The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic fie...The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic field,solar flares and coronal mass ejections(CMEs).Three payloads are deployed:the Full-disk vector Magneto Graph(FMG),the Lyman-αSolar Telescope(LST)and the Hard X-ray Imager(HXI).ASO-S will perform the first simultaneous observations of the photospheric vector magnetic field,non-thermal imaging of solar flares,and the initiation and early propagation of CMEs on a single platform.ASO-S is scheduled to be launched into a 720 km Sun-synchronous orbit in 2022.This paper presents an overview of the mission till the end of Phase-B and the beginning of Phase-C.展开更多
The Full-disk Magneto Graph(FMG),a payload onboard the Advanced Space Solar Observatory(ASO-S),will measure the vector magnetic field in the photosphere.The instrument consists of a frontwindow filter,a telescope,an L...The Full-disk Magneto Graph(FMG),a payload onboard the Advanced Space Solar Observatory(ASO-S),will measure the vector magnetic field in the photosphere.The instrument consists of a frontwindow filter,a telescope,an LCVR polarimeter,an image-stabilization system,a seven-stage tunable Lyot filter,a CMOS camera with 4096×4096 pixels and a pair of calibration/focus wheels.In this paper,we describe the design of the FMG instrument and provide a summary of test observations carried out with the FMG prototype.展开更多
The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength positi...The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength position,the relevant data-processing and the magnetic field calibrations based on the measured polarization signals at one single wavelength position.It is found that solar radial Doppler velocity,which can cause the spectral line to shift,is a disadvantageous factor for the linear calibration at one wavelength position.Observations at two symmetric wavelength positions may significantly reduce the wavelength shift effect(~75%),but simulations show that such polarization signals located at the solar limbs(e.g.,beyond the longitude range of±30°)are not free from the effect completely.In future work,we plan to apply machine learning techniques to calibrate vector magnetic fields,or employ full Stokes parameter profile inversion techniques to obtain accurate vector magnetic fields,in order to complement the linear calibration at the single wavelength position.展开更多
The Advanced Space-based Solar Observatory(ASO-S)is the first approved solar space mission in China.This special issue includes a total of 13 papers,which were selected from presentations at the First ASO-S Internatio...The Advanced Space-based Solar Observatory(ASO-S)is the first approved solar space mission in China.This 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 18.Taken together,these 13 papers provide a complete description of ASO-S until the end of Phase-B and the beginning of Phase-C.展开更多
太阳射电爆发(Solar Radio Burst,SRB)是太阳高能电子与背景等离子体相互作用产生的感应辐射现象,其多样的动力学谱类型及其复杂的精细结构反映了辐射源区磁等离子体结构状态丰富的物理信息,而相关辐射机制则是解读相关物理信息的关键工...太阳射电爆发(Solar Radio Burst,SRB)是太阳高能电子与背景等离子体相互作用产生的感应辐射现象,其多样的动力学谱类型及其复杂的精细结构反映了辐射源区磁等离子体结构状态丰富的物理信息,而相关辐射机制则是解读相关物理信息的关键工具.长期以来,在SRB辐射机制的研究中一直存在着争议不决的两种主要机制,即等离子体辐射机制和电子回旋脉泽(Electron Cyclotron Maser,ECM)辐射机制.近年来,针对传统的ECM辐射机制应用到SRB现象时遇到的一些主要困难,发展了由幂律谱电子低能截止驱动和包含快电子束自生阿尔文波效应的新型ECM驱动模型,并成功应用于解释各类不同SRB动力学谱的形成机制.基于这些新型的ECM辐射模型,系统地总结了ECM辐射机制在各种不同类型SRB现象中的应用,并对它们不同动力学谱结构的形成给出了一致统一的物理解释.展开更多
