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A Special Kind of interplanetary Coronal Mass Ejection

Research in Astronomy and Astrophysics 2024年第12期24卷 185-193页

作者： H.Q.Feng Y.Zhao G.Q.Zhao H.B.Li L.Xiang J.M.Wang Institute of Space Physics Luoyang Normal University Henan Key Laboratory of Electromagnetic Transformation and Detection Luoyang Normal University

It is generally believed that coronal mass ejections(CMEs) have magnetic flux rope structures because of their helical shapes. However, only about 30%–40% of interplanetary CMEs(ICMEs) have a local magnetic flux rope structure. The usual explanations are that the spacecraft only crossed the flank of the ropes and failed to detect the complete magnetic flux rope structure or that some processes destroyed these magnetic flux rope structures. Several studies suggest that some ICMEs inherently possess disordered magnetic fields and consequently exhibit no magnetic flux-rope structures. We introduce a special kind of ICME which has a low magnetic field magnitude and stable magnetic field direction, relatively fast expansion speed, and lower proton temperature and density. All three of the measured magnetic field components are relatively stable. We want to know whether these ICMEs also have magnetic flux rope structures or not. We identified 20 special ICMEs and analyzed their evolution based on their observed characteristics. We took a special ICME as an example, which had an apparent rope configuration at 1 au but evolved to a special ICME at 5.4 au, to illustrate that this kind of ICME could come from magnetic clouds(MCs) whose rope structure had been being stretched due to expansion. We inferred that the missing obvious flux rope structure may be due to the expansion of MCs, not the flank crossing effect. However, more than 50% of the events were associated with the dominant x-component of the magnetic field, which indicates a leg ***, the detection of part of these special ICMEs may also be the result of the leg-crossing effect.

关键词： (Sun:) solar wind interplanetary medium Sun: coronal mass ejections (CMEs)

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NUMERICAL STUDY OF THE LONGITUDINALLY ASYMMETRIC DISTRIBUTION OF SOLAR ENERGETIC PARTICLES IN THE HELIOSPHERE

NUMERICAL STUDY OF THE LONGITUDINALLY ASYMMETRIC DISTRIBUTIO...

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中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： H.-Q.He W.Wan Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences CAS Key Laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity of Science and Technology of China

Solar energetic particles(SEPs) affect the solar–terrestrial space environment and are very important to space weather *** this work,we numerically investigate the transport processes of SEPs in the three-dimensional interplanetary magnetic field,with an emphasis on the longitudinal distribution of SEPs in the *** confirm our previous finding that there exists an east–west longitudinal asymmetry in the SEP intensities,i.e.,with the same longitude separations between the solar source centers and the magnetic footpoint of the observer,the fluxes of SEP events originating from solar sources located on the eastern side of the nominal magnetic footpoint of the observer are systematically larger than those of the SEP events originating from sources located on the western *** discuss the formation mechanism of this phenomenon,and conclude that the longitudinally asymmetric distribution of SEPs results from the east–west azimuthal asymmetry in the topology of the heliospheric magnetic field as well as the effects of perpendicular diffusion on the transport of SEPs in the *** results will be valuable to understanding Sun–Earth relations and useful for space weather forecasting.

关键词： interplanetary medium magnetic fields solar–terrestrial relations Sun:flares Sun:particle emission

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The dependence of the parallel and perpendicular mean free paths on the rigidity of the solar energetic particles:Theoretical model versus observations

The dependence of the parallel and perpendicular mean free p...

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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： H.-Q.He W.Wan Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of Sciences

*** dependence of the parallel and perpendicular mean free paths on the particle rigidity is an important topic in the studies of the diffusion and propagation of charged energetic particles in a large-scale turbulent magnetic field. *** this work,we investigate the dependence of the parallel and perpendicular mean free paths on the rigidity of solar energetic particles(SEPs) by means of both the theoretical model and spacecraft observations with regard to several typical SEP events. Methods.A direct method developed by previous studies and derived from the focused transport equation and Taylor-Green-Kubo (TGK) formulation is applied to explicitly determine the parallel and perpendicular mean free paths of SEPs in a turbulent and spatially varying magnetic field. *** find that the parallel and perpendicular mean free paths,λ andλ,of energetic protons monotonically decrease with increasing particle rigidity,and the ratioλ/λmonotonically increases with particle rigidity,when the magnetic turbulence is weak. Taking a series of typical SEP events together,it can also be seen that the ratioλ⊥/λof the perpendicular to the parallel mean free paths remains in the range of 0.001-0.2.

关键词： interplanetary medium magnetic fields solar terrestrial relations Sun coronal mass ejections flares Sun:particle emission

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