远程增亮（RB）是磁环足点处的紧凑增亮，这些磁环远程连接并约束太阳大气中的一次爆发。在此，我们报告对一次由速度约为90 km s^-1的EUV喷流产生的RB的观测。连接RB与喷流的磁环表观长度约为59 Mm。有趣的是，该RB至少呈现两期增亮，其特征表现为光变曲线中的两个峰值。维持RB第一和第二个峰值的能量分别为6.3×10^26 erg和8.4×10^26 erg，并在总能量中占据显著比例。RB增亮的第一个峰值与喷流峰值重合，时间延迟为12秒，而第二个峰值滞后108秒。除抛射流之外，我们还识别出另外两个源自爆发位置的流。其中一个相对较冷，温度为log_10 T/K=5.8–6.1，速度约为275±15 km s^-1。另一个较热，温度为log_10 T/K=7.0–7.3，传播速度快得多，约为750±70 km s^-1。我们将RB的第二个峰值直接归因于这种热流，而数值实验表明该热流是慢激波的结果。考虑到RB第一个峰值与爆发之间的极短时间延迟，我们推断第一期增亮由非热电子加热导致。我们的研究表明，RB中的动力学过程可为认识相应爆发的本质提供重要洞见，并有助于理解能量如何在整个太阳大气中分配。
英文摘要：
Remote brightening (RB) is compact brightening at footpoints of magnetic loops, which are remotely-connecting to and confining an eruption in the solar atmosphere. Here, we report on observations of an RB resulting from an EUV jet with a speed of about 90\,km\,s$^{-1}$. The loops connecting the RB and the jet have an apparent length of about 59\,Mm. Intriguingly, the RB exhibits at least two episodes of brightenings, as characterised by two peaks in its lightcurve. The energies, which sustain the first and second peaks of the RB, are $6.3\times10^{26}$\,erg and $8.4\times10^{26}$\,erg, respectively, and take a significant proportion of the total energy. The first peak of the RB brightenings coincides with the jet's peak with a time delay of 12 seconds, while the second peak lags behind by 108 seconds. Besides the flows of the ejecta, we have identified two additional flows originating from the eruption site. One is relatively cool with a temperature of $log_{10}T/K=5.8-6.1$ and has a speed of about $275\pm15$\,km\,s$^{-1}$. The other is hot with a temperature of $log_{10}T/K=7.0-7.3$ and travels much faster with a speed of about 750$\pm$\,70\,km\,s$^{-1}$. We attribute the second peak of RB directly to this hot flow, which our numerical experiments suggest is the result of a slow shock wave. Considering the minimal time delay between the first peak of RB and the eruption, we infer this first episode is due to heating by nonthermal electrons. Our research demonstrates that the dynamics in an RB can offer vital insights into the nature of the corresponding eruption and help understand how the energy is distributed throughout the solar atmosphere.
Accessing the fine temporal scale of EUV brightenings and their quasi-periodic pulsations: 1 second cadence observations by Solar Orbiter/EUI
Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium（太阳-地球卓越中心–SIDC，比利时皇家天文台）；Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven（荷语鲁汶大学数学系数学等离子体天体物理学中心）；Astronomy & Astrophysics Section, School of Cosmic Physics, Dublin Institute for Advanced Studies, DIAS Dunsink Observatory（都柏林高等研究院宇宙物理学院天文学与天体物理系，DIAS邓辛克天文台）；ETH-Zurich（苏黎世联邦理工学院）；Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center（达沃斯物理气象观测站，世界辐射中心）
A universal scaling between damping time and period of quasi-periodic pulsations from solar EUV brightenings to X-ray stellar flares
Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium（太阳-星际卓越中心–SIDC，比利时皇家天文台）；Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven（KU鲁汶大学数学系数学等离子体天体物理学中心）；University of Exeter（埃克塞特大学）；Centre for Fusion, Space and Astrophysics, Physics Department, University of Warwick（华威大学物理部聚变、空间与天体物理学中心）；Engineering Research Institute “Ventspils International Radio Astronomy Centre (VIRAC)”, Ventspils University of Applied Sciences（文茨皮尔斯应用科学大学“文茨皮尔斯国际射电天文中心（VIRAC）”工程研究所）；Centro de Investigacion en Astronomía, Universidad Bernardo O’Higgins（贝尔纳多·奥希金斯大学天文学研究中心）；Aryabhatta Research Institute of Observational Sciences (ARIES)（阿亚玻塔观测科学研究所（ARIES））
