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Measurements of spectral lines observed with Hinode/EIS as implications for coronal heating

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Research in Astronomy and Astrophysics 2009年第7期9卷 829-840页

作者： Ying Li ming-de ding department of Astronomy Nanjing University Nanjing 210093 China

We have measured the line widths and nonthermal velocities in 12 solar regions using high resolution EUV data taken by Hinode/EIS. We find that there exists a positive correlation between the intensity and nonthermal velocity for the Fe xII emission line as well as some other lines. The correlation coefficients decrease from the disk center to the limb. However, the nonthermal velocities of a particular spectral line do not vary much in different regions, so they are considered isotropic. In particular, we find that for a coronal loop structure, the largest widths and nonthermal velocities occur at the footpoints, where outflows appear. Based on these observational results, we discuss several physical processes responsible for coronal heating.

关键词： line: profiles - Sun: corona - Sun: UV radiation

Interaction and eruption of two filaments observed by Hinode, SOHO, and STEREO

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Research in Astronomy and Astrophysics 2012年第3期12卷 287-299页

作者： Ying Li ming-de ding School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory for Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210093China

We investigate the interaction between two filaments and the subsequent filament eruption event observed from different viewing angles by Hinode, the Solar and Heliospheric Observatory, and the Solar Terrestrial Relations Observatory. In the event, the two filaments rose high, interacted with each other, and finally were ejected along two different paths. We measure the bulk-flow velocity using spectroscopic data. We find significant outflows at the speed of a few hundreds of km s 1 during the filament eruption, and also some downflows at a few tens of km s-1 at the edge of the eruption region in the late stage of the eruption. The erupting material was composed of plasmas with a wide temperature range of 10-4–106 K. These results shed light on the filament nature and the coronal dynamics.

关键词： line: profiles—Sun: corona—Sun: filaments—Sun: flares—Sun: UV radiation

Small-Scale Brightenings in the UV Continuum of an M9.1 Solar Flare

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 721-732页

作者： Lin Wang Cheng Fang ming-de ding department of Astronomy Nanjing University Nanjing 210093

We analyze an M9.1 two-ribbon solar flare which occurred on 2004 July 22 using the TRACE white-light and 1700 A images, the RHESSI, and the SOHO/MDI data. We find many small-scale fast-varying brightenings that appeared in the white-light and 1700 A images along the flare ribbons. Some of them underwent rapid motions in weak magnetic field regions. We identify these short-lived brightenings as UV continuum enhancement. Our preliminary result shows that the brightenings are closely related to the HXR emission. They have a lifetime of 30-60 s and a typical size of about 1＂-2＂. The intensity enhancement is about 150-200 times the mean value of the quiet-Sun. According to previous works, we infer that the 1700A enhancement may be dominated by the increased emission of 1680A continuum coming from the temperature minimum region. The impulsive feature in the 1700 A light curves of the small-scale brightenings may be due to the irradiation of the impulsive CIv line intensity caused by the bombardment of non-thermal electron beams.

关键词： Sun activity -- Sun flares -- Sun UV radiation

Can the temperature of Ellerman Bombs be more than 10 000 K？

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Research in Astronomy and Astrophysics 2017年第4期17卷 1-6页

作者： Cheng Fang Qi Hao ming-de ding Zhen Li School of Astronomy and Space Science Nanjing UniversityNanjing 210093China key laboratory of modern astronomy and astrophysics(nanjing university) ministry of education collaborative innovation center of modern astronomy and space exploration

Ellerman bombs （EBs） are small brightening events in the solar lower atmosphere. By their original definition, the main characteristic of EBs is the two emission bumps in both wings of chro- mospheric lines, such as Hα and Ca II 8542A lines. Up to now, most authors have found that the temperature increase of EBs around the temperature minimum region is in the range of 600-3000 K. However, with recent IRIS observations, some authors proposed that the temperature increase of EBs could be more than 10 000 K. Using non-LTE semi-empirical modeling, we investigate the line profiles, continuum emission and radiative losses for EB models with different temperature increases, and com- pare them with observations. Our result indicates that if the EB maximum temperature reaches more than 10000K around the temperature minimum region, then the resulting Hα and Call 8542A line profiles and the continuum emission would be much stronger than those of EB observations. Moreover, due to the high radiative losses, a high temperature EB compatible with observations. Thus, our study does not higher than 10 000 K. would have a very short lifetime, which is not support the proposal that EB temperatures are higher than 10 000 K.

关键词： line profiles -- Sun: photosphere -- Sun: chromosphere

Magnetic field changes associated with three successive M-class solar flares on 2002 July 26

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Research in Astronomy and Astrophysics 2011年第6期11卷 692-700页

作者： Pu Wang ming-de ding Hai-Sheng Ji Hai-Min Wang epartment of Astronomy Nanjing UniversityNanjing 210093China Purple Mountain Observatory Chinese Academy of SciencesNanjing 210008China Space Weather Research Lab Center for Solar Terrestrial ResearchNew Jersey Institute of TechnologyNewarkNJ 07102US

With an extensive analysis,we study the temporal evolution of magnetic flux during three successive M-class flares in two adjacent active regions：NOAA 10039 and *** primary data are full disk longitudinal magnetograms observed by SOHO/*** three flares are observed to be accompanied by magnetic flux *** changes occurred immediately or within 1 ～ 10 minutes after the starting time of the flares,indicating that the changes are obvious consequences of the solar *** changes in many points are intrinsic in magnetic flux,for some sites,it is caused by a rapid expansion motion of magnetic *** the second flare,the associated change is more gradual compared with the ＇step-function＇ reported in ***,we use the data observed by the Imaging Vector Magnetograph（IVM） at Mees Solar Observatory to check possible line profile changes during the *** results from the IVM data confirm the flux changes obtained from the MDI data.A series of line profiles were obtained from the IVM＇s observations and analyzed for flux change *** find that the fluctuations in the width,depth and central wavelength of the lines are less than 5.0 even at the flare＇s *** line profile change is observed during or after the *** conclude that the magnetic field changes associated with the three solar flares are not caused by flare emission.