We summarize studies of helical properties of solar magnetic fields such as current helicity and twist of magnetic fields in solar active regions (ARs), that are observational tracers of the alpha-effect in the solar ...We summarize studies of helical properties of solar magnetic fields such as current helicity and twist of magnetic fields in solar active regions (ARs), that are observational tracers of the alpha-effect in the solar convective zone (SCZ). Information on their spatial distribution is obtained by analysis of systematic magnetographic observations of active regions taken at Huairou Solar Observing Station of National Astronomical Observatories of Chinese Academy of Sciences. The main property is that the tracers of the alpha-effect are antisymmetric about the solar equator. Identifying longitudinal migration of active regions with their individual rotation rates and taking into account the internal differential rotation law within the SCZ known from helioseismology, we deduce the distribution of the effect over depth. We have found evidence that the alpha-effect changes its value and sign near the bottom of the SCZ, and this is in accord with the theoretical studies and numerical simulations. We discuss other regularities which can be revealed by further analysis such as possible dependence on longitude, time, and magnetic field strength, etc.展开更多
塞曼效应是目前测量太阳磁场最主要的方法,但使用塞曼效应观测存在两个问题:测量到的矢量磁场中,垂直于视线方向的磁场(横场)方向存在180°不确定性;同时,横场的测量精度也要比沿视线方向的磁场(纵场)低一个量级.可以通过在不同的...塞曼效应是目前测量太阳磁场最主要的方法,但使用塞曼效应观测存在两个问题:测量到的矢量磁场中,垂直于视线方向的磁场(横场)方向存在180°不确定性;同时,横场的测量精度也要比沿视线方向的磁场(纵场)低一个量级.可以通过在不同的视线方向立体观测磁场去除180°不确定性并且提高太阳磁场横场的测量精度.重点讨论联合日地L5点和日地连线方向的观测提高横场测量精度的问题,同时通过模型建构与数据定量分析,得出横场误差的减小量.通过球面三角公式,求得地球和L5点磁场的坐标关系,由标准偏差传递公式得到修正后的地球处的测量误差;统计日震和磁场成像仪(Helioseismic and Magnetic Imager,HMI)观测到的太阳磁场误差的数据分布,模拟出两幅符合太阳磁场分布的数据,分别作为地球和L5点的误差图;结合地球和L5点数据,得出地球横场误差的修正数据并与原始横场数据进行对比,发现可以使地球处观测的黄道面上的横场误差降低为原来的17%左右.展开更多
A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on fi...A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.展开更多
磁场是太阳物理的第1观测量,当前太阳磁场观测研究正迈向大视场、高时空分辨率、高偏振测量精度以及空间观测的时代.中国首颗太阳观测卫星-先进天基太阳天文台(ASO-S)也配置了具有高时空分辨率、高磁场灵敏度的全日面矢量磁像仪(FMG)载...磁场是太阳物理的第1观测量,当前太阳磁场观测研究正迈向大视场、高时空分辨率、高偏振测量精度以及空间观测的时代.中国首颗太阳观测卫星-先进天基太阳天文台(ASO-S)也配置了具有高时空分辨率、高磁场灵敏度的全日面矢量磁像仪(FMG)载荷,针对FMG载荷的需求,讨论了大面阵、高帧频互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)图像传感器应用于太阳磁场观测的可行性.首先,基于滤光器型太阳磁像仪观测的原理,比较分析了目前CMOS图像传感器(可用的或是可选的两种快门模式)的特点,指出全局快门类型更适合FMG;其次搭建了CMOS传感器实验室测试系统,测量了CMOS图像传感器的像素增益及其分布规律;最后在怀柔太阳观测基地的全日面太阳望远镜上开展了实测验证,获得预期成果.在这些研究基础上,形成了FMG载荷探测器选型方向.展开更多
Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the...Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne VIII is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne VIII is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun.展开更多
Using a 2.5-dimensional ideal MHD model in Cartesian coordinates, weinvestigate the equilibrium properties of coronal magnetic flux ropes in background magnetic fieldsthat are completely closed. The background fields ...Using a 2.5-dimensional ideal MHD model in Cartesian coordinates, weinvestigate the equilibrium properties of coronal magnetic flux ropes in background magnetic fieldsthat are completely closed. The background fields are produced by a dipole, a quadrupole, and anoctapole, respectively, located below the photosphere at the same depth. A magnetic flux rope isthen launched from below the photosphere, and its magnetic properties, i.e., the annular magneticflux Φ_p and the axial magnetic flux Φ_z, are controlled by a single emergence parameter. Thewhole system eventually evolves into equilibrium, and the resultant flux rope is characterized bythree geometrical parameters: the height of the rope axis, the half-width of the rope, and thelength of the vertical current sheet below the rope. It is found that the geometrical parametersincrease monotonically and continuously with increasing Φ_p and Φ_z: no catastrophe occurs.Moreover, there exists a steep segment in the profiles of the geometrical parameters versus eitherΦ_p or Φ_z, and the faster the background field decays with height, the larger both the gradientand the growth amplitude within the steep segment will be.展开更多
太阳活动区是太阳大气中产生各种活动现象的区域,精确地检测和识别太阳活动区对理解太阳磁场的形成机制具有极为重要的科学意义.根据太阳活动区结构较为复杂的特点,基于尺度不变特征变换(Scale-Invariant Feature Transform,SIFT)和密...太阳活动区是太阳大气中产生各种活动现象的区域,精确地检测和识别太阳活动区对理解太阳磁场的形成机制具有极为重要的科学意义.根据太阳活动区结构较为复杂的特点,基于尺度不变特征变换(Scale-Invariant Feature Transform,SIFT)和密度峰值聚类(Clustering by Fast Search and Find of Density Peaks,DPC)算法的优越性,提出了一种太阳活动区的自动检测和识别方法.首先,对太阳动力学天文台(Solar Dynamics Observatory,SDO)日震和磁场成像仪(Helioseismic and Magnetic Imager,HMI)的纵向磁图进行对比度增强;然后采用SIFT方法提取出全日面磁图中的特征点;最后利用DPC算法将特征点进行聚类,从而自动检测和识别出太阳活动区.研究结果表明,SIFT和DPC算法相结合的方法可以在不需要人工交互的情况下准确地自动检测出太阳活动区.展开更多
