We investigate the temporal evolution of magnetic flux emerging within a granule in the quiet-Sun internetwork at disk center. We combined IR spectropolarimetry performed in two Fe I lines at 1565 nm with speckle-reconstructed G-band imaging. We determined the magnetic field parameters by a LTE inversion of the full Stokes vector using the SIR code, and followed their evolution in time. To interpret the observations, we created a geometrical model of a rising loop in 3D. The relevant parameters of the loop were matched to the observations where possible. We then synthesized spectra from the 3D model for a comparison to the observations. We found signatures of magnetic flux emergence within a growing granule. In the early phases, a horizontal magnetic field with a distinct linear polarization signal dominated the emerging flux. Later on, two patches of opposite circular polarization signal appeared symmetrically on either side of the linear polarization patch, indicating a small loop-like structure. The mean magnetic flux density of this loop was roughly 450 G, with a total magnetic flux of around 3x10^17 Mx. During the ~12 min episode of loop occurrence, the spatial extent of the loop increased from about 1 to 2 arcsec. The middle part of the appearing feature was blueshifted during its occurrence, supporting the scenario of an emerging loop. The temporal evolution of the observed spectra is reproduced to first order by the spectra derived from the geometrical model. The observed event can be explained as a case of flux emergence in the shape of a small-scale loop.
Small bipolar magnetic features are observed to appear in the interior of individual granules in the quiet Sun, signaling the emergence of tiny magnetic loops from the solar interior. We study the origin of those features as part of the magnetoconvection process in the top layers of the convection zone. Two quiet-Sun magnetoconvection models, calculated with the radiation-magnetohydrodynamic (MHD) Bifrost code and with domain stretching from the top layers of the convection zone to the corona, are analyzed. Using 3D visualization as well as a posteriori spectral synthesis of Stokes parameters,…
We study the photospheric evolution of an exploding granule observed in the quiet Sun at high spatial ($0.3^{\prime\prime}$) and temporal (31.5 s) resolution by the imaging magnetograph Sunrise/IMaX in June 2009. These observations show that the exploding granule is cospatial to a magnetic flux emergence event occurring at mesogranular scale (up to 12 Mm$^{2}$ area). Using a modified version of the SIR code for inverting the IMaX spectropolarimetric measurements, we obtain information about the magnetic configuration of this photospheric feature. In particular, we find evidence of highly incli…
Recent observations demonstrated that emerging flux regions, which constitute the early stage of solar active regions, consist of emergence of numerous small-scale magnetic elements. They in turn interact, merge, and form mature sunspots. However, observations of fine magnetic structures on photosphere with sub-arcsecond resolution are very rare due to limitations of observing facilities. In this work, taking advantage of the high resolution of the 1.6 m Goode Solar Telescope, we jointly analyze vector magnetic fields, continuum images, and Hα observations of NOAA AR 12665 on 2017 July 13, wit…
