Flares are dynamic events which involve rapid changes in coronal magnetic topology end energy release. Even if they may be localized phenomena, the magnetic disturbance at their origin may propagate and be effective in a larger part of the active region. We investigate the temporal evolution of a flaring active region with respect to the loops morphology, the temperature, and emission measure distributions. We consider $Hinode/XRT$ data of a the 2006 November 12th C1.1 flare. We inspect the evolution of the morphology of the flaring region also with the aid of TRACE data. XRT filter ratios are used to derive temperature and emission measure maps and evolution. The analyzed flare includes several brightenings. We identify a coherent sequence of tangled and relaxed loop structures before, during, and after the brightenings. Although the thermal information is incomplete because of pixel saturation at the flare peak, thermal maps show fine, evolving spatial structuring. Temperature and emission measure variations show up in great detail, and we are able to detect a secondary heating of larger loops close to the proper flaring region. Finally we estimate the amount of energy released in these flaring loops during the flare decay.
Comparison of Hinode/XRT and RHESSI detection of hot plasma in the non-flaring solar corona
我们比较了观测的非耀斑太阳日冕同时与Hinode/XRT和RHESSI。2006年11月12日分析的日冕主要由一个单一的活动区。对排放措施进行了比较。我们推导出发射测量分布与温度的整个活动区从多滤波器XRT数据。我们检查的兼容性与总排放量的测量值估计的流量与RHESSI测量，如果排放来自等温等离子体。我们发现，RHESSI和XRT数据分析一致指向存在一个次要的排放测量组件峰值在log T ~ 6.8-6.9。XRT和RHESSI结果之间的差异在几个因素之内，表明交叉一致性的可接受水平。
In this paper we study the soft X-ray (SXR) signatures of one particular prominence. The X-ray observations used here were made by the Hinode/XRT instrument using two different filters. Both of them have a pronounced peak of the response function around 10 A. One of them has a secondary smaller peak around 170 A, which leads to a contamination of SXR images. The observed darkening in both of these filters has a very large vertical extension. The position and shape of the darkening corresponds nicely with the prominence structure seen in SDO/AIA images. First we have investigated the possibilit…
The target of this work is to investigate the physical nature of polar jets in the solar corona and their possible contribution to coronal heating and solar wind flow based on the analysis of X-ray images acquired by the Hinode XRT telescope. We estimate the different forms of energy associated with many of these small-scale eruptions, in particular the kinetic energy and enthalpy. Two Hinode XRT campaign datasets focusing on the two polar coronal holes were selected to analyze the physical properties of coronal jets; the analyzed data were acquired using a series of three XRT filters. Typical…
This study on plasma heating considers the time-dependent ionization process during a large solar flare on September 10, 2017, observed by Hinode/EIS. The observed FeXXIV / FeXXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electron temperature Te = 25 MK. Moreover, this study also shows that the non-thermal velocity, which can be related to the turbulent velocity, reduces significantly along the downstream of the reconnection outflow, even when considering the time-dependent ionization process.
NuSTAR is a highly sensitive focusing hard X-ray (HXR) telescope and has observed several small microflares in its initial solar pointings. In this paper, we present the first joint observation of a microflare with NuSTAR and Hinode/XRT on 2015 April 29 at ~11:29 UT. This microflare shows heating of material to several million Kelvin, observed in Soft X-rays (SXRs) with Hinode/XRT, and was faintly visible in Extreme Ultraviolet (EUV) with SDO/AIA. For three of the four NuSTAR observations of this region (pre-, decay, and post phases) the spectrum is well fitted by a single thermal model of 3.2…
Evidence of widespread hot plasma in a non-flaring coronal active region from Hinode/XRT
纳米耀斑，在空间上无法分辨的磁链中的短而强的热脉冲，现在被认为是解决日冕加热问题的主要候选者。然而，频繁出现的纳米耀斑要求耀斑热等离子体始终存在于日冕中。到目前为止，它的探测被证明是难以捉摸的，部分原因是预测的强度非常微弱。在这里，我们报告的一个活跃的区域观察到的5个过滤器的日之出/XRT在2006年11月的分析。我们已经使用的过滤器比率的方法来获得软，硬比率的温度和排放量的地图。这些图是近似的，因为等离子体被假设为沿着每个视线是等温的。尽管如此，最难的可用比率揭示了约10 MK的血浆的明显存在。为了获得更详细的等离子体特性的信息，我们进行了蒙特卡罗模拟假设各种非等温发射测量分布沿视线。我们发现，所观察到的过滤器的比率意味着双峰分布组成的一个强冷（log T ~ 6.3-6.5）的组件和较弱（百分之几）和较热（6.6 < log T < 7.2）的组件。数据与沿所有视线的双峰分布一致，即，整个活跃区域。我们还发现，从过滤器的比率推断的等温温度敏感地依赖于冷组件的精确温度。该分量的轻微偏移可能导致热分量在硬比率测量中被遮蔽。因此，以硬比率和软比率制作的温度图往往是反相关的。我们的结论是，这一观察结果支持存在广泛的nanoflaring活动的活跃区域。
In this paper we describe observations acquired by satellite instruments (Hinode/SOT and IRIS) and ground-based telescopes (ROSA@DST) during two consecutive C7.0 and X1.6 flares occurred in active region NOAA 12205 on 2014 November 7. The analysis of these data show the presence of continuum enhancements during the evolution of the events, observed both in ROSA images and in IRIS spectra. Moreover, we analyze the role played by the evolution of the $δ$ sunspots of the active region in the flare triggering, indicating the disappearance of a large portion of penumbra around these sunspots.
