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Magnetohydrostatic modeling of the solar atmosphere

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Science China(Technological Sciences) 2022年第8期65卷 1710-1726页

作者： ZHU XiaoShuai NEUKIRCH Thomas WIEGELMANN Thomas State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Mathematics and Statistics University of St AndrewsSt Andrews KY169SSUK Max-Planck-Institut f¨ur Sonnensystemforschung G¨ottingen 37077Germany

Understanding structures and evolutions of the magnetic fields and plasma in multiple layers on the Sun is very important. A force-free magnetic field which is an accurate approximation of the solar corona due to the low plasma β has been widely studied and used to model the coronal magnetic structure. While the force-freeness assumption is well satisfied in the solar corona, the lower atmosphere is not force-free given the high plasma β. Therefore, a magnetohydrostatic(MHS) equilibrium which takes into account plasma forces, such as pressure gradient and gravitational force, is considered to be more appropriate to describe the lower atmosphere. This paper reviews both analytical and numerical extrapolation methods based on the MHS assumption for calculating the magnetic fields and plasma in the solar atmosphere from measured magnetograms.

关键词： magnetic field photosphere chromosphere corona

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

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

Data-driven Simulations of Magnetic Field Evolution in Active Region 11429:Magneto-frictional Method Using PENCIL CODE

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Research in Astronomy and Astrophysics 2024年第2期24卷 74-82页

作者： P.Vemareddy Jorn Warnecke Ph.A.Bourdin Indian Institute of Astrophysics Sarjapur roadII BlockKoramangalaBengaluru-560034India Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3D-37077 GöttingenGermany Institute of Physics University of GrazUniversitätsplatz 5A-8010 GrazAustria

Coronal magnetic fields evolve quasi-statically over long timescales and dynamically over short *** of now there exist no regular measurements of coronal magnetic fields,and therefore generating the coronal magnetic field evolution using observations of the magnetic field at the photosphere is a fundamental requirement to understanding the origin of transient phenomena from solar active regions(ARs).Using the magneto-friction(MF)approach,we aim to simulate the coronal field evolution in the solar AR *** MF method is implemented in the open source PENCIL CODE along with a driver module to drive the initial field with different boundary conditions prescribed from observed vector magnetic fields at the *** order to work with vector potential and the observations,we prescribe three types of bottom boundary drivers with varying free-magnetic *** MF simulation reproduces the magnetic structure,which better matches the sigmoidal morphology exhibited by Atmospheric Imaging Assembly(AIA)images at the pre-eruptive *** found that the already sheared field further driven by the sheared magnetic field will maintain and further build the highly sheared coronal magnetic configuration,as seen in AR ***-driven MF simulation is a viable tool to generate the coronal magnetic field evolution,capturing the formation of the twisted flux rope and its eruption.

关键词： Sun corona-Sun evolution-Sun magnetic fields-Sun photosphere

The Nature of the Elongated Granulations and Stretched Dark Lanes in a Newly Emerging Flux Region

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Research in Astronomy and Astrophysics 2024年第11期24卷 76-84页

作者： Jincheng Wang Xiaoli Yan Yunnan Observatories Chinese Academy of SciencesKunming 650011China Yunnan Key Laboratory of Solar Physics and Space Science Kunming 650011China

In this study,we explore the elongated granulations and stretched dark lanes within the emerging anti-Hale active region NOAA AR *** high-resolution observations from the New Vacuum Solar Telescope,we discern a prevalence of elongated granules and stretched dark lanes associated with the emergence of new magnetic flux positioned between two primary opposing magnetic *** elongated granulations and stretched dark lanes exhibit an alignment of strong transverse fields and a significant inclination *** endpoints of these features separate from each other,with their midpoints predominantly characterized by blueshifted signals in the *** suggests a close association between elongated granules and stretched dark lanes with the newly emerging ***,we find that the stretched dark lanes display a more pronounced correlation with strong blueshifts and photospheric transverse magnetic fields compared to the elongated *** transverse magnetic field within these stretched dark lanes reaches magnitudes of approximately 300-400 G,and the inclination angle demonstrates an“arch-like”pattern along the trajectory of the stretched dark *** on these observed characteristics,we infer the presence of an emerging flux tube with an“arch-like”shape situated along the stretched dark ***,we conclude that the stretched dark lanes likely represent manifestations of the emerging flux tube,while the elongated granulations may correspond to the gaps between the emerging flux tubes.