Studies on the periodic variation and the phase relationship between different solar activity indicators are useful for understanding the long-term evolution of solar activity cycles.Here we report the statistical ana...Studies on the periodic variation and the phase relationship between different solar activity indicators are useful for understanding the long-term evolution of solar activity cycles.Here we report the statistical analysis of grouped solar flare(GSF) and sunspot number(SN) during the time interval from January 1965 to March 2009.We find that,(1) the significant periodicities of both GSF and SN are related to the differential rotation periodicity,the quasi-biennial oscillation(QBO),and the eleven-year Schwabe cycle(ESC),but the specific values are not absolutely identical;(2) the ESC signal of GSF lags behind that of SN with an average of 7.8 months during the considered time interval,which implies that the systematic phase delays between GSF and SN originate from the inter-solar-cycle signal.Our results may provide evidence about the storage of magnetic energy in the corona.展开更多
We propose a magnetic confinement nuclear fusion mechanism for the evolution of a solar flare in the solar atmosphere.The mechanism agrees with two observed characteristics of explosive flares and coronal mass ejectio...We propose a magnetic confinement nuclear fusion mechanism for the evolution of a solar flare in the solar atmosphere.The mechanism agrees with two observed characteristics of explosive flares and coronal mass ejections(CMEs) that have proved to be very difficult to explain with previous mechanisms:the huge enrichments of3 He and the high energy gamma ray radiation.The twisted magnetic flux rope is a typical structure during the solar flares,which is closely related to the solar active region that magnetic fields have almost complete control over the plasma.Consequently,the plasma inside the flux rope is heated to more than 1.0×107 K by an adiabatic compression process,and then the thermonuclear fusion can take place in the flux rope accompanied with high energy gamma rays.We utilize the time-dependent ideal 2.5-dimensional magnetohydrodynamic(MHD) simulation to demonstrate the physical mechanism for producing flares,which reveals three stages of flare development with the process of magnetic energy conversion and intense release during the solar flares and CMEs in the solar atmosphere.Furthermore,we discuss the relationship between magnetic reconnection and solar eruptions.展开更多
作为中国首颗综合性太阳探测卫星的先进天基太阳天文台(Advanced Space-based Solar Observatory,ASO-S)于北京时间2022年10月9日7时43分在酒泉卫星发射中心成功发射.扼要介绍ASO-S卫星提出的背景、卫星的研制历程、科学目标、载荷构成...作为中国首颗综合性太阳探测卫星的先进天基太阳天文台(Advanced Space-based Solar Observatory,ASO-S)于北京时间2022年10月9日7时43分在酒泉卫星发射中心成功发射.扼要介绍ASO-S卫星提出的背景、卫星的研制历程、科学目标、载荷构成、任务总体以及卫星研制的组织架构,并对卫星的运行和科学产出略作展望.展开更多
基金supported by the Strategic Priority Research Program on Space Science, Chinese Academy of Sciences (Grant Nos. XDA15320100, XDA15320102, XDA15320103, XDA15320104, XDA15320300 and XDA15052200)supported by the National Natural Science Foundation of China (Grant Nos. 11427803, U1731241, U1631242 and 11820101002)
文摘The Advanced Space-based Solar Observatory(ASO-S)is a mission proposed for the 25 th solar maximum by the Chinese solar community.The scientific objectives are to study the relationships between the solar magnetic field,solar flares and coronal mass ejections(CMEs).Three payloads are deployed:the Full-disk vector Magneto Graph(FMG),the Lyman-αSolar Telescope(LST)and the Hard X-ray Imager(HXI).ASO-S will perform the first simultaneous observations of the photospheric vector magnetic field,non-thermal imaging of solar flares,and the initiation and early propagation of CMEs on a single platform.ASO-S is scheduled to be launched into a 720 km Sun-synchronous orbit in 2022.This paper presents an overview of the mission till the end of Phase-B and the beginning of Phase-C.
