·宇宙环境研究所）；National Astronomical Observatory of Japan（日本国立天文台）；The Graduate University for Advanced Studies（高级研究院）；Kanazawa University（金泽大学）；Max Planck Institute for Solar System Research（马普太阳系研究所）；National Institute for Fusion Science（国立研究开发法人核融合科学研究所）
利用SUNRISE III/SCIP在Ca II 8542 Å谱线的高空间分辨率偏振观测，首次明确探测到暗条区域的线性极化信号，通过弱场近似得到约-80 G的视线磁场和300-500 G的横向磁场，为研究低层色球暗条矢量磁场结构提供了新窗口。
We use the POLARIS radiative transport code to generate predictions of the two main observables directly sensitive to the magnetic field morphology and strength in filaments: dust polarization and gas Zeeman line splitting. We simulate generic gas filaments with power-law density profiles assuming two density-field strength dependencies, six different filament inclinations, and nine distinct magnetic field morphologies, including helical, toroidal, and warped magnetic field geometries. We present idealized spatially resolved dust polarization and Zeeman-derived field strengths and directions m…
