Quantifying Properties of Photospheric Magnetic Cancellations in the Quiet Sun Internetwork
Vincent E. Ledvina, Maria D. Kazachenko, Serena Criscuoli, Dennis Tilipman, Ilaria Ermolli, Mariachiara Falco, Salvatore Guglielmino, Shahin Jafarzadeh, Luc Rou… 展开作者
Vincent E. Ledvina, Maria D. Kazachenko, Serena Criscuoli, Dennis Tilipman, Ilaria Ermolli, Mariachiara Falco, Salvatore Guglielmino, Shahin Jafarzadeh, Luc Rouppe van der Voort, Francesca Zuccarello
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19 pages, 18 figures, 2 tables, accepted into ApJ on 06/08/2022
We analyzed spectropolarimetric data from the Swedish 1-meter Solar Telescope to investigate physical properties of small-scale magnetic cancellations in the quiet Sun photosphere. Specifically, we looked at the full Stokes polarization profiles along the Fe I 557.6 nm and of the Fe I 630.1 nm lines measured by CRisp Imaging SpectroPolarimeter (CRISP) to study temporal evolution of the line-of-sight (LOS) magnetic field during 42.5 minutes of quiet Sun evolution. From this magnetogram sequence, we visually identified 38 cancellation events. We then used Yet Another Feature Tracking Algorithm (YAFTA) to characterize physical properties of these magnetic cancellations. We found on average $1.6\times10^{16}$ Mx of magnetic flux cancelled in each event with an average cancellation rate of $3.8\times10^{14}$ Mx s$^{-1}$. The derived cancelled flux is associated with strong downflows, with an average speed of $V_\mathrm{LOS}\approx1.1$ km s$^{-1}$. Our results show that the average lifetime of each event is $9.2$ minutes with an average $44.8\%$ of initial magnetic flux being cancelled. Our estimates of magnetic fluxes provide a lower limit since studied magnetic cancellation events have magnetic field values that are very close to the instrument noise level. We observed no horizontal magnetic fields at the cancellation sites and therefore can not conclude whether the events are associated structures that could cause magnetic reconnection.
It is now well established that the quiet Sun contains in total more magnetic flux than active regions and represents an important reservoir of magnetic energy. But the nature and evolution of these fields remain largely unknown. We investigate the solar-cycle and center-to-limb variations of magnetic-flux structures at small scales in internetwork regions of the quiet Sun. We used Hinode SOT/SP data from the irradiance program between 2008 and 2016. Maps of the magnetic-flux density are derived from the center-of gravity method applied to the FeI 630.15 nm and FeI 630.25 nm lines. To correct …
The importance of the quiet-Sun magnetism is that it is always there to a greater or lesser extent, being a constant provider of energy, independently of the solar cycle phase. The open questions about the quiet-Sun magnetism include those related to its origin. Most people claim that the local dynamo action is the mechanism that causes it. This fact would imply that the quiet-Sun magnetism is nearly the same at any location over the solar surface and at any time. Many works claim that the quiet Sun does not have any variation at all, although a few of them raise doubt on this claim and find m…
Horizontal Magnetic Fields Dominate the Weak Field Quiet Sun in Sunrise III Observations. Evidence from Traditional and Transformer-Based Inversions