关键词： Sun:activity-Sun:magnetic field-Sun:flares

Radiative hydrodynamic simulations of the spectral characteristics of solar white-light flares

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Research in Astronomy and Astrophysics 2021年第1期21卷 1-14页

作者： Yu-Tong Yang Jie Hong Ying Li ming-de ding Hui Li Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210033China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China

As one of the most violent activities in the solar atmosphere,white-light flares(WLFs)are generally known for their enhanced white-light(or continuum)emission,which primarily originates in the solar lower ***,we know little about how white-light emission is *** this study,we aim to investigate the response of the continua at 3600Åand 4250Åand also the Hαand Lyαlines during WLFs modeled using radiative hydrodynamic *** take non-thermal electron beams as the energy source for the WLFs in two different initial atmospheres and vary their *** results show that the model with non-thermal electron beam heating clearly shows enhancements in the continua at 3600Åand 4250Åas well as in the Hαand Lyαlines.A larger electron beam flux,a smaller spectral index,or an initial penumbral atmosphere leads to a stronger emission increase at 3600Å,4250Åand in the Hα*** Lyαline,however,is more obviously enhanced in a quiet-Sun initial atmosphere with a larger electron beam spectral *** is also notable that the continua at 3600Åand 4250Åand the Hαline exhibit a dimming at the start of heating and reach their peak emissions after the peak time of the heating function,while the Lyαline does not show such *** results can serve as a reference for the analysis of future WLF observations.

关键词： methods:numerical radiative transfer Sun:atmosphere Sun:flares

Energy spectral property in an isolated CME-driven shock

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Research in Astronomy and Astrophysics 2016年第2期16卷 105-112页

作者： Xin Wang Yi-Hua Yan ming-de ding Na Wang Hao Shan Xinjiang Astronomical Observatory Chinese Academy of Sciences Key Laboratory of Solar Activity National Astronomical Observatories Chinese Academy of Sciences Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Key Laboratory of Radio Astronomy Chinese Academy of Sciences

Observations from multiple spacecraft show that there are energy spectral ＂breaks＂ at 1-10 MeV in some large CME-driven shocks. However, numerical models can hardly simulate this property due to high computational expense. The present paper focuses on analyzing these energy spectral ＂breaks＂ by Monte Carlo particle simulations of an isolated CME-driven shock. Taking the 2006 dec 14 CME-driven shock as an example, we investigate the formation of this energy spectral property. For this purpose, we apply different values for the scattering time in our isolated shock model to obtain the highest energy ＂tails,＂ which can potentially exceed the ＂break＂ energy range. However, we have not found the highest energy ＂tails＂ beyond the ＂break＂ energy range, but instead find that the highest energy ＂tails＂ reach saturation near the range of energy at 5 MeV. So, we believe that there exists an energy spectral ＂cut off＂ in an isolated shock. If there is no interaction with another shock, there would not be formation of the energy spectral ＂break＂ property.

关键词： acceleration of particles -- shock waves -- Sun coronal mass ejections (CMEs) -- solar wind-- methods numerical

Preface:Advanced Space-based Solar Observatory(ASO-S)

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Research in Astronomy and Astrophysics 2019年第11期19卷 1-2页

作者： Wei-Qun Gan ming-de ding Yu Huang Ying-Na Su Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210034China School of Astronomy and Space Science Nanjing UniversityNanjing 210023China

The Advanced Space-based Solar Observatory(ASO-S)is the first approved solar space mission in *** special issue includes a total of 13 papers,which were selected from presentations at the First ASO-S International Workshop,held in Nanjing from 2019 January 15 to *** together,these 13 papers provide a complete description of ASO-S until the end of Phase-B and the beginning of Phase-C.

关键词： space vehicles instruments Sun magnetic fields flares CMEs UV radiation X-ray,gamma-rays

Some interesting topics provoked by the solar filament research in the past decade

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Research in Astronomy and Astrophysics 2020年第10期20卷 329-342页

作者： Peng-Fei Chen Ao-Ao Xu ming-de ding School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory of Modern Astronomy&Astrophysics Nanjing UniversityNanjing 210023China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao 999078China

Solar filaments are an intriguing phenomenon,like cool clouds suspended in the hot *** structures exist in the intergalactic medium as *** being a long-studied topic,solar filaments have continually attracted intensive attention because of their link to coronal heating,coronal seismology,solar flares and coronal mass ejections(CMEs).In this review paper,by combing through the solar filament-related work done in the past decade,we discuss several controversial topics,such as the fine structures,dynamics,magnetic configurations and helicity of *** high-resolution and highsensitivity observations,combined with numerical simulations,it is expected that resolving these disputes will definitely lead to a huge leap in understanding the physics related to solar filaments,and even shed light on galactic filaments.

关键词： Magnetohydrodynamics Sun:prominences Sun:filaments