The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection

Song, Hongqiang; Cheng, X.; Chen, Yanlai; Zhang, J.; Wang, B.; Li, L. P.; Li, B.; Hu, Qiang; Li, G.

doi:10.3847/1538-4357/aa8d1a

Cited by 21 publications

(31 citation statements)

References 67 publications

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“…The elemental compositions within ICMEs are determined by many factors, such as the properties of source regions and the detailed eruption processes (Song and Yao, 2020). In the meantime, many CMEs possess the three-part structure (Vourlidas et al, 2013;Song et al, 2017bSong et al, , 2019a that result from filament or hot channel eruptions. The different parts of CMEs could contain different FIP biases and thermodynamic evolution from the Sun.…”

Section: The Large Standard Deviationmentioning

confidence: 99%

Solar Cycle Dependence of ICME Composition

Song

Sun

et al. 2021

Sol Phys

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Coronal mass ejections (CMEs) belong to the most energetic explosions in the solar atmosphere, and their occurrence rates exhibit obvious solar cycle dependence with more events taking place around solar maximum. Composition of interplanetary CMEs (ICMEs), referring to the charge states and elemental abundances of ions, opens an important avenue to investigate CMEs. In this paper, we conduct a statistical study on the charge states of five elements (Mg, Fe, Si, C, and O) and the relative abundances of six elements (Mg/O, Fe/O, Si/O, C/O, Ne/O, and He/O) within ICMEs from 1998 to 2011, and find that all the ICME compositions possess a solar cycle dependence. All of the ionic charge states and most of the relative elemental abundances are positively correlated with sunspot numbers (SSNs), and only the C/O ratios are inversely correlated with the SSNs. The compositions (except the C/O) increase with the SSNs during the ascending phase (1998–2000 and 2009–2011) and remain elevated during solar maximum and descending phase (2000–2005) compared to solar minimum (2007–2009). The charge states of low-FIP (first ionization potential) elements (Mg, Fe, and Si) and their relative abundances are correlated well, while no clear correlation is observed between the C6+/C5+ or C6+/C4+ and C/O. Most interestingly, we find that the Ne/O ratios of ICMEs and slow solar wind have the opposite solar cycle dependence.

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Section: The Large Standard Deviationmentioning

confidence: 99%

Solar Cycle Dependence of ICME Composition

Song

Sun

et al. 2021

Sol Phys

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“…The CME cores used to be interpreted as eruptive filaments (Gilbert et al 2000). However, Song et al (2017) performed a statistical work based on looking into 42 CMEs with three-part structures and illustrated that 70% of the events are not associated with filaments. Theories for the CME front/leading edges are fairly involved and reviewed in Chen (2011) andWarmuth (2015).…”

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confidence: 99%

The Triple-layered Leading Edge of Solar Coronal Mass Ejections

Keppens

Cai

et al. 2020

ApJL

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In a high-resolution, 3D resistive magnetohydrodynamic (MHD) simulation of an eruptive magnetic flux rope (MFR), we revisit the detailed 3D magnetic structure of a coronal mass ejection (CME). Our results highlight that there exists a helical current sheet (HCS) that wraps around the CME bubble. This HCS results from the interaction between the CME bubble and the ambient magnetic field, where it represents a tangential discontinuity in the magnetic topology. Its helical shape is ultimately caused by the kinking of the MFR that resides within the CME bubble. In synthetic SDO/AIA images, processed to logarithmic scale to enhance otherwise unobservable features, we show a clear triple-layered leading edge: a bright fast shock front, followed by a bright HCS, and within it a bright MFR. These are arranged in sequence and expand outward continuously. We suggest that the HCS is a possible explanation for the bright leading edges seen near CME bubbles and also for the non-wave component of global EUV disturbances.

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“…The cavity and core have been considered as the MFR cross section and erupted filament, respectively, for several decades. However, recent studies clearly demonstrated that both the filaments and hot channel MFRs can appear as the bright core [13][14][15][16]. The hot channels are first revealed through extreme ultraviolet passbands sensitive to high temperatures (e.g., 131 and 94 Å) [17], and they can also be observed in hard X-ray [18] and microwave [19] images.…”

Section: Introductionmentioning

confidence: 99%

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

Song

Cheng

et al. 2021

Front. Phys.

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Coronal mass ejections (CMEs) are one of the most energetic explosions in the solar system. It is generally accepted that CMEs result from eruptions of magnetic flux ropes, which are dubbed as magnetic clouds (MCs) in interplanetary space. The composition (including the ionic charge states and elemental abundances) is determined prior to and/or during CME eruptions in the solar atmosphere and does not alter during MC propagation to 1 AU and beyond. It has been known that the composition is not uniform within a cross section perpendicular to the MC axis, and the distribution of ionic charge states within a cross section provides us an important clue to investigate the formation and eruption processes of flux ropes due to the freeze-in effect. The flux rope is a three-dimensional magnetic structure intrinsically, and it remains unclear whether the composition is uniform along the flux rope axis as most MCs are only detected by one spacecraft. In this study, we report an MC that was observed by Advanced Composition Explorer at ∼1 AU during March 4–6, 1998, and Ulysses at ∼5.4 AU during March 24–28, 1998, sequentially. At these times, both spacecraft were located around the ecliptic plane, and the latitudinal and longitudinal separations between them were ∼2.2° and ∼5.5°, respectively. It provides us an excellent opportunity to explore the axial inhomogeneity of flux rope composition, as both spacecraft almost intersected the cloud center at different sites along its axis. Our study shows that the average values of ionic charge states exhibit significant difference along the axis for carbon, and the differences are relatively slight but still obvious for charge states of oxygen and iron as well as the elemental abundances of iron and helium. Besides the means, the composition profiles within the cloud measured by both spacecraft also exhibit some discrepancies. We conclude that the inhomogeneity of composition exists along the cloud axis.

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The Three-part Structure of a Filament-unrelated Solar Coronal Mass Ejection

Cited by 21 publications

References 67 publications

Solar Cycle Dependence of ICME Composition

Solar Cycle Dependence of ICME Composition

The Triple-layered Leading Edge of Solar Coronal Mass Ejections

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

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