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On the Relation Between Coronal Green Line Brightness and Magnetic Fields Intensity

Research in Astronomy and Astrophysics 2022年第7期22卷 128-138页

作者： Xue-Fei Zhang Yu Liu Ming-Yu Zhao Teng-Fei Song Jing-Xing Wang Xiao-Bo Li Zi-Han Li Yunnan Observatories Chinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China Yunnan Normal University School of Physics and Electronic InformationKunming 650000China

Two-dimensional(2 D) solar coronal magnetogram is difficult to be measured directly until *** the previous knowledge,a general relation has been noticed that the brighter green-line brightness for corona,the higher coronal magnetic field intensity may correspond *** try to further reveal the relationship between coronal green line brightness and magnetic field intensity,we use the 2 D coronal images observed by Yunnan Observatories Greenline Imaging System(YOGIS) of the 10 cm Lijiang coronagraph and the coronal magnetic field maps calculated from the current-free extrapolations with the photospheric magnetograms taken by Helioseismic and Magnetic Imager(HMI) on board the Solar Dynamics Observatory(SDO) *** our analysis,we identified the coronal loop structures and construct two-dimensional maps of the corresponding magnetic field intensity in the plane of the sky(POS) above the *** derive the correlation coefficients between the coronal brightness and the magnetic field intensity for different heights of coronal *** further use a linear combination of a Gaussian and a quadratic profile to fit the correlation coefficients distribution,finding a largest correlation coefficient of 0.82 near 1.1 R(solar radii) where is almost the top of the closed loop *** the small closed loop system identified,the correlation coefficient distributions crossing and covering the loop are *** also investigate the correlation with extended heliocentric latitude zones and long period of one whole Carrington Rotation,finding again that the maximum correlation coefficient occurs at the same *** is the first time for us to find that the correlation coefficients are high(all are larger than 0.8) at the loop-tops and showing poor correlation coefficients with some fluctuations near the feet of the coronal *** findings indicate that,for the heating of the low-latitude closed loops,both DC(dissipation of currents) and AC(dissipation of Alfvé

关键词： sun:magnetic fields sun:corona Stars:coronae sun:activity sun:atmosphere sun:coronal mass ejections(CMEs) sun:fundamental parameters sun:heliosphere sun:UV radiation

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Alpha/proton Instability in the Presence of Proton and Alpha Temperature Anisotropy and its Application to the Deceleration of Alpha Particles in the Solar Wind

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Research in Astronomy and Astrophysics 2022年第1期22卷 192-204页

作者： Wen-Lu Zhang Liang Xiang Qiu-Huan Li Si-Yi Lang Hong-Wei Yu Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications School of Physics and ElectronicsHunan Normal UniversityChangsha 410081China Institute of Space Physics Luoyang Normal UniversityLuoyang 471934China

Observations of solar wind plasma find that the drift velocity between alpha beams and protons,vα,is reduced with the heliocentric distance,but the ratio of vαto vA(the local Alfven velocity)does not vary obviously and has a typical velocity ratio of vα/vA≤*** alpha beam instability is believed to be responsible for the deceleration of alpha beams in the solar ***,the role of the temperature anisotropy of ions(protons and alpha particles)on the alpha beam instability has not been *** on the kinetic theory of the PDRK solver,this study systemically investigates the alpha beam instability in the presence of proton and alpha temperature anisotropies and considers the effects of these temperature anisotropies on the instability at an arbitrary propagation angle relative to the ambient magnetic *** is found that the real frequencies,growth rates and threshold conditions of the excited waves sensitively depend on the proton temperature anisotropy T_(i⊥)/T_(i‖)and the alpha temperature anisotropy T_(α⊥)/T_(α‖),as well as the parallel electron betaβe‖.In particular,for both alpha beam and proton temperature anisotropy driven cases,the parallel magnetosonic/whistler(PM/W),backward magnetosonic/whistler(BM/W)and oblique Alfvén/ion cyclotron(OA/IC)waves arise when T_(i⊥)/T_(i‖)*** presence of anisotropic protons leads to a lower velocity threshold for the OA/IC and BM/W waves at T_(i⊥)/T_(i‖)*** both alpha beam and alpha temperature anisotropy driven cases,the PM/W and OA/IC waves are unstable when T_(α⊥)/T_(α‖)*** presence of anisotropic alpha particles results in a lower threshold velocity for the PM/W wave at T_(α⊥)/T_(α‖)<1 and for the PA/IC,OM/W and mirror waves at T_

关键词： (sun:)solar wind sun:heliosphere waves

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