The Structure of Solar Coronal Mass Ejections in the Extreme-ultraviolet Passbands

Song, Hongqiang; Zhang, J.; Li, L. P.; Liu, Y. D.; Zhu, Bowen; Wang, B.; Zheng, Ruisheng; Chen, Yanlai

doi:10.3847/1538-4357/ab50b6

Cited by 21 publications

(29 citation statements)

References 49 publications

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“…A similar result was also reported by Bein et al (2011) but it must be noted that their numbers suffered from projection effects and their numbers were obtained by combining Extreme Ultraviolet (EUV) and White Light (WL) observations which brings in an additional ambiguity of whether the same physical feature is being tracked in EUV and WL (for a discussion, see Song et al 2019, and references therein), as the former corresponds to the temperature structure of a CME while the later corresponds to the density structure (Ying et al 2020). In our work, we do away with both of these limitations, as our measured numbers are in 3D and the measurements are done uniquely in WL.…”

Section: Resultssupporting

confidence: 73%

An Insight into the Coupling of CME Kinematics in Inner and Outer Corona and the Imprint of Source Regions

Majumdar,

Patel,

Pant

et al. 2021

Preprint

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Despite studying Coronal Mass Ejections (CMEs) for several years, we are yet to have a complete understanding of their kinematics. In this regard, the change in kinematics of the CMEs, as they travel from the inner corona (< 3R ) to the higher heights is essential. We do a follow up statistical study of several 3D kinematic parameters of 59 CMEs studied by Majumdar et al. (2020). The source regions of these CMEs are identified and classified as Active Regions (ARs), Active Prominences (APs), and Prominence Eruptions (PEs). We study several statistical correlations between different kinematic parameters of the CMEs. We show that the average kinematic parameters change as they propagate from the inner to the outer corona, indicating the importance of the region where normally the common practice is to perform averaging. We also find that the parameters in the outer corona is highly influenced by those in the inner corona, thus indicating the importance of inner corona in the understanding of the kinematics. We further find that the source regions of the CMEs tend to have a distinct imprint on the statistical correlations between different kinematic parameters, and that an overall correlation tends to wash away this crucial information. The results of this work lends support towards possibly different dynamical classes for the CMEs from active regions and prominences which is manifested in their kinematics.

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Section: Resultssupporting

confidence: 73%

An Insight into the Coupling of CME Kinematics in Inner and Outer Corona and the Imprint of Source Regions

Majumdar,

Patel,

Pant

et al. 2021

Preprint

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“…Since the core has been identified as the flux rope in white-light images of CMEs (e.g. Howard et al 2017;Song et al 2019), we use its heliocentric distance, about 3 R , to estimate the height of the flux rope. From the location of the two radio sources at high frequencies (432 MHz) we infer that the two legs of the flux rope were distant by about 14 • .…”

Section: F3 Correlated Evolution Of Brightness Temperatures In the mentioning

confidence: 99%

“…A coronal mass ejection (CME) is generally understood to comprise a magnetic flux rope, which at some time starts to rise into the high corona (e.g. Démoulin & Aulanier 2010;Howard et al 2017;Song et al 2019). It leaves behind a stressed magnetic field that will re-arrange itself over several hours.…”

Section: Introductionmentioning

confidence: 99%

Polarisation and source structure of solar stationary type IV radio bursts

Salas-Matamoros

Klein

2020

A&A

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The reconfiguration of the magnetic field during and after a coronal mass ejection (CME) may be accompanied by radio emission from non-thermal electrons. In particular, stationary type IV bursts (also called storm continua) are emitted by electrons in closed magnetic configurations usually located in the wake of the outward-travelling CME. Although stationary type IV bursts, which stand out by their long duration (up to several hours) and strong circular polarisation, have been known for more than fifty years, there have been no systematic studies since the 1980s. In this work we use the data pool of the Nançay Radioheliograph together with white-light coronagraphy, EUV imaging and magnetography from the SoHO, Proba2, SDO and STEREO spacecraft to revisit the source structure and polarisation of a sample of seven well-defined stationary type IV bursts at decimetre-to-metre wavelengths. The radio sources are most often found in one leg, in one case both legs, of the magnetic flux rope erupting into the high corona during the CME. The cross-correlation of the brightness temperature time profiles in the event with sources in both legs implies that the radiating electrons have energies of a few tens of keV. Comparison with the magnetic field measured in the photosphere and its potential extrapolation into the corona shows that the radio emission is in the ordinary mode. This result was inferred historically by means of the hypothesis that the magnetic field orientation in the radio source was that of the dominant sunspot in the parent active region. This hypothesis is shown here to be in conflict with noise storms in the same active region. It is confirmed that the polarisation of stationary type IV continua may be strong, but is rarely total, and that it gradually increases in the early phase of the radio event. We find that the increase is related to the gradual disappearance of some weakly polarised or unpolarised substructure, which dominates the first minutes of the radio emission.

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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 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. Researchers also suggest that the dark cavity corresponds to a low-density region with a sheared magnetic field in the early eruption stage [16].…”

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 Structure of Solar Coronal Mass Ejections in the Extreme-ultraviolet Passbands

Cited by 21 publications

References 49 publications

An Insight into the Coupling of CME Kinematics in Inner and Outer Corona and the Imprint of Source Regions

An Insight into the Coupling of CME Kinematics in Inner and Outer Corona and the Imprint of Source Regions

Polarisation and source structure of solar stationary type IV radio bursts

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

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