Queen’s University Belfast（贝尔法斯特女王大学）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉帕鲁纳大学）；Max-Planck-Institut für Sonnensystemforschung（马克斯·普朗克太阳系统研究所）；Instituto de Astrofísica de Andalucía, CSIC（安达卢西亚天体物理研究所，西班牙高等科学研究委员会）；Spanish Space Solar Physics Consortium（西班牙空间太阳物理学联盟）；National Astronomical Observatory of Japan（日本国立天文台）；The University of Tokyo（东京大学）；The Graduate University for Advanced Studies (SOKENDAI)（高级研究大学院大学）
Pervasive Linear Polarization Signals in the Quiet Sun
本文利用超深偏振光谱数据研究了宁静太阳网络中线偏振信号的分布。我们减少噪音的意见，尽可能多的是可行的，通过增加单缝测量塞曼敏感的Fe I 630 nm线所采取的日出分光偏振仪。积分斯托克斯光谱用于确定由线偏振信号覆盖的视场的分数。我们发现，在盘中心，高达69%的安静太阳表面显示出振幅大于0.032%的斯托克斯Q或U轮廓（是较长积分所达到的7 x 10^{-5}噪声水平的4.5倍）。在大多数安静的太阳中，仅仅存在线性偏振就意味着弱的网络间场必须高度倾斜，但是我们通过将这些像素与斯托克斯Q或U信号反转来量化这一点。这允许场倾斜、场强度和场方位角的精确确定，因为同时使用所有四个斯托克斯光谱所携带的信息。在1.3 x 10^{-4}的噪声水平下，对53%的观测视场进行反演。因此，导出的磁场分布代表了安静的太阳互联网的一半以上。我们的研究结果证实了从以前的分析中得出的结论，主要使用斯托克斯I和V：互联网络领域是非常倾斜的，但除了在方位角，他们似乎不是各向同性分布。
Chromospheric heating due to cancellation of quiet Sun internetwork fields
太阳色球层的加热一直是太阳物理学中最重要的问题之一。我们目前的理解是，小规模互联网（IN）磁场作为一种加热剂发挥了重要作用。事实上，光球层中IN磁性元素的抵消可以在色球层和过渡区产生短暂的增亮。这些明亮的结构可能是能量释放和等离子体加热的标志，可能是由IN场线的磁重联驱动的。虽然单个事件预计不会释放大量的能量，但它们对色球层的全球贡献可能是显着的，因为它们在安静的太阳区域无处不在。在本文中，我们研究取消的IN元素，并分析其对平静的太阳大气的能量学和动力学的影响。我们使用高分辨率，多波长，协调观测获得的接口区域成像光谱仪（IRIS）和瑞典1米太阳望远镜（SST），以确定取消的IN磁通量补丁，并遵循其演变。我们发现，平均而言，这些事件在光球层中的寿命约为3分钟，在色球层和/或过渡区中的寿命约为12分钟。采用多线反演的Mg II H & K线，我们表明，取消产生清晰的签名加热在高层大气层。然而，在SST所能达到的分辨率和灵敏度下，它们的数密度似乎仍然低一个数量级，无法解释全球色球加热。
Structure and Dynamics of Isolated Internetwork Ca II H Bright Points Observed by Sunrise
我们的目标是改善我们的图片在安静的太阳互联网的低色球层通过调查的强度，水平速度，大小和寿命的变化小亮点（BPs;直径小于0.3弧秒）观察到的Ca II H 3968通带沿其磁场参数，来自光球磁图。对从太阳表面空间分辨率约为100公里的“日出”球载太阳望远镜获得的盘心静日观测的若干高质量时间序列进行了分析，以研究在Ca II H通带观测到的BPs动态及其对光球矢量磁图信号的依赖性。参数，如水平速度，直径，强度和寿命直方图的孤立的互联网和磁性钙II H BP。平均值分别为2.2 km/s、0.2 arcsec（150 km）、1.48平均Ca II H宁静太阳和673 sec。有趣的是，BPs的亮度和水平速度是反相关的。大偏移（脉冲）的水平速度，高达15公里/秒，目前在大多数BP的轨迹。这可能激发出进入色球层甚至日冕的扭折波，我们估计扭折波携带的能量通量为310 W/m^2，足以加热上层，尽管只是少量的。稳定的观测条件的日出和我们的技术，用于识别和跟踪BP，使我们能够确定可靠的参数，这些功能在互联网。因此，我们发现，例如，它们的寿命比我们之前认为的要长得多大的速度也是可靠的，并可能激发扭结波。虽然这些波（勉强）能量足以加热安静的日冕，但我们预计来自网络中较大的磁性元素以及部分互联网络的大量额外贡献。
The motion of faint propagating disturbances (PD) in the solar corona reveals an intricate structure which must be defined by the magnetic field. Applied to quiet Sun observations by the Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observatory (SDO), a novel method reveals a cellular network, with cells of typical diameters 50\arcsec\ in the cool 304Å channel, and 100\arcsec\ in the coronal 193Å channel. The 193Å cells can overlie several 304Å cells, although both channels share common source and sink regions. The sources are points, or narrow corridors, of divergence that occupy the cent…
Time series of photospheric magnetic parameters of solar active regions (ARs) are used to answer whether scaling properties of fluctuations embedded in such time series help to distinguish between flare-quiet and flaring ARs. We examine a total of 118 flare-quiet and 118 flaring AR patches (called HARPs), which were observed from 2010 to 2016 by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO). Specifically, the scaling exponent of fluctuations is derived applying the Detrended Fluctuation Analysis (DFA) method to a dataset of 8-day time series of 18 pho…
What Is the Source of Quiet Sun Transition Region Emission?