Aims. Moreno-Insertis et al. (2018) recently discovered two types of flux emergence in their numerical simulations: magnetic loops and magnetic sheet emergence. Whereas magnetic loop emergence has been documented well in the last years, by utilising high-resolution full Stokes data from ground-based telescopes as well as satellites, magnetic sheet emergence is still an understudied process. We report here on the first clear observational evidence of a magnetic sheet emergence and characterise its development. Methods. Full Stokes spectra from the Hinode spectropolarimeter were inverted with th…
Granular-Scale Elementary Flux Emergence Episodes in a Solar Active Region
我们分析了在AR 11024出现期间两个54分钟内拍摄的Hinode航天器的数据。我们专注于小规模的部分内观察到的太阳活动区，并发现非常独特的小规模和短暂的黑暗功能的Ca II H色球过滤图和斯托克斯我的图像的外观。这些特征出现在纵向磁场接近于零的区域，并且在它们最终消失之前观察到长度增加。当暗特征逐渐消失时，在低色球层谱线中检测到能量释放。在时间序列的磁图中，观测到一个发散的双极结构，伴随着暗特征和亮特征的出现。观测到的现象被解释为证明在太阳大气中的元素通量出现，即小规模的拱丝系统上升到较低的色球层与几个太阳颗粒的长度尺度。增亮被解释为色球加热的签名所引发的重新连接的上升环路（一旦他们达到色球高度）与预先存在的磁场，以及重新连接/取消事件中的U-环段出现的蛇形字段。我们研究的时间演化和动态的事件，并将它们与出现在安静的太阳区域和蛇形磁通出现签名检测到的活动区域的磁回路。阐述了本研究中提出的颗粒尺度通量出现的新特征，我们提出了蛇纹石通量出现的方案。
Emergence of small-scale magnetic loops through the quiet solar atmosphere
我们在极小的空间尺度上研究了宁静太阳中磁通量的出现，着重于光球层和色球层之间的磁联系。观测数据包括分光偏振测量和用Hinode卫星和荷兰开放望远镜拍摄的滤光图。我们发现，一个显着的比例存在于互联网络区域的磁通量出现在Ω形回路的形式。出现率为每小时0.02圈/角秒^{-2}，这将为太阳表面带来1.1 x 10^12 Mx s^{-1}角秒^{-2}的新通量。最初，观察到的环是颗粒细胞上方的小块线性极化。不久之后，两个相反极性的足迹在颗粒内部或边缘的圆偏振中变得可见，并开始向相邻的粒间空间移动。足点的方向似乎不遵守黑尔的极性规则。环不断地受到对流运动的冲击，但它们总是保持高度的连贯性。有趣的是，光球层中出现的环有23%到达色球层（69个中有16个）。它们首先在Fe I 630 nm磁图中被检测到，5分钟后在Mg I b 517.3 nm磁图中被检测到。大约8分钟后，其中一些也在Ca II H线核心图像中观察到，其中足点产生小的亮度增强。
Loops are one of the fundamental structures that trace the geometry of the magnetic field in the solar atmosphere. Their evolution and dynamics provide a crucial proxy for studying how the magnetized structures are formed and heated in the solar atmosphere. Here, we report on spectroscopic observations of a set of transition region loops taken by the Interface Region Imaging Spectrograph (IRIS) at Si IV 1394 Å with a sit-and-stare mode. The loops are corresponding to the flux emergence at its very late phase when the emerged magentic features in the photosphere have fully developed. We find th…
Emergence of granular-sized magnetic bubbles through the solar atmosphere: I. Spectropolarimetric observations and simulations
我们研究了2009年7月发生在NOAA 11024中的颗粒大小的磁通量出现事件。这些观测是用瑞典1米太阳望远镜上的CRISP分光偏振仪进行的，空间分辨率为0.14”。同时全斯托克斯观测的两个光球Fe I线在630.2 nm和色球Ca II 854.2 nm线，使我们能够详细描述整个太阳大气的出现过程。我们在这里报告的3D半球形气泡事件，而不是简单的磁足点，我们观察到复杂的半圆形脚跨越几个颗粒。在这些事件中最具特征的签名是在Ca II 854.2 nm线的翅膀上拍摄的滤光片中观察到一个黑暗的气泡。我们可以推断气泡是如何通过太阳大气层上升的，因为我们看到它从Ca II 854.2 nm的翅膀发展到核心。在光球层中，磁泡的平均向上多普勒速度为2 km/s。在大约3.5分钟内，它将行进约1100公里到达色球层中部，这意味着平均上升速度为5.2公里/秒。为了帮助解释的意见，我们进行了三维数值模拟的演变的水平，无扭曲的磁通量片注入对流区，使用彩虹代码。计算区域从对流层上部到日冕下部。在模拟的色球层中，上升的通量片产生一个大的、冷的、磁化的气泡。我们将这个气泡与观测到的气泡进行比较，发现非常一致，包括光球层和色球层中类似的场强和速度信号，温度赤字，上升速度，膨胀速度和寿命。