The High Resolution Imager (HRI_EUV) telescope of the Extreme Ultraviolet Imager (EUI) instrument onboard Solar Orbiter has observed EUV brightenings, so-called campfires, as fine-scale structures at coronal temperatures. The goal of this paper is to compare the basic geometrical (size, orientation) and physical (intensity, lifetime) properties of the EUV brightenings with regions of energy dissipation in a non-potential coronal magnetic field simulation. In the simulation, HMI line-of-sight magnetograms are used as input to drive the evolution of solar coronal magnetic fields and energy dissi…
这项工作的目的是确定瞬态EUV增亮的真正性质，称为闪光。共空间和共时间的多仪器数据，包括成像（EUVI/STEREO，XRT和SOT/Hinode），光谱（CDS/SoHO和EIS/Hinode）和磁图（SOT/Hinode）数据，一个孤立的赤道冕洞。应用CDSOV 629 A和EUVI 171 A的瞬态增亮自动识别程序.我们在CDS O V 629 A光栅图像中识别出28个闪光灯组。所有CDS O V 629 A眼罩均在EUVI 171 A和304 A图像中显示对应物。我们将这些闪光分为两类，一类与冠状对应物相关，另一类与XRT图像和EIS Fe XII 195.12 A光栅图像中所见的无冠状对应物相关。大约三分之二的闪光灯显示了日冕对应物，并对应于各种事件，如EUV/X射线喷流，日冕亮点的增亮或较大环的足点增亮。这些增亮重复发生，在过渡区温度下的寿命约为40分钟。在XRT和EIS Fe XII 195.12 A中没有日冕对应物的剩余闪烁群看起来像点状增亮，并且有色球/过渡区的起源。它们只发生一次，寿命约为20分钟。一般来说，闪光灯的寿命在不同的波长，即不同的温度下是不同的，从色球层到日冕逐渐减少。这项工作表明，术语blinker涵盖了一系列现象。闪烁是起源于日冕、过渡区和色球高度的各种瞬态事件的EUV响应。因此，与闪光灯相关的事件有助于形成和维持过渡区和日冕中的温度梯度。
Synchronic coronal hole mapping using multi-instrument EUV images: Data preparation and detection method
我们描述了一种使用同时多仪器EUV成像数据自动绘制冕洞（CH）的方法。对来自STEREO/EUVI A & B 195 A和SDO/AIA 193 A的同步EUV图像进行预处理，包括PSF去卷积和应用数据导出的强度校正，该校正考虑了中心到边缘的变化（边缘增亮）和仪器间强度归一化。我们系统地推导出一个强大的肢体增亮校正，利用无偏的长期平均数据，并尊重问题的物理性质。新的预处理大大有助于CH检测，允许使用一个简化的可变连接双阈值区域生长图像分割算法，以获得一致的检测结果。我们生成同步EUV和CH地图，并显示CH演变的初步分析。几个数据和代码产品提供给社区（www.predsci.com/chd）：在本研究期间（2010年6月10日至2014年8月18日），我们提供了同步EUV和冕洞地图数据，6小时的节奏，数据衍生的边缘增亮校正STEREO/EUVI A & B 195A和SDO/AIA 193A，以及仪器间校正因子，以等同于它们的强度。我们还提供了冕洞图像分割代码模块（ezseg）实现在两个FORTRAN的OpenMP和GPU加速的C-CUDA。我们还提供了一个完整的冕洞检测管道的实现，它是一个利用ezseg的即用型MATLAB驱动程序脚本euv2chm。
Context. Accurate detections of frequent small-scale extreme ultraviolet (EUV) brightenings are essential to the investigation of the physical processes heating the corona. Aims. We detected small-scale brightenings, termed campfires, using their morphological and intensity structures as observed in coronal EUV imaging observations for statistical analysis. Methods. We applied a method based on Zernike moments and a support vector machine classifier to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and SDO/AIA. Results. This method detecte…
The 3D fine structure of the solar atmosphere is still not fully understood as most of the available observations are taken from a single vantage point. The goal of the paper is to study the 3D distribution of small-scale brightening events ("campfires") discovered in the EUV quiet Sun by the Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter. We used a first commissioning data set acquired by the EUI's High Resolution EUV telescope on 30 May 2020 in the 174 Å passband and we combined it with simultaneous data taken by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observa…
Early Evolution of an Energetic Coronal Mass Ejection and Its Relation to EUV Waves
