We analyzed a long duration flare observed in a serendipitous XMM-Newton detection of the M star CD-39 7717B (TWA 11B), member of the young stellar association TW Hya (~ 8 Myr). Only the rise phase (with a duration of ~ 35 ks) and possibly the flare peak were observed. We took advantage of the high count-rate of the X-ray source to carry out a detailed analysis of its spectrum during the whole exposure. After a careful analysis, we interpreted the rise phase as resulting from the ignition of a first group of loops (event A) which triggered a subsequent two-ribbon flare (event B). Event A was analyzed using a single-loop model, while a two-ribbon model was applied for event B. Loop semi-lengths of ~ 4 R* were obtained. Such large structures had been previously observed in very young stellar objects (~ 1 - 4 Myr). This is the first time that they have been inferred in a slightly more evolved star. The fluorescent iron emission line at 6.4 keV was detected during event B. Since TWA 11B seems to have no disk, the most plausible explanation found for its presence in the X-ray spectrum of this star is collisional - or photo- ionization. As far as we are concerned, this is only the third clear detection of Fe photospheric fluorescence in stars other than the Sun.
AstroSat observations of long-duration X-ray superflares on active M-dwarf binary EQ Peg
We present a comprehensive study of three large long-duration flares detected on an active M-dwarf binary EQ Peg using the Soft X-Ray Telescope of the AstroSat observatory. The peak X-ray luminosities of the flares in the 0.3 - 7 keV band are found to be within ~5 - 10 x 10^{30} erg s^{-1}. The e-folding rise- and decay-times of the flares are derived to be in the range of 3.4 - 11 and 1.6 - 24 ks, respectively. Spectral analysis indicates the presence of three temperature corona with the first two plasma temperatures remain constant during all the flares and the post-flare observation at ~3 a…
A Statistical Study to Determine the Origin of Long-Duration Gamma-ray Flares
已经提出了两种方案来解释太阳耀斑中持续的$\ge 30$ \，MeV伽马射线发射：（1）长时间的粒子加速/捕获，涉及耀斑现场的大规模磁环，（2）高能（$>$ 300 MeV）质子在日冕/行星际冲击波加速的沉淀。为了确定哪种情况更有可能，我们检查了相关的软X射线耀斑，日冕物质抛射（CME）和太阳高能质子事件（SEP）：（a）由\Fermi上的大面积望远镜观测到的长时间伽马射线耀斑，和（b）太阳峰年任务中伽马射线分光仪观测到的延迟和/或空间扩展的高能伽马射线耀斑，伽马卫星上的伽马-1望远镜和康普顿伽马射线天文台上的高能伽马射线实验望远镜。对于11个持续$\ge \sim 2$小时的100 MeV $>$发射的LDGRF数据集，我们寻找LDGRF，X射线耀斑，CME和SEP之间的关联和反向关联，即，从γ射线耀斑开始，依次是X级软X射线耀斑，快速（$\ge$ 1500 km s $^{-1}$）和宽CME，以及强烈（峰值通量$\ge 2.67 \times 10^{-3}$ cm $^{-2}$ s $^{-1}$ sr $^{-1}$，峰值与背景比$>$ 1.38）$>$ 300 MeV SEP，1 A. U。虽然LDGRF往往与明亮的X级耀斑，我们发现，只有1/3的X级耀斑期间的\Fermi监测符合LDGRF。然而，几乎所有的快速，广泛的日冕物质抛射与LDGRF。这些初步的关联分析有利…
The 2024 July 16 Solar Event: A Challenge To The Coronal Mass Ejection Origin Of Long-Duration Gamma-Ray Flares
NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）；Catholic University of America（美国天主教大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究所比萨分部）；Jeremiah Horrocks Institute, University of Lancashire（兰开夏大学杰里米·霍罗克斯研究所）；W.W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University（斯坦福大学W.W.汉森实验物理实验室、卡弗里粒子天体物理学与宇宙学研究所、物理系及SLAC国家加速器实验室）；Department of Astronomy, University of Maryland, College Park（马里兰大学天文学系）；Space Science Center, University of New Hampshire（新罕布什尔大学空间科学中心）
A new analysis of the short-duration, hard-spectrum GRB 051103, a possible extragalactic SGR giant flare
GRB 051103被认为是一个候选的软伽马中继（SGR）河外巨磁星耀斑凭借其在天空中的接近M81/M82，以及它的时间历史，本地化和能谱。我们已经推导出一个完善的行星际网络本地化，这减少了超过两个因素的错误框的大小。我们检查其时间历史的证据，周期性的组件，这将是一个签名的SGR巨大的耀斑，并得出结论，这一组件既不是检测到，也不能检测到合理的假设。我们用改进的时间和能量分辨率分析了这一事件的时间分辨能谱，并得出结论，虽然谱是非常硬的，但它在后期的时间演化无法确定，这进一步复杂化了巨大的耀斑协会。我们还提出了新的光学观测，达到了R > 24.5的极限星等，比以前报道的要深4个星等。与M81爆发前和爆发后一个月的偶然观测相结合，这些观测对M81附近精确误差椭圆区域内的任何快速变化源都有很强的约束。我们没有找到任何令人信服的余辉候选人无论是从背景星系或来源在M81，虽然在改进的误差区域内，我们找到两个紫外线明亮的恒星形成区域，可能主机SGR。误差椭圆内的超新星遗迹（SNR）可以为SGR巨型耀斑协会提供进一步的支持，但我们无法确定误差椭圆内的任何SNR。这些数据仍然不允许对GRB 051103前身的性质进行严格的限制，并表明候选的河外SGR巨型耀斑将很难确认，尽管不是不可能。
Comparative Statistical Analysis of Prompt and Afterglow X-Ray Flares in Gamma-Ray Bursts: Insights into Extended Central Engine Activity
Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University（北京师范大学前沿天体物理研究院）；School of Physics and Astronomy, Beijing Normal University（北京师范大学物理与天文学院）
Mapping the Landscape of M Dwarf X-ray Flares: New Discoveries in Context
Bar-Ilan University（巴伊兰大学）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Weizmann Institute of Science（魏茨曼科学研究所）；University of Hamburg（汉堡大学）；Texas Tech University（德克萨斯理工大学）
A Multiwavelength Study of a Long-Duration VHE Flare from BL Lacertae with VERITAS
CP3-Origins, University of Southern Denmark（南丹麦大学）；DePauw University（迪堡大学）；Temple University（天普大学）；University of Utah（犹他大学）；Washington University（华盛顿大学）；University of California, Los Angeles（加州大学洛杉矶分校）；California Polytechnic State University（加州州立理工大学）；Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz（加州大学圣克鲁兹分校粒子物理研究所及物理系）
Wind-powered afterglows of gamma-ray bursts: flares, plateaus and steep decays
伽马射线暴的余辉通常表现为耀斑、平台和强度突然下降：这些时间特征很难解释为来自前向激波。我们计算了早期GRB余辉的辐射特性，其中主要贡献来自于由长时间持续的中央发动机产生的超相对论（脉冲星样）风中传播的反向激波（RS）。遥感发射发生在快速冷却制度-这确保高辐射效率，并允许快速强度变化。我们证明：（1）弱风力（$\sim 10^{46}$ erg s $^{-1}$）可以再现余辉的平台期;（2）风的终止可以产生突然的急剧衰减;（3）风光度的轻微变化可以产生短持续时间的余辉耀斑。
Radiation-hydrodynamics of star-disc collisions: From system parameters to outflows and lightcurves
Institute of Physics of the Czech Academy of Sciences（捷克科学院物理研究所）；Department of Theoretical Physics and Astrophysics, Masaryk University（马萨里克大学理论与天体物理学系）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）