关键词： Sun granulation Sun magnetic fields Sun photosphere

Long-term Variation of the Solar Polar Magnetic Fields at Different Latitudes

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Research in Astronomy and Astrophysics 2024年第7期24卷 190-197页

作者： Shuhong Yang Jie Jiang Zifan Wang Yijun Hou Chunlan Jin Qiao Song Yukun Luo Ting Li Jun Zhang Yuzong Zhang Guiping Zhou Yuanyong Deng Jingxiu Wang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Solar Activity and Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China School of Space and Environment Beihang UniversityBeijing 102206China Key Laboratory of Space Weather National Satellite Meteorological Center(National Center for Space Weather)China Meteorological AdministrationBeijing 100081China Innovation Center for FengYun Meteorological Satellite(FYSIC) Beijing 100081China School of Physics and Materials Science Anhui UniversityHefei 230601China

The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar ***,because our view of the Sun is limited in the ecliptic plane,the polar regions remain largely *** the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021,we investigate the long-term variation of the magnetic fields in polar caps at different *** Hinode magnetic measurements show that the polarity reversal processes in the north and south polar caps are *** variation of the averaged radial magnetic flux density reveals that,in each polar cap,the polarity reversal is completed successively from the 70°latitude to the pole,reflecting a poleward magnetic flux migration *** results clarify the polar magnetic polarity reversal process at different latitudes.

关键词： dynamo-Sun magnetic fields-Sun photosphere

Observational cross helicity on the solar surface

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 589-596页

作者： ZHAO MingYu WANG XiaoFan ZHANG HongQi Key Laboratory of Solar Activity National Astronomical ObservatoryChinese Academy of Sciences

We analyzed the correlation of the solar magnetograms and Dopplergrams from SOHO/MDI and SDO/HMI respectively. It is found that the full disk correlation coefficient of Dopplergrams is more than 0.80 between SOHO/MDI and SDO/HMI. The full disk correlation coefficient of magnetograms is about 0.73 and is more than 0.95 for active regions only. We also analyzed the distribution of the cross helicity （velocity-magnetic-field correlation） on the solar surface. It is found that the latitude distributions of the cross helicity based on SOHO/MDI data and SDO/HMI data have similar tendencies, and in the analysis of solar active regions the amplitude of the horizontal component of the mean cross helicity is about two times the line-of-sight one.

关键词： cross helicity photosphere magnetic fields solar activity

A new approach to solar flare prediction

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Frontiers of physics 2020年第3期15卷 123-149,F0004页

作者： Michael L.Goodman Chiman Kwan Bulent Ayhan Eric L.Shang Jacobs Space Exploration Group Natural Environments Branch-EV44NASA Marshall Space Flight CenterHuntsvilleAL35812USA Applied Research LLC 9605 Medical Center Drive-Suite 127 ERockvilleMD20850USA

All three components of the current density are required to compute the heating rate due to free magnetic energy *** we present a first test of a new model developed to determine if the times of increases in the resistive heating rate in active region(AR)photospheres are correlated with the subsequent occurrence of M and X flares in the corona.A data driven,3D,non-force-free magnetohydrodynamic model restricted to the near-photospheric region is used to compute time series of the complete current density and the resistive heating rate per unit volume[Q(t)]in each pixel in neutral line regions(NLRs)of 14 *** model is driven by time series of the magnetic field B measured by the Helioseismic&Magnetic Imager on the Solar Dynamics Observatory(SDO)*** Doppler periods due to SDO orbital motion are filtered out of the time series for B in every AR *** each AR,the cumulative distribution function(CDF)of the values of the NLR area integral Qi(t)of Q(t)is found to be a scale invariant power law distribution essentially identical to the observed CDF for the total energy released in coronal *** suggests that coronal flares and the photospheric Qi are correlated,and powered by the same *** model predicts spikes in Qi with values orders of magnitude above background *** spikes are driven by spikes in the non-force free component of the current *** times of these spikes are plausibly correlated with times of subsequent M or X flares a few hours to a few days *** spikes occur on granulation scales,and may be signatures of heating in horizontal current *** is also found that the times of relatively large values of the rate of change of the NLR unsigned magnetic flux are also plausibly correlated with the times of subsequent M and X flares,and spikes in Qi.

关键词： active regions magnetic fields flares forecasting heating photosphere models magnetohydrodynamics

Solar surface magnetoconvection simulations: A brief review of solar dermatology

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Science China(Physics,Mechanics & Astronomy) 2009年第11期52卷 1665-1669页

作者： CAMERON Robert Max-Planck-Institute fr Sonnensystemforschung Katlenburg-Lindau

Rapid improvement in the speed of computers has enabled realistic simulations of magnetoconvective processes in the surface layers of the Sun. The simulations now cover a wide range of features found in observations. In many cases a direct comparison with the observations is justified, and in all cases our understanding and interpretation of the observations is being improved. Current and future opportunities and difficulties will be discussed.

关键词： Sun photosphere magnetohydrodynamics