基金China Aerospace Science and Technology Corporation, the NO.771 InstituteChina Academy of Engineering Physics+4 种基金Changchun Institute of Optics, Fine Mechanics and Physics, CASNational Space Science Center, CASShanghai Engineering Center for Microsatellites, CASPurple Mountain Observatory, CASsupported by Grants:XDA15320102, 11427901 and XDA15052200
文摘The Full-disk Magneto Graph(FMG),a payload onboard the Advanced Space Solar Observatory(ASO-S),will measure the vector magnetic field in the photosphere.The instrument consists of a frontwindow filter,a telescope,an LCVR polarimeter,an image-stabilization system,a seven-stage tunable Lyot filter,a CMOS camera with 4096×4096 pixels and a pair of calibration/focus wheels.In this paper,we describe the design of the FMG instrument and provide a summary of test observations carried out with the FMG prototype.
基金supported by the Strategic Priority Research Program on Space Science, the Chinese Academy of Sciences (Grant Nos. XDA15320302, XDA15052200 and XDA15320102)the National Natural Science Foundation of China (Grant Nos. 11773038, 11703042, U1731241, 11427901, 11427803, 11473039 and U1831107)the 13th Fiveyear Informatization Plan of the Chinese Academy of Sciences (Grant No. XXH13505-04)
文摘The Full-disk vector Magneto Graph(FMG)instrument will carry out polarization observations at one wavelength position of the Fe I 5324.179?spectral line.This paper describes how to choose this single wavelength position,the relevant data-processing and the magnetic field calibrations based on the measured polarization signals at one single wavelength position.It is found that solar radial Doppler velocity,which can cause the spectral line to shift,is a disadvantageous factor for the linear calibration at one wavelength position.Observations at two symmetric wavelength positions may significantly reduce the wavelength shift effect(~75%),but simulations show that such polarization signals located at the solar limbs(e.g.,beyond the longitude range of±30°)are not free from the effect completely.In future work,we plan to apply machine learning techniques to calibrate vector magnetic fields,or employ full Stokes parameter profile inversion techniques to obtain accurate vector magnetic fields,in order to complement the linear calibration at the single wavelength position.
文摘The Advanced Space-based Solar Observatory(ASO-S)is the first approved solar space mission in China.This 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 18.Taken together,these 13 papers provide a complete description of ASO-S until the end of Phase-B and the beginning of Phase-C.
文摘太阳射电爆发(Solar Radio Burst,SRB)是太阳高能电子与背景等离子体相互作用产生的感应辐射现象,其多样的动力学谱类型及其复杂的精细结构反映了辐射源区磁等离子体结构状态丰富的物理信息,而相关辐射机制则是解读相关物理信息的关键工具.长期以来,在SRB辐射机制的研究中一直存在着争议不决的两种主要机制,即等离子体辐射机制和电子回旋脉泽(Electron Cyclotron Maser,ECM)辐射机制.近年来,针对传统的ECM辐射机制应用到SRB现象时遇到的一些主要困难,发展了由幂律谱电子低能截止驱动和包含快电子束自生阿尔文波效应的新型ECM驱动模型,并成功应用于解释各类不同SRB动力学谱的形成机制.基于这些新型的ECM辐射模型,系统地总结了ECM辐射机制在各种不同类型SRB现象中的应用,并对它们不同动力学谱结构的形成给出了一致统一的物理解释.
基金Supported by the National Natural Science Foundation of China.
文摘We summarize studies of helical properties of solar magnetic fields such as current helicity and twist of magnetic fields in solar active regions (ARs), that are observational tracers of the alpha-effect in the solar convective zone (SCZ). Information on their spatial distribution is obtained by analysis of systematic magnetographic observations of active regions taken at Huairou Solar Observing Station of National Astronomical Observatories of Chinese Academy of Sciences. The main property is that the tracers of the alpha-effect are antisymmetric about the solar equator. Identifying longitudinal migration of active regions with their individual rotation rates and taking into account the internal differential rotation law within the SCZ known from helioseismology, we deduce the distribution of the effect over depth. We have found evidence that the alpha-effect changes its value and sign near the bottom of the SCZ, and this is in accord with the theoretical studies and numerical simulations. We discuss other regularities which can be revealed by further analysis such as possible dependence on longitude, time, and magnetic field strength, etc.