我们研究了与X级耀斑相关的一次日冕物质抛射（CME），它的起源在低日冕中被高节奏、高分辨率的EUV图像清楚地观测到，这为我们提供了一个难得的机会来详细地见证高能CME的早期演化。喷发开始于活动区外围的类似喷流的事件之后，冷却的覆盖环（~1 MK）缓慢膨胀。在扩展环路系统的下方，在热EUV通带中的增亮有源区的正上方看到反向S形调光。变暗与上升的弥漫拱（~6 MK）有关，我们将其解释为预先存在的高通量绳。这是其次由双热通道（~10 MK）从有源区的核心出现。较高的结构比较低的结构上升得更早、更快，其前沿经历了高达35 km s $^2$的极快加速度。这表明，环面的不稳定性是主要的喷发机制，它是高的平躺通量绳，而不是热通道，驱动喷发。日冕等离子体的压缩，裙和覆盖在扩大的环系统，其纵横比$h/r$随着时间的增加，作为一个快速的向上加速的结果，在驱动向外传播的全球EUV波和向日传播的本地EUV波，分别起着重要的作用。
Brightenings observed in the solar extreme-ultraviolet (EUV) images are generally interpreted as signatures of micro- or nanoflares occurring at the transition region or coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (termed campfires) in the quiet-Sun corona. Analyzing EUI 174 Å data at a resolution of about 400 km on the Sun with a cadence of 5 s from 30-May-2020, we report here a number of cases where these campfires exhibit propagating signatures along their apparent small (3-5 Mm) l…
We examine in greater detail five events previously identified as being sources of strong transient coronal outflows in a solar polar region in Hinode/EUV Imaging Spectrometer (EIS) Doppler data. Although relatively compact or faint and inconspicuous in Hinode/Soft X-ray Telescope (XRT) soft-X-ray (SXR) images and in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) EUV images, we find that all of these events are consistent with being faint coronal X-ray jets. The evidence for this is that the events result from eruption of minifilaments of projected sizes spanning 5000 -- 1…
Surprisingly Large Doppler Shifts in Hinode EUV Imaging Spectrometer (EIS) Solar Spectra, Resulting from an Inconspicuous Small-scale Jet in EUV Images
Nature of the energy source powering solar coronal loops driven by nanoflares
需要磁能来加热日冕，太阳的外层大气，达到数百万度。我们研究的性质的磁能源，这可能是负责在太阳活动区的核心纳米耀斑驱动的日冕环的增亮。我们考虑观察两个活跃的区域（AR），11890和12234，在其中已检测到nanoflars。为此，我们使用紫外线（UV）和极紫外线（EUV）的图像从大气成像组件（AIA）板载太阳动力学天文台（SDO）的日冕循环诊断。这些图像与SDO上的日震和磁成像仪（HMI）的同时视线磁场图相结合，以研究日冕环与光球层磁根之间的连接。这些AR的核心在AIA的多个EUV通道中表现出环路增亮，特别是在其9.4 nm滤光片中。HMI磁场标测图显示在这些环底部存在复杂的混合极性磁场分布。我们在这些位置检测到光球磁通量的抵消率约为$10^{15}$ Mx s $^{-1}$。直接在抵消磁特征上方的相关致密日冕增亮指示由于色球磁重联而导致的等离子体加热。我们认为，复杂的磁拓扑结构和磁场的演变，如在光球和由此产生的色球重联通量抵消，可以发挥重要的作用，在激励活动区日冕环驱动的纳米耀斑。我们估计在安静的太阳通量抵消过程中释放的磁能表明，色球重联也可以为安静的日冕提供动力。
The second Hi-C flight (Hi-C2.1) provided unprecedentedly-high spatial and temporal resolution ($\sim$250km, 4.4s) coronal EUV images of Fe IX/X emission at 172 Å, of AR 12712 on 29-May-2018, during 18:56:21-19:01:56 UT. Three morphologically-different types (I: dot-like, II: loop-like, III: surge/jet-like) of fine-scale sudden-brightening events (tiny microflares) are seen within and at the ends of an arch filament system in the core of the AR. Although type Is (not reported before) resemble IRIS-bombs (in size, and brightness wrt surroundings), our dot-like events are apparently much hotter,…
The goal of this paper is to study the smallest brightening events observed in the EUV quiet Sun. We use commissioning data taken by the EUI instrument onboard the recently launched Solar Orbiter mission. On 2020 May 30, EUI was situated at 0.556AU from the Sun. Its HRIEUV telescope 17.4nm passband reached an exceptionally high two-pixel spatial resolution of 400km. The size and duration of small-scale structures is determined in the HRIEUV data, while their height is estimated from triangulation with the simultaneous SDO/AIA data. This is the first stereoscopy of small scale brightenings at h…