Solar active regions are associated with Evershed outflows in sunspot penumbrae, moat outflows surrounding sunspots, and extended inflows surrounding active regions. The latter have been identified on established active regions by various methods. The evolution of these inflows and their dependence on active region properties as well as their impact on the global magnetic field are not yet understood. We aim to understand the evolution of the average inflows around emerging active regions and to derive an empirical model for these inflows. We analyze horizontal flows at the surface of the Sun …
Magnetic Configurations Related to the Coronal Heating and Solar Wind Generation I. Twist and Expansion Profiles of Magnetic Loops Produced by Flux Emergence
Chromospheric Jet and Growing "Loop" Observed by Hinode: New Evidence of Fan-Spine Magnetic Topology Resulting From Flux Emergence
我们目前的观测色球喷流和不断增长的“环”系统，显示了新的证据，扇脊拓扑结构导致磁通量出现。这一事件发生在2007年2月9日的赤道冕洞，由日野太阳光学望远镜在Ca II H线上以前所未有的细节观测到。喷流的前身是一束延伸到色球层上方的细物质线，似乎以约50 km/s（周期<200 s）的速度围绕束轴旋转。这些旋转或横向振荡以高达786 km/s的速度向上传播。这个星系团先是缓慢地向上摆动，然后迅速地向上摆动，转变发生在A4.9耀斑的开始。一个环在这两个阶段同时膨胀（速度：16-135 km/s）。在耀斑的峰值附近，环似乎破裂;同时向上喷出物和质量下降流比自由落体更快地出现在一个环腿。然后，物质束以鞭打的方式摆动回来，并发展成准直射流，其沿着推断出的开放场线取向，横向振荡以较慢的速率继续。一些物质沿着平滑的流线回落，不再显示振荡。在低海拔，流线分叉，大概在一个磁零点和绕过推断圆顶，描绘了一个倒Y几何形状。这些流线在空间上与晚期Ca II H环和X射线耀斑环密切匹配。这些观察结果与模型一致，即在开放场区域出现的磁通导致磁重联，形成喷流和扇脊拓扑结构。我们提出，物质束和准直射流分别代表准静态和喷发阶段的外脊，而生长环是三维扇面的二维投影。
The heating of coronal loops is investigated to understand the observational consequences in terms of the thermodynamics and radiative losses from the Sun as well as the magnetized coronae of stars with an outer convective envelope. The dynamics of the Parker coronal heating model are studied for different ratios of the photospheric forcing velocity timescale $t_p$ to the Alfvén crossing time along a loop $t_A$. It is shown that for $t_p/t_A \gtrsim$ 10--24 the heating rate and maximum temperature are largest and approximately independent of $t_p/t_A$, leading to a strong emission in X-rays an…
Horizontal flow fields in and around a small active region-- The transition period between flux emergence and decay
目的。将高分辨率观测与天气观测相结合，旨在全面描述光球层通量的出现以及最终形成成熟活动区的增长过程。方法.小活动区NOAA 12118于2014年7月18日被1.5米的格里戈尔太阳望远镜观测到。在GREGOR Fabry-Pérot干涉仪（GFPI）的蓝色成像通道（BIC）中获取的高分辨率蓝色连续谱和G波段图像的时间序列由SDO机载HMI获得的LOS磁图和连续谱图像补充。水平自行和水平等离子体速度分别用局部相关跟踪（LCT）和微分仿射速度估计器计算。采用形态学图像处理方法测量了EFR在其演化过程中的光/磁面积、磁通量和分离轮廓。结果计算的光度区、磁区和磁通量的增长率大约是各自衰减率的两倍。使用HMI五天磁图的时空图描绘了一个叶状结构，这是由两个极性的初始分离，快速扩张阶段，蔓延停滞的时间和区域再次缓慢收缩的时期决定的。0.26 km \s的分离率在初始阶段最高，当分离停止时，分离率减小。水平等离子体速度计算在四个演变阶段表明不断变化的模式的流入。在LCT地图中，我们发现持续的流动模式，如向外运动的两个主要的孔，一个发散的功能附近的拖尾孔标记的网站上涌的等离子体和通量的出现，和低速度在内部的孔。我们在两个主要极性之间检测到许多细长的快速膨胀颗粒。
Densely packed coronal loops are rooted in plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plages are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in plages using high resolution observations and simulations. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the SST. These data were inverted to retrieve th…
