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Calibration procedures for the CHASE/HIS science data

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Science China(Physics,Mechanics & Astronomy) 2022年第8期65卷 10-17页

作者： Ye Qiu ShiHao Rao Chuan Li Cheng Fang mingde ding Zhen Li YiWei Ni WenBo Wang Jie Hong Qi Hao Yu Dai PengFei Chen XiaoSheng Wan Zhi Xu Wei You Yuan Yuan HongJiang Tao XianSheng Li YuKun He Qiang Liu School of Astronomy and Space Science Nanjing UniversityNanjing 210023China Key Laboratory for Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210023China Yunnan Observatories Chinese Academy of SciencesKunming 650216China Shanghai Institute of Satellite Engineering Shanghai 201109China Changchun Institute of Optics Fine Mechanics and PhysicsUniversity of Chinese Academy of SciencesChangchun 130033China

The Hα line is an important optical line in solar observations containing the information from the photosphere to the chromosphere. To study the mechanisms of solar eruptions and the plasma dynamics in the lower atmosphere, the Chinese Hα Solar Explorer(CHASE) was launched into a Sun-synchronous orbit on October 14, 2021. The scientific payload of the CHASE satellite is the Hα Imaging Spectrograph(HIS). The CHASE/HIS acquires, for the first time, seeing-free Hα spectroscopic observations with high spectral and temporal resolutions. It consists of two observational modes. The raster scanning mode provides full-Sun or region-of-interest spectra at Hα(6559.7-6565.9 ?) and Fe I(6567.8-6570.6 ?) wavebands. The continuum imaging mode obtains full-Sun photospheric images at around 6689 ?. In this paper, we present detailed calibration procedures for the CHASE/HIS science data, including the dark-field and flat-field correction, slit image curvature correction, wavelength and intensity calibration, and coordinate transformation. The higher-level data products can be directly used for scientific research.

关键词： space-based telescope solar physics chromosphere photosphere

Evolution of the Toroidal Flux of CME Flux Ropes during Eruption

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The Innovation 2020年第3期1卷 37-43页

作者： Chen Xing Xin Cheng mingde ding School of Astronomy and Space Science Nanjing UniversityNanjing 210046China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of EducationNanjing 210093China

Coronal mass ejections(CMEs)are large-scale explosions of the coronal magnetic field.It is believed that magnetic reconnection significantly builds up the core structure of CMEs,a magnetic flux rope,during the eruption.However,the quantitative evolution of the flux rope,particularly its toroidal flux,is still unclear.In this paper,we study the evolution of the toroidal flux of the CME flux rope for four events.The toroidal flux is estimated as the magnetic flux in the footpoint region of the flux rope,which is identified by a method that simultaneously takes the coronal dimming and the hook of the flare ribbon into account.We find that the toroidal flux of the CME flux rope for all four events shows a two-phase evolution:a rapid increasing phase followed by a decreasing phase.We further compare the evolution of the toroidal flux with that of the Geostationary Operational Environmental Satellites soft X-ray flux and find that they are basically synchronous in time,except that the peak of the former is somewhat delayed.The results suggest that the toroidal flux of the CME flux rope may be first quickly built up by the reconnection mainly taking place in the sheared overlying field and then reduced by the reconnection among the twisted field lines within the flux rope,as enlightened by a recent 3D magnetohydrodynamic simulation of CMEs.

关键词： SUN:CORONA SUN:CORONAL MASS EJECTIONS(CMES) SUN:FLARES

The Chinese Hα Solar Explorer(CHASE) mission: An overview

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Science China(Physics,Mechanics & Astronomy) 2022年第8期65卷 2-9页

作者： Chuan Li Cheng Fang Zhen Li mingde ding PengFei Chen Ye Qiu Wei You Yuan Yuan MinJie An HongJiang Tao XianSheng Li Zhe Chen Qiang Liu Gui Mei Liang Yang Wei Zhang WeiQiang Cheng JianXin Chen ChangYa Chen Qiang Gu QingLong Huang MingXing Liu ChengShan Han HongWei Xin ChangZheng Chen YiWei Ni WenBo Wang ShiHao Rao HaiTang Li Xi Lu Wei Wang Jun Lin YiXian Jiang LingJie Meng Jian Zhao School of Astronomy and Space Science Nanjing University Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education Shanghai Institute of Satellite Engineering Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Shanghai Academy of Spaceflight Technology China Center for Resources Satellite Data and Application China Aerospace Science and Technology Corporation Key and Special Project Center of China National Space Administration (CNSA)

