We present an analysis of seven flares detected from five RS CVn-type binaries (UZ Lib, σGem, λAnd, V711 Tau and EI Eri) observed with XMM-Newton observatory. The quiescent state X-ray luminosities in the energy band of 0.3-10.0 keV of these stars were found to be 10^{30.7-30.9} erg/s. The exponential decay time in all the sample of flares range from ~ 1 to 8 hrs. The luminosity at peak of the flares in the energy band of 0.3-10.0 keV were found to be in the range of 10^{30.8} - 10^{31.8} erg/s. The great sensitivity of the XMM-EPIC instruments allowed us to perform time resolved spectral analysis during the flares and also in the subsquent quiescent phases. The derived metal abundances of coronal plasma were found to vary during the flares observed from σGem, V771 Tau and EI Eri. In these flares elemental abundances found to be enhanced by factors of ~ 1.3-1.5 to the quiescent states. In most of the flares, the peak temperature was found to be more than 100 MK whereas emission measure increased by factors of 1.5 - 5.5. Significant sustained heating was present in the majority of flares. The loop lengths (L) derived for flaring structure were found to be of the order of 10^{10 -11} cm and are smaller than the stellar radii (R*) i.e. L/R* \lesssim 1. The flare from σGem showed a high and variable absorption column density during the flare.
Accretion Disk Winds in AM CVn Binaries - a Monte Carlo Approach
AM CVn系统是类似激变变星(CV)的相互作用双星,但更紧凑,轨道周期小于80分钟。主星是一颗白矮星,而主星的性质还不完全清楚。通过分析吸积盘(由Nagel等人在这些会议上提出),可以发现次级星系外层的丰度和成分。从高状态AM CVn系统的光谱不仅显示典型的签名的吸积盘,但也P天鹅座线轮廓,流出的迹象存在于系统中。在这里,我们提出了第一个定量的光谱分析的吸积盘风在AM CVn系统。用我们的三维蒙特卡罗辐射转移程序WOMPAT模拟了出现的风谱。我们表明,P天鹅座配置文件可以复制与我们的风模型。
The New RS CVn Binary V1034 Her Revisited and the orbital period - Activity relation of Short-period RS CVn binaries using photometric distortion amplitude
A Possible Stellar CME Event Associated with a Long-duration Optical Flare on the RS CVn-type Star UX Arietis
International Centre of Supernovae (ICESUN), Yunnan Key Laboratory of Supernova Research, Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences(中国科学院天体结构与演化重点实验室);Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);School of Astronomy and Space Science, University of Chinese Academy of Sciences(中国科学院大学天文与空间科学学院)
Photometric investigation and orbital period analyses of the W UMa binaries FP Lyn, FV CVn and V354 UMa
给出了FP Lyn、FV CVn和V354 UMa的新光变曲线和光度解。发现这三个系统都是W型浅接触双星。此外,很明显,FP Lyn和V354 UMa的光变曲线是不对称的。因此,在主星FP Lyn上增加了一个热点,而在副星V354 UMa上增加了一个暗点。与此同时,我们在FP Lyn的光度解决方案中添加了第三盏灯,以获得最终结果。对于FP Lyn,获得的质量比和填充因子为$q=1.153$和$f=13.4\%$,对于FV CVn,获得的质量比和填充因子为$q=1.075$和$f=4.6\%$,对于V354 UMa,获得的质量比和填充因子为$q=3.623$和$f=10.7\%$。对这三个系统轨道周期的研究表明,它们的轨道周期是变化的。发现FP Lyn和V 354 Uma分别存在着长期增长的组分,其增长率分别为$dp/dt=4.19\times10^{-7}$ d yr $^{-1}$和$dp/dt=7.70\times10^{-7}$ d yr $^{-1}$,这可能是由质量较小的组分向质量较大的组分的守恒质量转移引起的。此外,还发现了FV CVn的一些可变成分,即频率为$dp/dt=-1.13\times10^{-6}$ d yr $^{-1}$,伴随着振幅和周期分别为0.0069天和10.65年的周期振荡。长期下降的最可能的解释是角动量损失。而附加分量的存在是对周期性变化的最合…
No Period Change in Two Long-Period AM CVn Binaries
University of Oklahoma(俄克拉荷马大学);University of Colorado and National Institute of Standards and Technology(科罗拉多大学和国家标准与技术研究院);University of Warwick(华威大学);Institute of Science and Technology Austria(奥地利科学技术研究所);University of Amsterdam(阿姆斯特丹大学);Carnegie Institution for Science(卡内基科学学会);Yunnan Observatories, CAS(中国科学院云南天文台);University of Cambridge(剑桥大学);University of Hamburg(汉堡大学);Liverpool John Moores University(利物浦约翰摩尔斯大学)
研究双长周期AM CVn双星Y Z LMi和Gaia14aae的食时变化,发现其轨道周期变化率一致为零,排除了额外角动量损失机制,限制了超高速引力波发射的可能。
JWST observations of three long-period AM CVn binaries: detection of the donors and hints of magnetically truncated disks
California Institute of Technology(加州理工学院);University of Oklahoma(俄克拉荷马大学);JILA, University of Colorado and National Institute of Standards and Technology(JILA,科罗拉多大学与美国国家标准与技术研究院);Massachusetts Institute of Technology(麻省理工学院)
A study of transients from ground-based surveys reveals new ultra-compact accreting white dwarf binaries