We investigate seven eruptive plasma observations by Hinode/XRT. Their corresponding EUV and/or white light CME features are visible in some events. Five events are observed in several passbands in X-rays, which allows the determination of the eruptive plasma temperature using a filter ratio method. We find that the isothermal temperatures vary from 1.6 to 10 MK. These temperatures are an average weighted toward higher temperature plasma. We determine the mass constraints of eruptive plasmas by assuming simplified geometrical structures of the plasma with isothermal plasma temperatures. This m…
In the present work we study Hinode/EIS observations of an active region taken before, during and after a small C2.0 flare in order to monitor the evolution of the magnetic field evolution and its relation to the flare event. We find that while the flare left the active region itself unaltered, the event included a large Magnetic Field Enhancement (MFE), which consisted of a large increase of the magnetic field to strengths just short of 500~G in a rather small region where no magnetic field was measured before the flare. This MFE is observed during the impulsive phase of the flare at the foot…
Three homologous C-class flares and one last M-class flare were observed by both the Solar Dynamics Observatory (SDO) and the Hinode EUV Imaging Spectrometer (EIS) in the AR 11429 on March 9, 2012. All the recurrent flares occurred within a short interval of time (less than 4 hours), showed very similar plasma morphology and were all confined, until the last one when a large-scale eruption occurred. The C-class flares are characterized by the appearance, at approximatively the same locations, of two bright and compact footpoint sources of $\approx$~3--10~MK evaporating plasma, and a semi-circu…
The physical properties and its contribution to the onset of solar flare are still unclear although chromospheric brightening is considered a precursor phenomenon of flare. Many studies suggested that photospheric magnetic field changes cause destabilization of large-scale coronal structure. We aim to understand how a small photospheric change contributes to a flare and to reveal how the intermediary chromosphere behaves in the precursor phase. We analyzed the precursor brightening of the X1.6 flare on 2014 October 22 in the AR 12192 using the Interface Region Imaging Spectrograph (IRIS) and H…
We present the study of the X2-class flare which occurred on the 27 October 2014 and was observed with the Interface Region Imaging Spectrograph (IRIS) and the EUV Imaging Spectrometer (EIS) on board the Hinode satellite. Thanks to the high cadence and spatial resolution of the IRIS and EIS instruments, we are able to compare simultaneous observations of the \xxi~1354.08~Å~and \xxiii~263.77~Å~high temperature emission ($\gtrsim$ 10~MK) in the flare ribbon during the chromospheric evaporation phase. We find that IRIS observes completely blue-shifted \xxi~line profiles, up to 200 km s$^{-1}$ dur…
To understand the conditions that produce white-light (WL) enhancements in solar flares, a statistical analysis of visible continuum data as observed by Hinode/Solar Optical Telescope (SOT) was performed. In this study, approximately 100 flare events from M- and X-class flares were selected. The time period during which the data were recorded spans from January 2011 to February 2016. Of these events, approximately half are classified as white-light flares (WLFs), whereas the remaining events do not show any enhancements of the visible continuum (non-WLF; NWL). In order to determine the existen…
Emission Height and Temperature Distribution of White-Light Emission Observed by Hinode/SOT from the 2012 January 27 X-class Solar Flare
2012年1月27日，利用日之出卫星上的太阳光学望远镜的三个连续谱带（红、绿、蓝）观测到了X1.7级太阳耀斑的白光发射。这一事件发生在太阳边缘附近，因此不同发射源的位置差异与不同发射源在光球层上方的高度差异一致。在这种解释下，我们的观察结果与发生在Ca II H发射发生的最低水平的白光发射是一致的。此外，白光发射的红色、绿色和蓝色波长的源区的中心彼此显著移位，这表明这些相应的发射是从太阳大气中逐渐降低的高度发出的。温度分布也从白光数据计算，我们发现较低层的发射有一个较高的温度。这表明高能粒子向下穿透到光球层附近，并将热量沉积到周围的大气下层。
Rapid Enhancement of Sheared Evershed Flow Along the Neutral Line Associated with an X6.5 Flare Observed by Hinode
