The Distributions of Iron Average Charge States in Small Flux Ropes in Interplanetary Space: Clues to Their Twisted Structures

Huang, Jia; Liu, Yong C.‐M.; Peng, Jinfang; Zheng, Qi; Li, Hui; Klecker, B.; Song, Hongqiang; Zheng, Jinlei; Hu, Qiang

doi:10.1029/2018ja025660

Cited by 20 publications

(18 citation statements)

References 70 publications

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“…Feng and Wang found that SIMFRs exhibit the same high-charge-state signatures as MCs, and hot materials within SIMFRs must be heated by related flares in the corona[43]. These findings provide reliable evidence for the conjecture that SIMFRs and MCs havethe same coronal origins and thatSIMFRs are interplanetary counterparts of small CMEs[43].Huang et al[51]…”

mentioning

confidence: 85%

Small interplanetary magnetic flux rope

Feng

Zhao

Wang

2019

Sci. China Technol. Sci.

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Small interplanetary magnetic flux ropes (SIMFRs) are often detected by space satellites in the interplanetary space near 1 AU. These ropes can be fitted by a cylindrically symmetric magnetic model. The durations of SIMFRsare usually <12 h, and the diameters of SIMFRsare <0.20 AU and show power law distribution. Most SIMFRs are observed in the typically slow solar wind (<500 km/s), and only several events are observed with high speed (>700 km/s). Some SIMFRs demonstrate abnormal heavy ion compositions, such as abnormally high He abundance, abnormally high average iron ionization, and enhanced O

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confidence: 85%

Small interplanetary magnetic flux rope

Feng

Zhao

Wang

2019

Sci. China Technol. Sci.

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“…The end result is that the ionization fractions do not vary any longer, i.e., freeze-in. This means that the ionic fractions measured in situ are largely determined by the physical parameters near the Sun where freeze-in occurs (Rakowski, Laming, and Lepri, 2007;Lynch et al, 2011;Gruesbeck et al, 2011;Gruesbeck, Lepri, and Zurbuchen, 2012;Song et al, 2015b,c), which have been further used to infer the eruption process of flux ropes (Song et al, 2016;Wang et al, 2017;Huang et al, 2018). It should be noted that the different structures of CMEs have different freeze-in history (Gruesbeck, Lepri, and Zurbuchen, 2012;, which leads to the complex nature of ICMEs and makes the interpretation of ions in situ less straightforward.…”

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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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“…The charge states within ICMEs are frozen-in near the Sun [33], and the relative abundances of elements with different first ionization potentials (FIPs) are different obviously in the corona and photosphere [34,35]. As the composition does not alter during CME propagation to 1 AU and beyond [36], the in situ data are also employed to analyze the MFR formation [28,37,38] and plasma origin [39,40] of CMEs. So far, the most complete composition data of ICMEs are provided by the solar wind ion composition spectrometer (SWICS) aboard Advanced Composition Explorer (ACE) and Ulysses, which can provide the charge states and elemental abundances of ∼10 elements [41].…”

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 Distributions of Iron Average Charge States in Small Flux Ropes in Interplanetary Space: Clues to Their Twisted Structures

Cited by 20 publications

References 70 publications

Small interplanetary magnetic flux rope

Small interplanetary magnetic flux rope

Solar Cycle Dependence of ICME Composition

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

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