University of Texas Rio Grande Valley(德克萨斯大学里奥格兰德河谷分校);South Texas Space Science Institute, University of Texas Rio Grande Valley(德克萨斯大学里奥格兰德河谷分校南德克萨斯空间科学研究所);Texas Tech University(德克萨斯理工大学);Universidad Nacional Autónoma de México, Instituto de Astronomía(墨西哥国立自治大学天文学研究所);University of Michigan(密歇根大学);Institute of Science and Technology Austria(奥地利科学技术研究所)
X-ray and Hα superflare on an RS CVn-type star, UX Arietis: Constraint on the flare location from radial velocity change during the flare
Chuo University(中央大学);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(美利坚天主教大学);Kyoto University(京都大学);Subaru Telescope, National Astronomical Observatory of Japan(日本国立天文台昴星望远镜);University of Colorado Boulder(科罗拉多大学博尔德分校);National Solar Observatory(美国国家太阳观测台);Chiba University(千叶大学)
X-ray Activity of the RS CVn-type Star σ Gem with the First-Year Observations of Einstein Probe
National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台);School of Astronomy and Space Science, University of Chinese Academy of Sciences(中国科学院大学天文学院);INAF - Osservatorio Astronomico di Palermo(意大利国家天体物理研究所巴勒莫天文台);Department of Physics, Imperial College London(伦敦帝国理工学院物理系)
XRISM view of a stellar flare: High-resolution Fe K spectra of HR 1099, an RS CVn-type star
The University of Tokyo(东京大学);Japan Aerospace Exploration Agency, Institute of Space and Astronautical Science(日本宇宙航空研究开发机构宇宙科学研究所);NASA / Goddard Space Flight Center(美国国家航空航天局戈达德太空飞行中心);University of Geneva(日内瓦大学);Technion(以色列理工学院);Lawrence Livermore National Laboratory(劳伦斯利弗莫尔国家实验室);Center for Astrophysics, Harvard-Smithsonian(哈佛-史密森尼天体物理中心);SRON Netherland(荷兰苏诺空间研究所)
XRISM 观测到 HR 1099 耀斑,利用高分辨率 Fe K 光谱揭示了双峰 DEM 分布,发现钙和铁丰度在耀斑期间显著增加。
The evolutionary history of ultra-compact accreting binaries. I. Chemical abundances and formation channel of the eclipsing AM CVn system ZTF J225237.05-051917.4 from HST spectroscopy
Hamburg Observatory, University of Hamburg(汉堡天文台,汉堡大学);European Southern Observatory(欧洲南方天文台);Department of Physics and Astronomy, Texas Tech University(德克萨斯理工大学物理与天文学系);Department of Physics, University of Warwick(华威大学物理系);Institut für Theoretische Physik und Astrophysik, University of Kiel(基尔大学理论物理与天体物理研究所);São Paulo State University (UNESP), School of Engineering and Sciences(圣保罗州立大学(UNESP)工程与科学学院);The Observatories of the Carnegie Institution for Science(卡内基科学机构天文台);Department of Physics, University of California, Santa Barbara(加州大学圣塔芭芭拉分校物理系);Departamento de Física, Universidad Técnica Federico Santa María(费德里科·圣玛丽亚技术大学物理系);Institute of Science and Technology Austria(奥地利科学技术研究所);Anton Pannekoek Institute for Astronomy, University of Amsterdam(阿姆斯特丹大学安东·潘农克天文研究所)
Radio Properties of RS Canum Venaticorum Variables in VLASS and RACS
University of Alberta(阿尔伯塔大学);Clemson University(克莱姆森大学);University of Sydney(悉尼大学);University of Wisconsin-Milwaukee(威斯康星大学密尔沃基分校);Australian Telescope National Facility, CSIRO Astronomy and Space Science(澳大利亚望远镜国家设施,CSIRO天文学与空间科学)
A survey of ultra-compact high-state AM CVn binaries with ZTF and Gaia: New discoveries and observational constraints on Galactic space density
Kazan Federal University(喀山联邦大学);Department of Astronomy, California Institute of Technology(加利福尼亚理工学院天文系);Institut für Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Universität Tübingen(蒂宾根大学天文与天体物理研究所、开普勒天体与粒子物理中心);Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology(麻省理工学院卡弗里天体物理学与空间研究研究所);Anton Pannekoek Institute for Astronomy, University of Amsterdam(阿姆斯特丹大学安东·潘内库克天文学研究所);Institute of Science and Technology Austria(奥地利科学技术研究院)
Hunting for millimeter flares from magnetic reconnection in pre-main sequence spectroscopic binaries
最近对低质量主序前偏心光谱双星DQ Tau和V773 Tau A的观测表明,它们的毫米光谱偶尔会被来自非热发射过程的耀斑所主导。瞬时活动被认为是同步加速的性质,由强大的磁重联事件引起,当双星组件的单独磁性结构能够相互作用并被迫重组时,通常在近星点附近。我们进行了第一次系统的研究,毫米的变化对样本的12 PMS光谱双星的目的是表征扩散的耀斑之间的来源可能会遇到类似的interbination事件。源样本包括短周期,近距离的双星,拥有一个高的轨道偏心率或圆形轨道。利用IRAM 30米望远镜上的MAMBO 2阵列,我们在1.25毫米处进行了连续4夜的监测,在此期间,所有的高偏心率双星接近近星点。我们还获得了同步光学VRI测量,因为恒星重联事件和光学增亮之间经常观察到强烈的联系。UZ Tau E是唯一一个在毫米波长下被探测到的光源:它表现出显著的变化;它也是唯一一个同时发生强烈光学变化的光源。这颗双星在目前的样本中拥有最大的轨道偏心率,这是恒星间磁相互作用事件的一个预测因素。由于轨道参数和可变吸积活动与DQ Tau相似,UZ Tau E的毫米行为与DQ Tau碰撞磁层模型有许多相似之处。然而,仅根据我们的观测,我们无法确定这种变化是否是重复性的,或者它是否也可能是由于电离风中的可变自由-自由发射。