本文介绍了2006年12月6日由Hinode/SOT获得的NOAA AR 10930的G波段和Ca II H观测结果，其中包括一个X6.5耀斑。采用局部相关跟踪（LCT）技术，对经透视缩短校正的G波段图像序列进行处理，获取了该复杂的β-γ-δ活动区的水平自行。利用连续的高质量、空间和时间分辨率的G波段数据，我们不仅证实了外半影的快速衰减和中心结构在耀斑中性线附近的变暗，而且第一次明确地检测到剪切Evershed流的增强，（平均水平流速从330 ± 3.1 m/s增加到403 ± 4.6 m/s）。耀斑后的Ca II H图像表明，原本在中性线两侧呈扇形分布的场线被连接起来。由于半影结构和Evershed流与光球磁倾角或水平场强度密切相关，我们将黑子结构和表面流的快速变化解释为耀斑引起的磁场重组的结果。磁场由向外成扇形变为向内连接，导致外半影衰减，同时，在耀斑中性线附近的磁场变得更加水平，导致那里的Evershed流更强。中性线附近水平磁场增强的推断与最近的磁观测和耀斑引起的光球磁场变化的理论预测是一致的。
We analyzed high-cadence sit-and-stare observations acquired with the Hinode/EIS spectrometer and HXR measurements acquired with RHESSI during an M-class flare. During the flare impulsive phase, we observe no significant flows in the cooler Fe XIII line but strong upflows, up to 80-150 km/s, in the hotter Fe XVI line. The largest Doppler shifts observed in the Fe XVI line were co-temporal with the sharp intensity peak. The electron density obtained from a Fe XIII line pair ratio exhibited fast increase (within two minutes) from the pre-flare level of 5.01x10^(9) cm^(-3) to 3.16x10^(10) cm^(-3)…
Rapid Disappearance of Penumbra-Like Features Near a Flaring Polarity Inversion Line: The Hinode Observations
我们观测到耀斑区极性反转线附近的半影状特征。PIL位于活动区的护城河边界（NOAA 10960）。PLFs在形态上与太阳黑子半影相似，但面积较小，约为6 $\times10^{7}$ km $^{2}$，与太阳黑子或太阳黑子孔隙不相关。我们观察到一个C1.7级耀斑后，PLF的快速消失，这发生在PIL附近。这些特征的局部相关跟踪（LCT）显示了远离PLF端点的水平流的存在，类似于在规则太阳黑子周围发现的径向向外流，这也被称为护城河流。在RHESSI观测中发现了与PLF位置一致的硬X射线发射，这表明耀斑的发生与PLF的衰变之间存在空间相关性。由日野分光偏振仪SOT/SP观测得到的耀斑前后的矢量磁场表明，耀斑后磁场的水平分量和垂直分量都发生了显著变化。耀斑间隔中磁场的两个分量的减弱表明，在耀斑间隔期间发生了PLF中磁场的快速消除和/或淹没。
An X1.6 flare occurred in AR 12192 on 2014 October 22 at 14:02 UT and was observed by Hinode, IRIS, SDO, and RHESSI. We analyze a bright kernel which produces a white light (WL) flare with continuum enhancement and a hard X-ray (HXR) peak. Taking advantage of the spectroscopic observations of IRIS and Hinode/EIS, we measure the temporal variation of the plasma properties in the bright kernel in the chromosphere and corona. We found that explosive evaporation was observed when the WL emission occurred, even though the intensity enhancement in hotter lines is quite weak. The temporal correlation…
One of the key processes associated with the "standard" flare model is chromospheric evaporation, a process where plasma heated to high temperatures by energy deposition at the flare footpoints is driven upwards into the corona. Despite several decades of study, a number of open questions remain, including the relationship between plasma produced during this process and observations of earlier "superhot" plasma. Hinode/EIS has a wide slot often used as a flare trigger in the He II emission line band. Once the intensity passes a threshold level, the study switches to one focussed on the flaring…
Hinode EIS Observations of Plasma Composition Evolution and Radiative Cooling of Solar Flare Loops
INAF Osservatorio Astronomico di Roma（罗马天文台）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；Universities Space Research Association（大学空间研究协会）；Mullard Space Science Laboratory, University College London（伦敦大学学院穆拉德空间科学实验室）；Northumbria University（诺森比亚大学）；Computational Physics Inc.（计算物理公司）；Dublin City University（都柏林城市大学）；Dublin Institute for Advanced Studies（都柏林高等研究院）；Konkoly Observatory（孔科利天文台）
We analyze the spectra of high temperature \fexxiv~lines observed by \emph{Hinode}/EIS during the impulsive phase of the X8.3--class flare on September 10, 2017. The line profiles are broad, show pronounced wings, and clearly depart from a single Gaussian shape. The lines can be well fitted with $κ$ distributions, with values of $κ$ varying between~$\approx$1.7 to 3. The regions where we observe the non-Gaussian profiles coincide with the location of high-energy ($\approx$100--300 keV) HXR sources observed by \emph{RHESSI}, suggesting the presence of particle acceleration or turbulence, also c…
We present direct evidence for the detection of the main energy release site in a non-eruptive solar flare, SOL2013-11-09T06:38UT. This GOES C2.7 event was characterised by two flaring ribbons and a compact, bright coronal source located between them, which is the focus of our study. We use imaging from SDO/AIA, and imaging spectroscopy from RHESSI to characterise the thermal and non-thermal emission from the coronal source, and EUV spectroscopy from the Hinode/EIS, which scanned the coronal source during the impulsive peak, to analyse Doppler shifts in Fe XII and Fe XXIV emission lines, and d…