追溯到对盘上日冕的第一次观测，光球的磁网络和增强的转变温度等离子体发射之间存在着定性的联系。这些观测结果导致了一个通用模型的发展，该模型通过划分具有不同能量平衡的不同磁环几何形状的大气体积来描述发射结构。互联网络是否产生过渡温度辐射？有多少网络通量连接到日冕？安静的太阳辐射与低活动的类太阳恒星相比如何？在这项工作中，我们重新审视了安静太阳的规范模型，并利用IRIS和HMI的高分辨率观测数据来解决这些问题。我们使用超过900深曝光的硅IV 1393 A IRIS随着几乎同时HMI磁图量化之间的相关性过渡温度发射结构和磁场浓度通过一些新的统计。我们的观测结果与分析的Bifrost MHD模型和一个大规模的位场模型。我们的研究结果描绘了一幅安静的太阳的复杂肖像。我们测量的排放签名在遥远的互联网，不能归因于网络的贡献。我们发现，最暗淡的地区的发射是没有联系到当地的垂直磁场。利用MHD模拟，我们将冷的中高空冕环和高空冕环的辐射贡献进行了分类，并讨论了针状体的潜在辐射贡献。我们的结果为耦合太阳大气提供了新的约束，以便我们可以进一步了解动态热结构和磁结构如何在过渡区产生观察到的现象。
Small-scale internetwork (IN) magnetic fields are considered to be the main building blocks of the quiet Sun magnetism. For this reason, it is crucial to understand how they appear on the solar surface. Here, we employ a high-resolution, high-sensitivity, long-duration Hinode/NFI magnetogram sequence to analyze the appearance modes and spatio-temporal evolution of individual IN magnetic elements inside a supergranular cell at the disk center. From identification of flux patches and magnetofrictional simulations, we show that there are two distinct populations of IN flux concentrations: unipola…
Migration of Ca II H bright points in the internetwork
太阳低层大气中类磁亮点特征的迁移反映了磁通量的扩散以及它们所处大气层的水平流动。我们分析固有的磁性，孤立的互联网Ca II H MBPs（平均寿命461 +- 9秒）的自行车的轨迹，以获得他们的扩散行为。我们使用免费的高空间和时间分辨率的图像序列的安静的太阳，光盘中心的意见获得的Ca II H 3968通带的日出滤波成像仪（SuFI）船上的日出球载太阳天文台。自动跟踪互联网络中的小MBP。然后计算每个MBP的轨迹并通过扩散指数（γ）和扩散系数（D）来描述。我们进一步探索的扩散指数的分布与蒙特卡罗模拟的帮助。我们发现，在所有MBP上，平均γ = 1.69 ± 0.08，D = 257 ± 32 km^2/s。大多数MBP的轨迹被分类为超扩散，即，γ > 1，所确定的γ是我们所知的迄今为止所获得的最大值。还获得了D与从所有MBP的轨迹确定的时间尺度（τ）之间的直接相关性。我们讨论了一个简单的场景来解释所观察到的相对短寿命的MBP的扩散率，而它们在超颗粒中的小区域内迁移（即，互联网区域）。我们表明，在个别MBPs得到的γ值的分散是由于其有限的寿命。超扩散的MBPs可以很好地描述为随机步行者（由于颗粒演化和粒间湍流）叠加在一个大的系统（背景）的速度，造成颗粒，中粒和超粒流。
Observational power spectra of the photospheric magnetic field turbulence, of the quiet-sun, were presented in a recent paper by Abramenko and Yurchyshyn. Here I focus on the power spectrum derived from the observations of the Near InfraRed Imaging Spectrapolarimeter (NIRIS) operating at the Goode Solar Telescope. The latter exhibits a transition from a power law with index $-1.2$ to a steeper power law with index $-2.2$, for smaller spatial scales. The present paper presents an interpretation of this change. Furthermore, this interpretation provides an estimate for the effective width of the …
We studied the dynamics of the solar atmosphere in the region of a large quiet-Sun filament, which erupted on 21 October 2010. The filament eruption started at its northern end and disappeared from the H$α$ line-core filtergrams line within a few hours. The very fast motions of the northern leg were recorded in ultraviolet light by AIA. We aim to study a wide range of available datasets describing the dynamics of the solar atmosphere for five days around the filament eruption. This interval covers three days of the filament evolution, one day before the filament growth and one day after the er…
