LUCI (Lagrange eUv Coronal Imager) is a solar imager in the Extreme UltraViolet (EUV) that is being developed as part of the Lagrange mission, a mission designed to be positioned at the L5 Lagrangian point to monitor space weather from its source on the Sun, through the heliosphere, to the Earth. LUCI will use an off-axis two mirror design equipped with an EUV enhanced active pixel sensor. This type of detector has advantages that promise to be very beneficial for monitoring the source of space weather in the EUV. LUCI will also have a novel off-axis wide field-of-view, designed to observe the solar disk, the lower corona, and the extended solar atmosphere close to the Sun-Earth line. LUCI will provide solar coronal images at a 2-3 minute cadence in a pass-band centred on 19.5 nm. Observations made through this pass-band allow for the detection and monitoring of semi-static coronal structures such as coronal holes, prominences, and active regions; as well as transient phenomena such as solar flares, limb Coronal Mass Ejections (CMEs), EUV waves, and coronal dimmings. The LUCI data will complement EUV solar observations provided by instruments located along the Sun-Earth line such as PROBA2-SWAP, SUVI-GOES and SDO-AIA, as well as provide unique observations to improve space weather forecasts. Together with a suite of other remote-sensing and in-situ instruments onboard Lagrange, LUCI will provide science quality operational observations for space weather monitoring.
Initial radiometric calibration of the High-Resolution EUV Imager ($\textrm{HRI}_\textrm{EUV}$) of the Extreme Ultraviolet Imager (EUI) instrument onboard Solar Orbiter
Royal Observatory of Belgium（比利时皇家天文台）；Institut d’Astrophysique Spatiale, CNRS, Univ. Paris-Sud, Université Paris-Saclay（空间天体物理研究所，法国国家科学研究中心，巴黎南大学，巴黎萨克雷大学）；European Commission, DG Energy, Directorate D: Nuclear Energy, Safety and ITER（欧盟委员会，能源总司，D局：核能、安全与ITER）；Laboratoire Charles Fabry, Institut d’Optique Graduate School, Université Paris-Saclay（夏尔·法布里实验室，高等光学研究院，巴黎萨克雷大学）；Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center（达沃斯物理气象观测站，世界辐射中心）；UCL-Mullard Space Science Laboratory（伦敦大学学院-穆拉德空间科学实验室）；Centre Spatial de Liège, Université de Liège（列日航天中心，列日大学）；Max Planck Institute for Solar System Research（马克斯·普朗克太阳系研究所）
The extreme ultraviolet (EUV) observations are widely used in solar activity research and space weather forecasting since they can observe both the solar eruptions and the source regions of the solar wind. Flat field processing is indispensable to remove the instrumental non-uniformity of a solar EUV imager in producing high-quality scientific data from original observed data. Fengyun-3E (FY-3E) is a meteorological satellite operated in Sun-synchronous orbit, and the routine EUV imaging data from the Solar X-ray and Extreme Ultraviolet Imager (X-EUVI) onboard FY-3E has the characteristics of c…
We present here the kinematics of the EUV wave associated with a GOES M1.0-class solar flare, which originates in NOAA AR 12740. The event is thoroughly observed with Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO) with high spatio-temporal resolutions. This event displays many features of EUV waves, which are very decisive for the understanding of the nature of EUV waves. These features include: a fast-mode wave, a pseudo wave, a slow-mode wave and stationary fronts, probably due to mode conversion. One fast-mode wave also propagates towards the coronal hole situat…