We consider the observational basis for the belief that flare ribbons in the chromosphere result from energy transport from the overlying corona. We study ribbons of small flares using magnetic as well as intensity data from the Hinode, SDO and IRIS missions. While most ribbons appear connected to the corona, and they over-lie regions of significant vertical magnetic field, we examine one ribbon with no clear evidence for such connections. Evolving horizontal magnetic fields seen with Hinode suggest that reconnection with pre-existing fields below the corona can explain the data. The identific…
We present new constraints on the high-temperature emission measure of a non-flaring solar active region using observations from the recently flown Focusing Optics X-ray Solar Imager sounding rocket payload. FOXSI has performed the first focused hard X-ray (HXR) observation of the Sun in its first successful flight on 2012 November 2. Focusing optics, combined with small strip detectors, enable high-sensitivity observations with respect to previous indirect imagers. This capability, along with the sensitivity of the HXR regime to high-temperature emission, offers the potential to better charac…
Coherent Lateral Motion of Penumbral Filaments during X-class Flare
现在，对Hinode航天器搭载的天基50厘米太阳光学望远镜拍摄的太阳光球层高分辨率照片进行了例行观测。2006年12月13日，日野号拍摄了NOAA 10930中的三角洲黑子，当时该活动区发生了X级耀斑。两个明亮的丝带可见，即使在白光和G-波段的图像除了色球Ca II H图像。我们使用互相关技术对太阳黑子进行了全球登记，并分析了耀斑间隔期间的局部效应。我们发现在耀斑期间，半影暗条有横向运动。此外，我们定位两个补丁，一个在任何极性，这表明收敛运动的极性反转线（PIL）。在钙II H图像中，我们发现内核与耀斑前的增亮，位于沿PIL。
We assess the on-orbit performance of the flare event trigger for the Hinode EUV Imaging Spectrometer. Our goal is to understand the time-delay between the occurrence of a flare, as defined by a prompt rise in soft X-ray emission, and the initiation of the response observing study. Wide (266$''$) slit patrol images in the He II 256.32A spectral line are used for flare hunting, and a reponse is triggered when a pre-defined intensity threshold is reached. We use a sample of 13 $>$ M-class flares that succesfully triggered a response, and compare the timings with soft X-ray data from GOES, and ha…
We have reviewed the first year of observations of the Solar X-ray Monitor (XSM) onboard Chandrayaan-2, and the available multi-wavelength observations to complement the XSM data, focusing on Solar Dynamics Observatory AIA and Hinode XRT, EIS observations. XSM has provided disk-integrated solar spectra in the 1--15 keV energy range, observing a large number of microflares. We present an analysis of multi-wavelength observations of AR 12759 during its disk crossing. We use a new radiometric calibration of EIS to find that the quiescent AR core emission during its disk crossing has a distributio…
We analyse observations of the X9.3 solar flare (SOL2017-09-06T11:53) observed by SDO/HMI and Hinode/SOT. Our aim is to learn about the nature of the HMI pseudocontinuum Ic used as a proxy for the white-light continuum. From model atmospheres retrieved by an inversion code applied to the Stokes profiles observed by the Hinode satellite we synthesise profiles of the FeI 617.3 nm line and compare them to HMI observations. Based on a pixel-by-pixel comparison we show that the value of Ic represents the continuum level well in quiet-Sun regions only. In magnetised regions it suffers from a simplis…
We present observations of a B7.9-class flare that occurred on the 24th January, 2015, using the Atmopsheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO), the EUV Imaging Spectrometer (EIS) and the X-Ray Telescope of Hinode. The flare triggers the eruption of a dense cool plasma blob as seen in AIA 171Å,\, which is unable to completely break out and remains confined within a local bundle of active region loops. During this process, transverse oscillations of the threads are observed. The cool plasma is then observed to descend back to the chromosphere along each loop strand. …