Time series of high resolution photospheric spectra in a quiet region of the Sun. II. Analysis of the variation of physical quantities of granular structures
Internetwork (IN) magnetic fields are highly dynamic, short-lived magnetic structures that populate the interior of supergranular cells. Since they emerge all over the Sun, these small-scale fields bring a substantial amount of flux, and therefore energy, to the solar surface. Because of this, IN fields are crucial for understanding the quiet Sun (QS) magnetism. However, they are weak and produce very small polarization signals, which is the reason why their properties and impact on the energetics and dynamics of the solar atmosphere are poorly known. Here we use coordinated, high-resolution, …
Spatial distribution and statistical properties of small-scale convective vortex-like motions in a quiet Sun region
本文分析了位于拉帕尔马的瑞典1米太阳望远镜对宁静的太阳网间区域的高分辨率观测。我们通过计算时间序列图像上小尺度结构的水平自行来确定太阳光球区小尺度涡旋运动的位置。这些等离子体对流驱动的漩涡运动与以下两个方面有关：（1）下降气流（通常解释为对应于等离子体冷却并因此返回到可见光球层以下的内部的位置），以及（2）水平速度矢量收敛到中心点。下沉核被证明是被动浮子追踪等离子体流向每个漩涡中心的最终目的地。对于这里分析的两个时间序列，我们确定这些事件的发生分别为1.4 x 10^（-3）和1.6 x 10^（-3）涡旋Mm^（-2）min^（-1）。
While the longitudinal field that dominates photospheric network regions has been studied extensively, small scale transverse fields have recently been found to be ubiquitous in the quiet internetwork photosphere. Few observations have captured how this field evolves. We aim to statistically characterise the magnetic properties and observe the temporal evolution of small scale magnetic features. We present two high spatial/temporal resolution observations that reveal the dynamics of two disk centre internetwork regions taken by the new GRIS/IFU (GREGOR Infrared Spectrograph Integral Field Unit…
Photospheric downward plasma motions in the quiet-Sun
我们分析分光偏振数据采取与日之出航天器在安静的太阳区域在磁盘中心。扭曲的红移斯托克斯$V$配置文件被发现显示出的特性的演变，总是遵循相同的相位序列。我们研究了这些事件的统计特性，使用分光偏振数据从Hinode/SP。我们还研究了上层光球和低色球层使用Mg i b2和Ca ii h数据从Hinode。最后，我们应用SIRGAUSS反演码的偏振数据，以推断大气层结的物理参数。我们还得到了这些物理参数考虑到动力学项的运动方程。Stokes V剖面显示了一个以四个不同时间步长演变的凹凸，整个过程持续108秒。斯托克斯I显示出强烈弯曲的红色翼，连续信号在晶间通道内显示出亮点。这个亮点与Mg i b2线的强红移和Ca ii h图像中的明亮特征相关。从斯托克斯轮廓反演得到的模型比平均安静的太阳模型更热，垂直磁场配置和场强在KG值的范围内。它还提出了一个高斯扰动的LOS速度分层，其中心随着时间的推移，移动到更深的层。我们研究了一种特殊类型的事件，它可以被描述为热等离子体的等离子体团，它从光球的顶部向下移动，放置在颗粒间的通道上，并且总是与强磁场浓度有关。我们认为，这种等离子体团的起源可能是一个磁重联，是发生在色球层。
Probing deep photospheric layers of the quiet Sun with high magnetic sensitivity
上下文夫琅和费谱线中极弱的偏振信号阻碍了对安静太阳磁性的研究。光子噪声、杂散光以及塞曼效应对纵向和横向磁场的系统性不同灵敏度导致了在磁场矢量的强度和角分布方面的有争议的结果。目的。分析了接近1.5 m GREGOR望远镜衍射极限的斯托克斯测量的信息含量。我们考虑了空间杂散光和光子噪声的影响。方法.用GREGOR望远镜上的红外偏振分光仪GRIS对太阳盘中心静区进行了高灵敏度的全斯托克斯测量，获得了深光球区1.56 μm Fe I谱线。噪声统计和斯托克斯V不对称性进行了分析，并比较了类似的数据集的日出分光偏振仪（SOT/SP）。直接根据剖面的形状和强度对全球资源信息系统数据进行了简单的诊断。我们利用磁力线比技术，这是测试对MHD模拟。结果在非常平静的太阳区域，大约80%的GRIS光谱显示出3σ以上的偏振信号。面积和振幅的不对称性与小尺度表面发电机MHD模拟结果一致。磁力线比分析揭示了在10到100高斯范围内的普遍存在的磁性区域，具有一些千高斯场的集中。结论.空间分辨率为0.40”的GRIS分光偏振数据在高空间分辨率扫描和高磁场灵敏度的组合方面是迄今为止唯一的。然而，不可避免的影响，空间杂散光和由此产生的稀释弱斯托克斯配置文件意味着反演技术仍然承担着很高的风险误解的数据。