We investigate the chromospheric counterpart of small-scale coronal loops constituting a coronal bright point (CBP) and its response to a photospheric magnetic-flux increase accompanied by co-temporal CBP heating. We used co-observations from the AIA and HMI/SDO, together with data from the Fast Imaging Solar Spectrograph taken in the Halpha and Ca II 8542 lines. We used a new multi-layer spectral inversion technique to derive the temporal variations of the temperature of the Halpha loops (HLs). We find that the counterpart of the CBP, as seen at chromospheric temperatures, is composed of a bu…
New Statistical Topology Theory Predicts Turbulent Magnetic Emergence from the Sun's Interior
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Beijing University of Technology（北京工业大学）
Flux ropes are generally believed to be core structures of solar eruptions that are significant for the space weather, but their formation mechanism remains intensely debated. We report on the formation of a tiny flux rope beneath clusters of active region loops on 2018 August 24. Combining the high-quality multiwavelength observations from multiple instruments, we studied the event in detail in the photosphere, chromosphere, and corona. In the source region, the continual emergence of two positive polarities (P1 and P2) that appeared as two pores (A and B)is unambiguous. Interestingly, P2 and…
The polarity of the toroidal magnetic field in the solar convection zone periodically reverses in the course of the 11/22-year solar cycle. Among the various processes that contribute to the removal of `old-polarity' toroidal magnetic flux is the emergence of flux loops forming bipolar regions at the solar surface. We quantify the loss of subsurface net toroidal flux by this process. To this end, we determine the contribution of an individual emerging bipolar loop and show that it is unaffected by surface flux transport after emergence. Together with the linearity of the diffusion process this…
I report on observations of a set of magnetic loops above a region with late-phase flux emergence taken by IRIS, Hinode and SDO. The loop system consists of many transition region loop threads with size of 5--12\arcsec\ in length and $\sim0.5$\arcsec in width and coronal loops with similar length and $\sim2$\arcsec width. Although the loop system consists of threads with different temperatures, most individual loop thread have temperature in a narrow range. In the middle of the loop system, it shows clear systematic blue-shifts of about 10\,\kms\ in the transition region that is consistent wit…
Magnetic reconnection occurs when new flux emerges into the corona and becomes incorporated into the existing coronal field. A new active region (AR) emerging in the vicinity of an existing AR provides a convenient laboratory in which reconnection of this kind can be quantified. We use high time-cadence 171 $Å$ data from SDO/AIA focused on new/old active region pair 11147/11149, to quantify reconnection. We identify new loops as brightenings within a strip of pixels between the regions. This strategy is premised on the assumption that the energy brightening a loop originates in magnetic reconn…