文摘塞曼效应是目前测量太阳磁场最主要的方法,但使用塞曼效应观测存在两个问题:测量到的矢量磁场中,垂直于视线方向的磁场(横场)方向存在180°不确定性;同时,横场的测量精度也要比沿视线方向的磁场(纵场)低一个量级.可以通过在不同的视线方向立体观测磁场去除180°不确定性并且提高太阳磁场横场的测量精度.重点讨论联合日地L5点和日地连线方向的观测提高横场测量精度的问题,同时通过模型建构与数据定量分析,得出横场误差的减小量.通过球面三角公式,求得地球和L5点磁场的坐标关系,由标准偏差传递公式得到修正后的地球处的测量误差;统计日震和磁场成像仪(Helioseismic and Magnetic Imager,HMI)观测到的太阳磁场误差的数据分布,模拟出两幅符合太阳磁场分布的数据,分别作为地球和L5点的误差图;结合地球和L5点数据,得出地球横场误差的修正数据并与原始横场数据进行对比,发现可以使地球处观测的黄道面上的横场误差降低为原来的17%左右.
基金the team at the McIntosh Archive project (a Boston College/NOAA/NCAR collaboration, funded by the NSF), based at NOAA National Centers for Environmental Information, for creating a digital archive of McIntosh Carrington maps and making it available online. R.M
文摘A filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with a coronal mass ejection(CME), which has an adverse effect on space weather. Hence,research on filaments has attracted much attention in the recent past. The tilt angle of active region(AR)magnetic bipoles is a crucial parameter in the context of the solar dynamo, which governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. Filaments always form over polarity inversion lines(PILs), so the study of tilt angles for these filaments can provide valuable information about generation of a magnetic field in the Sun. We investigate the tilt angles of filaments and other properties using McIntosh Archive data. We fit a straight line to each filament to estimate its tilt angle. We examine the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveals that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitudes separately. Investigations of temporal variation with filament number indicate that total filament number and low latitude filament number vary cyclically, in phase with the solar cycle. There are fewer filaments at high latitudes and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filaments with different latitude criteria.
文摘磁场是太阳物理的第1观测量,当前太阳磁场观测研究正迈向大视场、高时空分辨率、高偏振测量精度以及空间观测的时代.中国首颗太阳观测卫星-先进天基太阳天文台(ASO-S)也配置了具有高时空分辨率、高磁场灵敏度的全日面矢量磁像仪(FMG)载荷,针对FMG载荷的需求,讨论了大面阵、高帧频互补金属氧化物半导体(Complementary Metal Oxide Semiconductor,CMOS)图像传感器应用于太阳磁场观测的可行性.首先,基于滤光器型太阳磁像仪观测的原理,比较分析了目前CMOS图像传感器(可用的或是可选的两种快门模式)的特点,指出全局快门类型更适合FMG;其次搭建了CMOS传感器实验室测试系统,测量了CMOS图像传感器的像素增益及其分布规律;最后在怀柔太阳观测基地的全日面太阳望远镜上开展了实测验证,获得预期成果.在这些研究基础上,形成了FMG载荷探测器选型方向.
基金Hui Tian, Jian-Sen He, Bo Tan, and Shuo Yao are supported by the National Natural Science Foundation of China under Grants 40574078, 40336053 and40436015by the Beijing Education Project XK100010404+4 种基金the foundation Major Project of National Basic Research, under contract 2006CB806305Hui Tian is also supported by China Scholarship Council for his stay in the Max-Planck-Institut fr Sonnen system for schung in GermanyLi-Dong Xia is supported by the National Natural Science Foundation of China under Grant 40574064the Programme for New Century Excellent Talents in University (NCET)supported by DLR, CNES, NASA, and the ESA PRODEX programme (Swiss contribution).
文摘Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne VIII is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne VIII is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun.
基金Supported by the National Natural Science Foundation of China.