The Chinese Hα Solar Explorer(CHASE), dubbed “Xihe”—Goddess of the Sun, was launched on October 14, 2021 as the first solar space mission of China National Space Administration(CNSA). The CHASE mission is designed to test a newly developed satellite platform and to acquire the spectroscopic observations in the Hα waveband. The Hα Imaging Spectrograph(HIS)is the scientific payload of the CHASE satellite. It consists of two observational modes: raster scanning mode and continuum imaging mode. The raster scanning mode obtains full-Sun or region-of-interest spectral images from 6559.7 to 6565.9 ? and from 6567.8 to 6570.6 ? with 0.024 ? pixel spectral resolution and 1 min temporal resolution. The continuum imaging mode obtains photospheric images in continuum around 6689 ? with the full width at half maximum of 13.4 ?. The CHASE mission will advance our understanding of the dynamics of solar activity in the photosphere and chromosphere. In this paper, we present an overview of the CHASE mission including the scientific objectives, HIS instrument overview, data calibration flow, and first results of on-orbit observations.

关键词： space-based telescope solar physics chromosphere photosphere

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日地L5太阳探测工程概述

上海航天（中英文） 2024年第3期41卷 9-16页

作者：方成丁明德陈鹏飞李川程鑫郭洋戴煜李臻南京大学天文与空间科学学院江苏南京210023

南京大学联合中国气象局、上海航天技术研究院等单位共同建议的日地L5太阳探测工程——“羲和二号”,将在国际上首次发射一颗人造探测器至日地系统第5个拉格朗日点,通过精测矢量磁场、揭示三维爆发和精准预警预报,解答“活动区磁场的产... 详细信息

南京大学联合中国气象局、上海航天技术研究院等单位共同建议的日地L5太阳探测工程——“羲和二号”,将在国际上首次发射一颗人造探测器至日地系统第5个拉格朗日点,通过精测矢量磁场、揭示三维爆发和精准预警预报,解答“活动区磁场的产生演化及其与太阳爆发的物理联系”和“太阳爆发的传播规律及其与灾害性空间天气的关系”这2个太阳物理和空间天气领域亟待解决的重大科学和应用问题。本文重点阐述“羲和二号”的科学与应用目标,简要介绍其科学载荷和初步方案。联合日地连线方向上的太阳探测,“羲和二号”的实施将开启我国太阳立体探测时代,拓展人类对太阳爆发机制的理解,为空间天气预警预报带来革命性突破。

关键词：太阳活动太阳磁场太阳耀斑日冕物质抛射日地关系

Origin and structures of solar eruptions Ⅰ: Magnetic flux rope

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Science China Earth Sciences 2017年第8期60卷 1383-1407页

作者： CHENG Xin GUO Yang ding mingde School of Astronomy and Space Science Nanjing University Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education

Coronal mass ejections(CMEs) and solar flares are the large-scale and most energetic eruptive phenomena in our solar system and able to release a large quantity of plasma and magnetic flux from the solar atmosphere into the solar wind. When these high-speed magnetized plasmas along with the energetic particles arrive at the Earth, they may interact with the magnetosphere and ionosphere, and seriously affect the safety of human high-tech activities in outer space. The travel time of a CME to 1 AU is about 1–3 days, while energetic particles from the eruptions arrive even earlier. An efficient forecast of these phenomena therefore requires a clear detection of CMEs/flares at the stage as early as possible. To estimate the possibility of an eruption leading to a CME/flare, we need to elucidate some fundamental but elusive processes including in particular the origin and structures of CMEs/flares. Understanding these processes can not only improve the prediction of the occurrence of CMEs/flares and their effects on geospace and the heliosphere but also help understand the mass ejections and flares on other solar-type stars. The main purpose of this review is to address the origin and early structures of CMEs/flares, from multi-wavelength observational perspective. First of all, we start with the ongoing debate of whether the pre-eruptive configuration, i.e., a helical magnetic flux rope(MFR), of CMEs/flares exists before the eruption and then emphatically introduce observational manifestations of the MFR. Secondly, we elaborate on the possible formation mechanisms of the MFR through distinct ways. Thirdly, we discuss the initiation of the MFR and associated dynamics during its evolution toward the CME/flare. Finally, we come to some conclusions and put forward some prospects in the future.

关键词：早期结构磁通量太阳系起源喷发日冕物质抛射磁化等离子体太阳耀斑

Origin and structures of solar eruptions Ⅱ: Magnetic modeling

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Science China Earth Sciences 2017年第8期60卷 1408-1439页

作者： GUO Yang CHENG Xin ding mingde School of Astronomy and Space Science Nanjing University Key Laboratory for Modern Astronomy and Astrophysics (Nanjing University) Ministry of Education