In addition to X-rays, extreme ultraviolet (EUV) rays radiated from solar flares can cause serious problems, such as communication failures and satellite drag. Therefore, methods for forecasting EUV dynamic spectra during flares are urgently required. Recently, however, owing to the lack of instruments, EUV dynamic spectra have rarely been observed. Hence, we develop a new method that converts the soft X-ray light curve observed during large flare events into an EUV dynamic spectrum by using the Solar Dynamics Observatory / Atmospheric Imaging Assembly images, a numerical simulation, and atomi…
We report the smallest coronal jets ever observed in the quiet Sun with recent high resolution observations from the High Resolution Telescopes (HRI-EUV and HRI-Lyα) of the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter. In the HRI-EUV (174 Å) images, these microjets usually appear as nearly collimated structures with brightenings at their footpoints. Their average lifetime, projected speed, width, and maximum length are 4.6 min, 62 km s^(-1), 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs can be identified in some events. A subset of these events also …
Coronal waves are large-scale disturbances often driven by coronal mass ejections (CMEs). We investigate a spectacular wave event on 7 March 2012, which is associated with an X5.4 flare (SOL2012-03-07). By using a running center-median (RCM) filtering method for the detection of temporal variations in extreme ultraviolet (EUV) images, we enhance the EUV disturbance observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and the Sun Watcher using Active Pixel System detector and Image Processing (SWAP) onboard the PRoject for Onboard Autonomy 2 (PROBA2). …
Thermal Diagnostics with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory: A Validated Method for Differential Emission Measure Inversions
Two components of the coronal emission revealed by EUV spectroscopic observations
最近的光谱观测揭示了在日冕和过渡区形成的发射线的蓝向不对称性的普遍存在。这些不对称性是最突出的环路足点区域，在那里一个明确的相关性的不对称性与多普勒频移和线宽确定从单高斯fit. Such不对称建议至少有两个排放组件：占背景排放的主要组成部分和与高速上升流的次要组成部分。后者被认为在日冕加热过程中起着至关重要的作用，但对其性质尚未达成一致。在这里，我们稍微修改了最初开发的红-蓝（RB）不对称性分析技术，并将其应用于人造光谱和由Hinode上的EUV成像光谱仪观察到的光谱，并证明次级成分通常占总发射的百分之几，具有从50到150 km s-1的速度范围和高斯宽度相比，在环路足点区域的主要之一。RB不对称性分析的结果，然后用于指导双高斯拟合，我们发现，所获得的性能的第二个组成部分一般是一致的RB不对称性分析所获得的。通过比较的位置，相对强度和速度分布的蓝向二次分量的向上传播的扰动的属性显示在同步图像从大气成像组件板载的太阳动力学天文台，我们发现一个明确的关联的二次分量与传播的扰动。
Studies in the extreme ultraviolet (EUV) and X-ray ranges of the solar spectrum are important due to the active role of radiation of these ranges in the formation of the Earth's ionosphere. Photons of the EUV range are completely absorbed in the upper layers of the Earth's atmosphere and induce the excitation, dissociation, and ionization of its different components and, finally, the atmospheric heating. From the archive data of the EUV Variability Experiment of the Solar Dynamics Observatory (SDO/EVE), we formed series of diurnal values of the background fluxes radiated beyond flares in the E…
The Sun Coronal Ejection Tracker (SunCET) is an extreme ultraviolet imager and spectrograph instrument concept for tracking coronal mass ejections through the region where they experience the majority of their acceleration: the difficult-to-observe middle corona. It contains a wide field of view (0-4~\Rs) imager and a 1~Å spectral-resolution-irradiance spectrograph spanning 170-340~Å. It leverages new detector technology to read out different areas of the detector with different integration times, resulting in what we call "simultaneous high dynamic range", as opposed to the traditional high d…
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…
Extreme ultraviolet (EUV) solar flare emissions evolve in time as the emitting plasma heats and then cools. Although accurately modeling this evolution has been historically difficult, especially for empirical relationships, it is important for understanding processes at the Sun, as well as for their influence on planetary atmospheres. With a goal to improve empirical flare models, a new simple empirical expression is derived to predict how cool emissions will evolve based on the evolution of a hotter emission. This technique is initially developed by studying 12 flares in detail observed by t…
