On the Role of Repetitive Magnetic Reconnections in Evolution of Magnetic Flux Ropes in Solar Corona

Kumar, Sanjay; Bhattacharyya, R.; Joshi, Bhuwan; Smolarkiewicz, Piotr K.

doi:10.3847/0004-637x/830/2/80

Cited by 31 publications

(27 citation statements)

References 47 publications

(67 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to define the size, orientation, and location of the selected boxes we examined the post-flare loops in AIA 94Å images. As the post-flare arcades are believed to be the regions above which magnetic reconnection occurs (Liu et al, 2013;Joshi, Magara, and Inoue, 2014;Kumar et al, 2016b), we have selected our region of interest by enclosing the major post flare arcade structures seen in AIA 94Å images ( of these two values are greater than the noise level of ten Gauss on either of the two arrays, then the pixel that is in between these two minimum and maximum valued pixels is identified as the pixel tracing the PIL. These pixels were then joined to make the PIL.…”

Section: Discussionmentioning

confidence: 99%

A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

Sarkar

Srivastava

2018

Sol Phys

View full text Add to dashboard Cite

We investigate the morphological and magnetic characteristics of solar active region (AR) NOAA 12192. AR 12192 was the largest region of Solar Cycle 24; it underwent noticeable growth and produced 6 X-class flares, 22 M-class flares, and 53 C-class flares in the course of its disc passage. However, the most peculiar fact of this AR is that it was associated with only one CME in spite of producing several X-class flares. In this work, we carry out a comparative study between the eruptive and non-eruptive flares produced by AR 12192. We find that the magnitude of abrupt and permanent changes in the horizontal magnetic field and Lorentz force are significantly smaller in the case of the confined flares compared to the eruptive one. We present the areal evolution of AR 12192 during its disc passage. We find the flare-related morphological changes to be weaker during the confined flares, whereas the eruptive flare exhibits a rapid and permanent disappearance of penumbral area away from the magnetic neutral line after the flare. Furthermore, from the extrapolated nonlinear force-free magnetic field, we examine the overlying coronal magnetic environment over the eruptive and non-eruptive zones of the AR. We find that the critical decay index for the onset of torus instability was achieved at a lower height over the eruptive flaring region, than for the non-eruptive core area. These results suggest that the decay rate of the gradient of overlying magnetic field strength may play a decisive role to determine the CME productivity of the AR. In addition, the magnitude of changes in the flare-related magnetic characteristics are found to be well correlated with the nature of solar eruptions.

show abstract

Section: Discussionmentioning

confidence: 99%

A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

Sarkar

Srivastava

2018

Sol Phys

View full text Add to dashboard Cite

show abstract

“…Both theoretical and observational studies reveal that MFRs can form prior to [17,[20][21][22][23] and during [24][25][26][27][28] solar eruptions, while they might exist before eruptions in more events [29]. The numerical simulations demonstrate that the repetitive magnetic reconnections could play an important role during the MFR evolution [30]. The remote-sensing observations have been widely used to investigate the MFR formation process [26,31,32].…”

Section: Introductionmentioning

confidence: 99%

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

Song

Cheng

et al. 2021

Front. Phys.

View full text Add to dashboard Cite

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.

show abstract

“…Observationally, a flux rope can be identified in different forms: filament (Zirin 1988;Martin 1998), prominence (Tandberg-Hanssen 1995;Parenti 2014), coronal cavity (Forland et al 2013;Gibson 2015), hot channel (Zhang et al 2012;Cheng et al 2013;Mitra & Joshi 2019;Sahu et al 2020), coronal sigmoid (Rust & Kumar 1996;Manoharan et al 1996;Joshi et al 2017a;Mitra et al 2018) etc. The processes involved in the triggering of a flux rope from its stable condition and its successive evolution within the source region are rather complex and debatable (see e.g., Chatterjee & Fan 2013; Kumar et al 2016;Prasad et al 2020). Different mechanisms have been proposed in this regard, which can be classified in two general groups: ideal instability and resistive instability.…”

Section: Introductionmentioning

confidence: 99%

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube

Mitra,

Joshi

2021

Preprint

Self Cite

View full text Add to dashboard Cite

We present a comprehensive analysis of the formation and evolution of a fan-spine-like configuration that developed over a complex photospheric configuration where dispersed negative polarity regions were surrounded by positive polarity regions. This unique photospheric configuration, analogous to the geological "atoll" shape, hosted four homologous flares within its boundary. Computation of the degree of squashing factor (Q) maps clearly revealed an elongated region of high Q-values between the inner and outer spine-like lines, implying the presence of an hyperbolic flux tube (HFT). The coronal region associated with the photospheric atoll configuration was distinctly identified in the form of a diffused dome-shaped bright structure directly observed in EUV images. A filament channel resided near the boundary of the atoll region. The activation and eruption of flux ropes from the filament channel led to the onset of four eruptive homologous quasi-circular ribbon flares within an interval of ≈11 hours. During the interval of the four flares, we observed continuous decay and cancellation of negative polarity flux within the atoll region. Accordingly, the apparent length of the HFT gradually reduced to a null-point-like configuration before the fourth flare. Prior to each flare, we observed localised brightening beneath the filaments which, together with flux cancellation, provided support for the tether-cutting model of solar eruption. The analysis of magnetic decay index revealed favourable conditions for the eruption, once the pre-activated flux ropes attained the critical heights for torus instability.

show abstract

On the Role of Repetitive Magnetic Reconnections in Evolution of Magnetic Flux Ropes in Solar Corona

Cited by 31 publications

References 47 publications

A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

A Comparative Study of the Eruptive and Non-eruptive Flares Produced by the Largest Active Region of Solar Cycle 24

The Inhomogeneity of Composition Along the Magnetic Cloud Axis

Successive occurrences of quasi-circular ribbon flares in a fan-spine-like configuration involving hyperbolic flux tube

Contact Info

Product

Resources

About