文摘Using a 2.5-dimensional ideal MHD model in Cartesian coordinates, weinvestigate the equilibrium properties of coronal magnetic flux ropes in background magnetic fieldsthat are completely closed. The background fields are produced by a dipole, a quadrupole, and anoctapole, respectively, located below the photosphere at the same depth. A magnetic flux rope isthen launched from below the photosphere, and its magnetic properties, i.e., the annular magneticflux Φ_p and the axial magnetic flux Φ_z, are controlled by a single emergence parameter. Thewhole system eventually evolves into equilibrium, and the resultant flux rope is characterized bythree geometrical parameters: the height of the rope axis, the half-width of the rope, and thelength of the vertical current sheet below the rope. It is found that the geometrical parametersincrease monotonically and continuously with increasing Φ_p and Φ_z: no catastrophe occurs.Moreover, there exists a steep segment in the profiles of the geometrical parameters versus eitherΦ_p or Φ_z, and the faster the background field decays with height, the larger both the gradientand the growth amplitude within the steep segment will be.
文摘太阳活动区是太阳大气中产生各种活动现象的区域,精确地检测和识别太阳活动区对理解太阳磁场的形成机制具有极为重要的科学意义.根据太阳活动区结构较为复杂的特点,基于尺度不变特征变换(Scale-Invariant Feature Transform,SIFT)和密度峰值聚类(Clustering by Fast Search and Find of Density Peaks,DPC)算法的优越性,提出了一种太阳活动区的自动检测和识别方法.首先,对太阳动力学天文台(Solar Dynamics Observatory,SDO)日震和磁场成像仪(Helioseismic and Magnetic Imager,HMI)的纵向磁图进行对比度增强;然后采用SIFT方法提取出全日面磁图中的特征点;最后利用DPC算法将特征点进行聚类,从而自动检测和识别出太阳活动区.研究结果表明,SIFT和DPC算法相结合的方法可以在不需要人工交互的情况下准确地自动检测出太阳活动区.
基金supported by the National Key Research and Development Program of China(2018YFA0404603)the Joint Research Fund in Astronomy(Nos.U1831204,U1931141 and U1631129)under cooperative agreement between the National Natural Science Foundation of China(NSFC)and the Chinese Academy of Sciences(CAS)+3 种基金the NSFC(11903009)the Yunnan Key Research and Development Program(2018IA054)the open research program of the CAS Key Laboratory of Solar Activity(KLSA201807)the major scientific research project of Guangdong regular institutions of higher learning(2017KZDXM062)
文摘Studies on the periodic variation and the phase relationship between different solar activity indicators are useful for understanding the long-term evolution of solar activity cycles.Here we report the statistical analysis of grouped solar flare(GSF) and sunspot number(SN) during the time interval from January 1965 to March 2009.We find that,(1) the significant periodicities of both GSF and SN are related to the differential rotation periodicity,the quasi-biennial oscillation(QBO),and the eleven-year Schwabe cycle(ESC),but the specific values are not absolutely identical;(2) the ESC signal of GSF lags behind that of SN with an average of 7.8 months during the considered time interval,which implies that the systematic phase delays between GSF and SN originate from the inter-solar-cycle signal.Our results may provide evidence about the storage of magnetic energy in the corona.
文摘We propose a magnetic confinement nuclear fusion mechanism for the evolution of a solar flare in the solar atmosphere.The mechanism agrees with two observed characteristics of explosive flares and coronal mass ejections(CMEs) that have proved to be very difficult to explain with previous mechanisms:the huge enrichments of3 He and the high energy gamma ray radiation.The twisted magnetic flux rope is a typical structure during the solar flares,which is closely related to the solar active region that magnetic fields have almost complete control over the plasma.Consequently,the plasma inside the flux rope is heated to more than 1.0×107 K by an adiabatic compression process,and then the thermonuclear fusion can take place in the flux rope accompanied with high energy gamma rays.We utilize the time-dependent ideal 2.5-dimensional magnetohydrodynamic(MHD) simulation to demonstrate the physical mechanism for producing flares,which reveals three stages of flare development with the process of magnetic energy conversion and intense release during the solar flares and CMEs in the solar atmosphere.Furthermore,we discuss the relationship between magnetic reconnection and solar eruptions.
文摘作为中国首颗综合性太阳探测卫星的先进天基太阳天文台(Advanced Space-based Solar Observatory,ASO-S)于北京时间2022年10月9日7时43分在酒泉卫星发射中心成功发射.扼要介绍ASO-S卫星提出的背景、卫星的研制历程、科学目标、载荷构成、任务总体以及卫星研制的组织架构,并对卫星的运行和科学产出略作展望.