First observations of a dome-shaped large-scale coronal EUV wave
我们首次观测到圆顶形大规模极紫外日冕波，该波由STEREO-B上的EUVI仪器于2010年1月17日记录。认为观测到的结构是波穹的主要论点（而不是日冕物质抛射）是：a）穹丘外缘的球形形状和尖锐度以及穹丘内部观测到的喷发日冕物质抛射环; b）边缘上方的低日冕波信号与盘上的波信号完美连接; c）膨胀穹丘的横向范围远大于日冕变暗的范围; d）伴随的高频II型爆发表明在日冕低层形成激波。波穹向上膨胀的速度（$v \sim 650$ km s $^{-1}$）大于波的横向膨胀的速度（$v \sim 280$ km s $^{-1}$），表明波穹向上膨胀一直受到驱动，因此取决于日冕物质抛射的速度，而在横向上，在日冕物质抛射的横向膨胀停止后，波穹向上膨胀是自由传播的。我们还研究了扰动特性的演变：首先，扰动轮廓变陡，振幅增加。此后，振幅随r $^{-2.5 \pm 0.3}$减小，宽度变宽，扰动以下的积分保持不变。我们的研究结果与弱冲击快模MHD波的球形膨胀和衰减是一致的。
We use The Sun Watcher with Active Pixel System detector and Image Processing (SWAP) imager onboard the Project for Onboard Autonomy 2 (PROBA2) mission to study the evolution of large-scale EUV structures in the solar corona observed throughout Solar Cycle 24 (from 2010 to 2019). We discuss the evolution of the on-disk coronal features and at different heights above the solar surface based on EUV intensity changes. We also look at the evolution of the corona in equatorial and polar regions and compare them at different phases of the solar cycle, as well as with sunspot number evolution and wit…
Quadrature Observations of Wave and Non-Wave Components and Their Decoupling in an Extreme-Ultraviolet Wave Event
我们报告了2011年1月27日极紫外（EUV）波事件的正交观测结果，由极紫外成像仪（EUVI）机载\emph{Solar Terrestrial Relations Observatory}（\emph{STEREO}）和大气成像组件（AIA）机载\emph{Solar Dynamics Observatory}（\emph{SDO}）。在极紫外波事件中揭示了两个分量。以$\sim$ 440 km s $^{-1}$的初始速度发射主锋。在较热的通道中出现显著的排放增强，而在较冷的通道中出现深度排放减少。当主锋遇到一个大的日冕环系统并减速时，一个次要的更微弱的锋从主锋发出，具有相对较高的$\sim$ 550 km s $^{-1}$的起始速度。之后，两个波前独立地传播，分离度增加。主锋最后停在磁分界线上，而次锋在它消失之前行进得更远。此外，当次级锋到达时，会触发日珥的横向振荡。我们认为这两个组成部分具有不同的性质。主锋属于非波型日冕物质抛射（CME）分量，可以用场线拉伸模型合理解释。这种多温度行为可能是由于CME锋面环的非线性绝热压缩所引起的相当大的加热所造成的。对于次级锋，它很可能是一个线性快模磁流体（MHD）波，通过典型的日冕温度的介质传播。X射线和无线电数据为我们提供了支持上述情况的补充证据。
Investigation of the Formation and Separation of An EUV Wave from the Expansion of A Coronal Mass Ejection
我们通过直接观测由日冕物质抛射（CME）的膨胀及其随后从CME前沿分离驱动的漫射波的形成来解决EUV波的性质。2011年6月7日，太阳动力学天文台上的大气成像组件很好地观测到了波和CME。在太阳爆发开始之后，CME的速度和伴随耀斑的X射线通量开始迅速增加，CME表现出强烈的横向膨胀。在这个脉冲膨胀阶段，CME气泡的膨胀速度从100 km s $^{-1}$增加到450 km s $^{-1}$仅需6分钟。一个重要的发现是，扩散波前开始从前面的膨胀气泡后不久，横向膨胀放缓分离。此外，II型爆发形成的时间附近的分离。在分离之后，两个不同的锋以不同的运动学性质传播。漫射波前穿过整个太阳盘面，而尖锐的波前上升，形成CME喷出物，漫射波前在其前面。这些观测结果表明，以前称为EUV波是一种复合现象，由CME膨胀驱动。当日冕物质抛射加速膨胀时，波前与日冕物质抛射的波前是同空间的，因此这两个波前是不可分辨的。随着加速阶段的结束，波远离CME前沿，它们之间的距离逐渐增加。
We analyzed ground-based low frequency ($<$100\,MHz) radio spectral and imaging data of the solar corona obtained with the facilities in the Gauribidanur observatory during the same time as the very weak soft X-ray flares (sub A-class, flux $\rm {<}10^{-7}\,Wm^{-2}$ in the 1\,-\,8\,$\rm Å$ wavelength range) from the `quiet' Sun observed with the X-ray Solar Monitor (XSM) onboard Chandrayaan-2 during the recent solar minimum. Non-thermal type I radio burst activity were noticed in close temporal association with the X-ray events. The estimated brightness temperature ($T_{b}$) of the bursts at a…
Comparative Analysis of a Transition Region Bright Point with a Blinker and Coronal Bright Point Using Multiple EIS Emission Lines
自二十年前发现过渡区亮点以来，还从未在光谱上观测到过。亮点的性质还没有与类似的过渡区和日冕结构进行比较。在这项工作中，我们研究了三个瞬态安静的太阳增亮，包括TRBP，日冕BP（CBP）和闪光灯。我们使用时间序列观测的极紫外线发射线的温度T（log T = 5.3 - 6.4）从极紫外成像光谱仪（EIS）机载日之出卫星。我们提出的EIS温度图和多普勒地图，这是比较从迈克尔逊多普勒成像仪（MDI）的SOHO卫星上的磁图。TR BP和闪光灯的多普勒速度<，25 km s $^{-1}$，这是典型的瞬态TR现象。发现CBP的多普勒速度< 20 km s^{-1}，但在log T = 6.2时测得的速度除外，此时观察到明显的双向喷流。从EM位点分析，我们发现的证据，单和双等温组件的TRBP和CBP，分别。TRBP和CBP基因座曲线的特点是广泛的分布，表明存在未解决的结构。通过比较和对比事件的物理特性，我们发现BP现象是多尺度自相似性的指示，给出了它们的基本磁场配置和演化与EUV通量变化的相似性。相比之下，闪光现象和TRBP在其观察到的性质上足够不同，从而构成不同的事件类别。我们的工作表明，跨多个事件类型的相似特征的测量具有类别预测能力，并且是朝向未解析瞬态EUV源的自动化太阳大气多类别分类的重要一步。