The topology and dynamics of the three-dimensional magnetic field in the solar atmosphere govern various solar eruptive phenomena and activities, such as flares, coronal mass ejections, and filaments/prominences. We have to observe and model the vector magnetic field to understand the structures and physical mechanisms of these solar activities. Vector magnetic fields on the photosphere are routinely observed via the polarized light, and inferred with the inversion of Stokes profiles. To analyze these vector magnetic fields, we need first to remove the 180° ambiguity of the transverse components and correct the projection effect. Then, the vector magnetic field can be served as the boundary conditions for a force-free field modeling after a proper preprocessing. The photospheric velocity field can also be derived from a time sequence of vector magnetic fields.Three-dimensional magnetic field could be derived and studied with theoretical force-free field models, numerical nonlinear force-free field models, magnetohydrostatic models, and magnetohydrodynamic models. Magnetic energy can be computed with three-dimensional magnetic field models or a time series of vector magnetic field. The magnetic topology is analyzed by pinpointing the positions of magnetic null points, bald patches, and quasi-separatrix layers. As a well conserved physical quantity,magnetic helicity can be computed with various methods, such as the finite volume method, discrete flux tube method, and helicity flux integration method. This quantity serves as a promising parameter characterizing the activity level of solar active regions.

关键词：拓扑结构太阳爆发流体动力学模型磁模型矢量磁场太阳活动区三维磁场起源

Probing the Production of Extreme-ultraviolet Late-Phase Solar Flares by Using the Model Enthalpy-Based Thermal Evolution of Loops

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Probing the Production of Extreme-ultraviolet Late-Phase Sol...

On the Development of Automotive Composite Material Rear Bumper Beam

第35届中国气象学会年会

作者： Yu Dai mingde ding School of Astronomy and Space Science Nanjing University Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of Education Key Laboratory of Space Weather National Center for Space Weather China Meteorological Administration

Recent observations in extreme-ultraviolet(EUV) wavelengths reveal an EUV late phase in some solar flares that is characterized by a second peak in warm coronal emissions(3 MK) several tens of minutes to a few hours after the soft X-ray(SXR) peak. Using the model enthalpy-based thermal evolution of loops(EBTEL), in this paper we numerically probe the production of EUV late-phase solar flares. Starting from two main mechanisms of producing the EUV late phase, i.e., long-lasting cooling and secondary heating, we carry out two groups of numerical experiments to study the effects of these two processes on the emission characteristics in late-phase loops. In either of the two processes an EUV late-phase solar flare that conforms to the observational criteria can be numerically synthesized. However, the underlying hydrodynamic and thermodynamic evolutions in late-phase loops are different between the two synthetic flare cases. The late-phase peak due to a long-lasting cooling process always occurs during the radiative cooling phase, while that powered by a secondary heating is more likely to take place in the conductive cooling phase. We then propose a new method for diagnosing the two mechanisms based on the shape of EUV late-phase light curves. Moreover, from the partition of energy input, we discuss why most solar flares are not EUV late flares. Finally, by addressing some other factors that may potentially affect the loop emissions, we also discuss why the EUV late phase is mainly observed in warm coronal emissions.

关键词： Sun: corona Sun: flares Sun:UV radiation

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On the Development of Automotive Composite Material Rear Bum...

A UNIFIED MODEL FOR SOLAR FLARES

2015中国汽车工程学会年会

作者： mingde ding Jiancai Liu Bo Liu Xiao Wang Tongguang Li Du Cao Changan Auto Global R&D Center

Recently weight reduction is increasingly needed in automotive industry to reduce energy consumption and air pollution.In this paper,development of composite material rear bumper beam（GMT,LFT-D,PC-PBT） are discussed,and the material properties,molding process,impact and strength analysis,test results,lightweight and overall costs of composite rear bumper beam are comprehensively analyzed.The result shows that composite material rear bumper beam can not only meet perfonnance requirement,but also can achieve weight reducing above 40%.Although the cost of GMT and LFT-D beam is a little higher than that of steel beam,the cost of LFT-D rear bumper beam is lower.In the future,composite rear beam bumper will have a more extensive application.

关键词： composite material rear bumper beam lightweight cost extensive application

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南京大学学报(自然科学) 1999年第4期35卷 496-499页

作者： Chen Pengfei Fang Cheng ding mingde Tang Yuhua (Department of Astronomy,Nanjing University,210093,Nanjing,PRC) 南京大学天文系江苏

We performed 2.5-dimensional numerical simulation for two cases,one with the the reconnection point at a high altitude,the other with the reconnection point at a low altitude.In the high-altitude case,the bright loop appears to rise for a long time,with its two footpoints separating and the field lines below the bright loop shrinking,which are all typical features of two-ribbon flares.In the low-altitude case,the bright loops cease rising only a short time after the impulsive phase of the reconnection and then become rather stable,which shows a large similarity to the compact flares.The results imply that the two types of solar flares,i.e.,the two-ribbon flares and the compact ones,might be unified into the same magnetic reconnection model,where the height of the reconnection point leads to the bifurcation.

关键词： Sun:flares-MHD-Sun:magnetic fields