The quiet Sun exhibits a wealth of magnetic activities that are fundamental for our understanding of solar and astrophysical magnetism. The magnetic fields in the quiet Sun are observed to evolve coherently, interacting with each other to form distinguished structures as they are advected by the horizontal photospheric flows. We study coherent structures in photospheric flows in a region of quiet Sun consisted of supergranules. Supergranular turbulence is investigated by detecting hyperbolic and elliptic Lagrangian coherent structures (LCS) using the horizontal velocity fields derived from Hin…
Aims. We aim to characterise the magnetism of a large fraction of the north polar region close to a maximum of activity, when the polar regions are reversing their dominant polarity. Methods. We make use of full spectropolarimetric data from the CRisp Imaging Spectro-Polarimeter installed at the Swedish Solar Telescope. The data consist of a photospheric spectral line, which is used to infer the various physical parameters of different quiet Sun regions by means of the solution of the radiative transfer equation. We focus our analysis on the properties found for the north polar region and thei…
The relationship between chromospheric emissions and magnetic field strength
目标。分析了4台仪器的观测资料，研究了从温度最低区到色球中层高度的色球辐射与光球磁场的相关性。研究方法：数据包括伯克利-伊利诺伊-马里兰阵列（BIMA）的3.5 mm射电图像，TRACE的1600 A紫外图像，BBSO的Ca II K线滤波图和MDI/SOHO纵向光球磁图。第一次干涉毫米数据与目前最高的可用分辨率包括在这样的分析。我们确定强度图的各种参数，并将强度彼此关联并与磁场关联。结果如下：这里研究的色球诊断显示出它们的亮度结构有明显的相似性，并相对较好地绘制出了底层的光球磁场。我们发现一个幂律是一个很好的光球磁场和色球诊断在所有波长的发射之间的关系表示。色球亮度对磁场的依赖性在网络区和网络间区是不同的。
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of a quiet-Sun region at a wavelength of 3 mm, obtained during the first solar ALMA cycle on April 27, 2017, and compare them with available chromospheric observations in the UV and visible as well as with photospheric magnetograms. ALMA images clearly reveal the presence of distinct particularly dark/cool areas in the millimeter maps having temperatures as low as 60% of the normal quiet Sun at 3 mm, which are not seen in the other data. We speculate that ALMA is sensing cool chromospheric gas, whose presence had earli…
We benchmark new atomic data against a selection of irradiances obtained from medium-resolution quiet Sun spectra in the EUV, from 60 to 1040 Å. We use as a baseline the irradiances measured during solar minimum on 2008 April 14 by the prototype (PEVE) of the Solar Dynamics Observatory Extreme ultraviolet Variability Experiment (EVE). We take into account some inconsistencies in the PEVE data, using flight EVE data and irradiances we obtained from Solar & Heliospheric Observatory (SoHO) Coronal Diagnostics Spectrometer (CDS) data. We perform a differential emission measure and find overall exc…
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。