Aditya-L1 and SDO Observations of a Confined X-Class Flare with an EUV Late Phase: Thermal and Nonthermal Emission, Magnetic Topology, and Flux Rope Confinement
Udaipur Solar Observatory, Physical Research Laboratory（乌代浦尔太阳观测站，物理研究实验室）；Discipline of Physics, Indian Institute of Technology Gandhinagar（甘地纳加尔印度理工学院物理系）；Physical Research Laboratory（物理研究实验室）
NASA, Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；The Catholic University of America（美国天主教大学）；University of Oslo（奥斯陆大学）；Frontier Development Lab（前沿发展实验室）；SETI Institute（SETI研究所）；Lockheed Martin Solar & Astrophysics Laboratory (LMSAL)（洛克希德·马丁太阳与天体物理实验室）；Université Paris-Saclay（巴黎萨克雷大学）；Institut d’astrophysique spatiale（空间天体物理研究所）；University of Oxford（牛津大学）
Solar activity plays a quintessential role in influencing the interplanetary medium and space-weather around the Earth. Remote sensing instruments onboard heliophysics space missions provide a pool of information about the Sun's activity via the measurement of its magnetic field and the emission of light from the multi-layered, multi-thermal, and dynamic solar atmosphere. Extreme UV (EUV) wavelength observations from space help in understanding the subtleties of the outer layers of the Sun, namely the chromosphere and the corona. Unfortunately, such instruments, like the Atmospheric Imaging As…
We present the Fermi-LAT observations of the behind-the-limb (BTL) flare of July 17, 2021 and the joint detection of this flare by STIX onboard Solar Orbiter. The separation between Earth and the Solar Orbiter was 99.2$^{\circ}$ at 05:00 UT, allowing STIX to have a front view of the flare. The location of the flare was ~S20E140 in Stonyhurst heliographic coordinates making this the most distant behind-the-limb flare ever detected in $>$100 MeV gamma-rays. The LAT detection lasted for $\sim$16 minutes, the peak flux was $ 3.6 \pm 0.8 $ (10$^{-5}$) ph cm$^{-2}$ s$^{-1}$ with a significance $>$15…
The Solar Orbiter mission, with an orbit outside the Sun Earth line and leaving the ecliptic plane, opens up opportunities for the combined analysis of measurements obtained by solar imagers and spectrometers. For the first time, different space spectrometers will be located at wide angles to each other, allowing three-dimensional (3D) spectroscopy of the solar atmosphere. The aim of this work is to prepare the methodology to facilitate the reconstruction of 3D vector velocities from two stereoscopic LOS Doppler velocity measurements using the Spectral Imaging of the Coronal Environment (SPICE…
Observations of the off-limb corona with the SWAP wide-field telescope in the 174\,Å passband onboard the PROBA2 mission provide an opportunity to study post-eruptive processes in the dimming regions. We investigate morphology, temporal evolution, and plasma properties for four `deep' off-disk coronal dimmings associated with limb coronal mass ejections (CMEs) in 2010\,--\,2017. Using the SWAP fixed-difference images, we revealed ray-like structures that appeared in the dimming recovery phase stretching quasi-radially to distances from 1.1 to 1.6\,$\mathrm{R}_{\odot}$ and existing from tens of…
Magnetic energy is required to heat the corona, the outer atmosphere of the Sun, to millions of degrees. We study the nature of the magnetic energy source that is probably responsible for the brightening of coronal loops driven by nanoflares in the cores of solar active regions. We consider observations of two active regions (ARs), 11890 and 12234, in which nanoflares have been detected. To this end, we use ultraviolet (UV) and extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) for coronal loop diagnostics. These images are…