Multi-wavelength high-resolution observations of a small-scale emerging magnetic flux event and the chromospheric and coronal response
最先进的太阳仪器以前所未有的分辨率揭示了太阳的磁活动。大熊太阳天文台的1.6米新太阳望远镜的观测正在我们对太阳表面结构的理解中迈出下一步。颗粒尺度磁通量的出现和太阳大气的响应是其中的关键研究。作为与美国宇航局IRIS任务联合观测计划的一部分，NST在光球和色球波长上观测了活动区NOAA 11810。SDO和Hinode天基望远镜提供了补充数据。该区域显示了一组太阳孔，在其附近，我们检测到一个小规模的浮力水平磁通量管造成异常颗粒化和与预先存在的环境场在高层大气层的相互作用。随着变形颗粒的膨胀，我们观察到HeI数据中突然出现了一个扩展的激增。IRIS捕捉到了与HeI浪涌相关的热等离子体射流的喷射。SDO/HMI数据揭示了新兴的磁环状结构。Hinode/Ca II H和IRIS滤波图详细描述了太阳色球层下部新出现的磁场的连通性。从这些数据中，我们证实，新兴的通量管的方向几乎垂直于上覆的环境场。然而，新出现的磁场线与预先存在的上覆场的相互作用产生高温发射区域并促进浪涌/射流产生。在喘振/射流喷射的第一迹象之前和之后检测局部加热。我们将结果与之前的观察和理论模型进行比较，并提出了激活等离子体射流/浪涌和限制加热的场景。这一过程在日冕物质流和能量流中起着重要的作用。
Coronal jets are always produced by magnetic reconnection between emerging flux and pre-existing overlying magnetic fields. When the overlying field is vertical/obilique or horizontal, the coronal jet will appear as anemone type or two-sided-loop type. Most of observational jets are of the anemone type, and only a few of two-sided-loop jets have been reported. Using the high-quality data from New Vacuum Solar Telescope, Interface Region Imaging Spectrograph, and Solar Dynamics Observatory, we present an example of two-sided-loop jets simultaneously observed in the chromosphere, transition regi…
Plasma flows and magnetic field interplay during the formation of a pore
我们研究了AR NOAA 11462中孔的形成。我们分析了2012年4月17日DST时IBIS获得的数据，包括Fe I 617.3 nm谱线的全斯托克斯测量。此外，我们分析了SDO/HMI观测的连续和矢量磁图来自Fe I 617.3 nm线数据从2012年4月15日至19日。我们估计了磁场强度和矢量分量和LOS和水平运动的光球区托管孔隙形成。我们讨论我们的结果，根据其他观测研究和数值模拟的最新进展。在AR的前导区域中，孔形成在不到1小时内发生。在AR的前部的通量斑块的演变是快的（< 12小时）比在尾部区域的更扩散和更小的尺度通量斑块的演变（20-30小时）。在孔隙形成过程中，磁区与暗区之比从5减小到2。我们在形成的孔隙边界处观察到强烈的下流，并在演变特征附近观察到等离子体的发散自行运动，这些特征指向形成的孔隙。在AR中估计的各种数量的平均值和趋势与以前的稳定孔隙的观测研究的结果一致，并与他们的模拟同行，在最近的数值模拟上升管过程中看到的。与数值研究的结果的协议举行的流量出现过程的签名（如小规模的混合极性模式和细长颗粒的外观）和该地区的演变。通过速度和磁场的综合作用，在不断发展的结构中和周围，驱动孔隙形成的过程被识别为磁通量集中的出现和随后出现的磁通量的重组。
In this study we report detailed observations of magnetic environment at four footpoints of two warm coronal loops observed on 5 May 2016 in NOAA AR 12542 (Loop I) and 17 Dec 2015 in NOAA AR 12470 (Loop II). These loops were connecting a plage region with sunspot periphery (Loop I) and a sunspot umbra (Loop II). We used Solar Dynamics Observatory (SDO) and Goode Solar Telescope (GST) data to describe the phenomenon and understand its causes. The study indicates loop brightening episodes were associated with magnetic flux emergence and cancellation processes observed in SDO's Helioseismic and M…
In this work, we investigate the formation of a magnetic flux rope (MFR) above the central polarity inversion line (PIL) of NOAA Active Region 12673 during its early emergence phase. Through analyzing the photospheric vector magnetic field, extreme ultraviolet (EUV) and ultraviolet (UV) images, extrapolated three-dimensional (3D) non-linear force-free fields (NLFFFs), as well as the photospheric motions, we find that with the successive emergence of different bipoles in the central region, the conjugate polarities separate, resulting in collision between the non-conjugated opposite polarities.…