Energy release from impacting prominence material following the 2011 June 7 eruption
太阳暗条表现出一系列类似喷发的动态活动，从暗条质量和周围磁结构的全部或部分喷发（如日冕物质抛射（CME））到完全受限或“失败”的喷发。2011年6月7日，SDO和STEREO上的多台仪器观察到一个巨大的丝状体部分喷发。这一事件的一个有趣的方面是太阳大气层的反应，因为在重力的影响下，非逃逸物质向内下落。撞击地点显示出明显的证据，表明由于能量释放，观测到的极紫外波长变亮。两个合理的物理机制解释的增亮被认为是：加热的等离子体由于压缩等离子体的撞击材料的动能，或低线圈的磁场和碰撞材料所携带的字段之间的重连。通过分析几个SDO/AIA波长的增亮发射，并将撞击物质的动能（7.6 x 10^26 - 5.8 x 10^27尔格）与辐射能（1.9 x 10^25 - 2.5 x 10^26尔格）进行比较，我们发现，在观测到的增亮中，能量释放的主要机制是等离子体压缩。
Weak heating events are frequent and ubiquitous in solar corona. They derive their energy from the local magnetic field and form a major source of local heating, signatures of which are seen in EUV and X-ray bands. Their radio emission arise from various plasma instabilities that lead to coherent radiation, making even a weak flare appear very bright. The radio observations hence probe non-equilibrium dynamics providing complementary information on plasma evolution. However, a robust study of radio emission from a weak event among many simultaneous events, requires high dynamic range imaging a…
Context: On 2020 May 30, small and short-lived EUV brightenings were observed in the Quiet Sun (QS) during a four minutes sequence by EUI/HRIEUV on board Solar Orbiter. Their physical origin and possible impact on coronal or Transition Region (TR) heating are still to be determined. Aims: Our aim is to derive the statistical thermal evolution of these events in order to establish their coronal or TR origin. Methods. Our thermal analysis takes advantage of the multithermal sensitivity of the Atmospheric Imaging Assembly (AIA) imager on board the Solar Dynamics Observatory (SDO). We first identi…
Recently nonthermal radio transients from the quiet sun have been discovered and it has been hypothesised using rough calculations that they might be important for coronal heating. It is well realized that energy calculations using coherent emissions are often subject to poorly constrained parameters and hence have large uncertainties associated with them. However energy estimates using observations in the extreme ultraviolet (EUV) and soft X-ray bands are routinely done and the techniques are pretty well established. This work presents our first attempt to identify the EUV counterparts of the…
Using ALMA observations, we performed the first systematic survey for transient brightenings (i.e. weak, small-scale episodes of energy release) in the quiet solar chromosphere at 3 mm. Our dataset included images of six 87'' x 87'' regions of the quiet Sun obtained with angular resolution of a few arcsec at a cadence of 2 s. The transient brightenings were detected as weak enhancements above the average intensity after we removed the effect of the p-mode oscillations. A similar analysis, over the same regions, was performed for simultaneous 304 and 1600 Å data obtained with the Atmospheric Im…
High-resolution observations of small-scale activity in coronal hole plumes
Max Planck Institute for Solar System Research（马克斯·普朗克太阳系研究所）；Institut für Sonnenphysik (KIS)（太阳物理研究所）；Institut für Geophysik und extraterrestrische Physik, Technische Universität Braunschweig（不伦瑞克工业大学地球物理学与系外物理研究所）
We present a multi-instrument study of the two precursor brightenings prior to the M6.5 flare (SOL2015-06-22T18:23) in the NOAA Active Region 12371, with a focus on the temperature (T), electron number density (n), and emission measure (EM). The data used in this study were obtained from four instruments with a variety of wavelengths, i.e., the Solar Dynamics Observatory's Atmospheric Imaging Assembly (AIA), in six extreme ultraviolet (EUV) passbands; the Expanded Owens Valley Solar Array (EOVSA) in microwave (MW); the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in hard X-ray…
Emerging dimming occurs in isolated solar active regions (ARs) during the early stages of magnetic flux emergence. Observed by the Atmospheric Imaging Assembly, it features a rapid decrease in extreme-ultraviolet (EUV) emission in the 171 Å channel images, and a simultaneous increase in the 211 Å images. Here, we analyze the coronal thermodynamic and magnetic properties to probe its physical origin. We calculate the time-dependent differential emission measures for a sample of 18 events between 2010 and 2012. The emission measure (EM) decrease in the temperature range $5.7 \le \log_{10}T \le 5…
With high-resolution narrowband He I 10830 Å filtergrams from GST, we give an extensive analysis for 4 granular sized microeruptions which appear as the gentle ejection of material in He I 10830 Å band. The analysis was aided with the EUV data from AIA and line-of-sight magnetograms from HMI on board SDO. The microeruptions are situated on magnetic polarity inversion lines (PILs), and their roots are accurately traced down to intergranular lanes. Their durations are different, two microeruptions are repetitive microjets, lasting ~ 50 and 27 minutes respectively, while the other two events are …
Using EUV images and line-of-sight magnetograms from Solar Dynamics Observatory, we examine eight emerging bipolar magnetic regions (BMRs) in central-disk coronal holes for whether the emerging magnetic arch made any noticeable coronal jets directly, via reconnection with ambient open field as modeled by Yokoyama and Shibata (1995). During emergence, each BMR produced no obvious EUV coronal jet of normal brightness, but each produced one or more faint EUV coronal jets that are discernible in AIA 193 Å images. The spires of these jets are much fainter and usually narrower than for typical EUV j…
Formation of Transient Coronal Holes during Eruption of a Quiescent Filament and its Overlying Sigmoid
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。
Dynamics of Coronal Bright Points as seen by Sun Watcher using Active Pixel System detector and Image Processing (SWAP), Atmospheric Imaging Assembly AIA), and Helioseismic and Magnetic Imager (HMI)
\textit{PRoject for OnBoard Autonomy\todash 2}（PROBA \todash 2）航天器上的\textit{Sun Watcher using Active Pixel system detector and Image Processing}（SWAP）提供了以174 ° C为中心的极紫外通道中的日冕图像。这些数据与\textit{Solar Dynamics Observatory}（SDO）上的\textit{Atmospheric Imaging Assembly}（AIA）和\textit{Helioseismic and Magnetic Imager}（HMI）一起用于研究日冕亮点的动力学。的磁极性的演变和相关的形态变化进行了研究，使用磁图和多波长成像。在低分辨率SWAP图像和高分辨率AIA图像中看到的亮点的形态显示出不同的结构，而强度随时间的变化在SWAP 174和AIA 171通道中显示出相似的趋势。我们观察到，在对应于$10^{18}$ Mx量级的磁通量的EUV通道中看到亮点。我们发现，在几个紫外\todash EUV通道的亮点的总发射和总的无符号光球磁通量超过一定的阈值之间存在着良好的相关性。亮点也显示出周期性的增亮，我们试图找到亮点的振荡周期及其与磁通量变化的联系。观测到的周期一般都很长（10 \todash-25…
